Commodore 64 peripherals
Encyclopedia
This article is about the various external peripherals of the Commodore 64
Commodore 64
The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...

 home computer
Home computer
Home computers were a class of microcomputers entering the market in 1977, and becoming increasingly common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user...

.

Tape drives

In the United States, the 1541 floppy disk drive was widespread. By contrast, in Europe the C64 was often used with cassette tape drives (Datasettes), which were much cheaper, but also much slower than floppy drives. The datasette functioned similarly to a 300 baud modem, converting audio analog sounds into digital format. It plugged into a proprietary cassette port on the Commodore 64's motherboard
Motherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...

. Standard blank audio cassettes could be used in this drive.

The datasette's speed was very slow (about 300 baud
Baud
In telecommunications and electronics, baud is synonymous to symbols per second or pulses per second. It is the unit of symbol rate, also known as baud rate or modulation rate; the number of distinct symbol changes made to the transmission medium per second in a digitally modulated signal or a...

). Loading a large program at normal speed could take up to thirty minutes in extreme cases. Many European software developers wrote their own fast tape loaders which replaced the internal KERNAL
KERNAL
The KERNAL is Commodore's name for the ROM-resident operating system core in its 8-bit home computers; from the original PET of 1977, followed by the extended but strongly related versions used in its successors; the VIC-20, Commodore 64, Plus/4, C16, and C128...

 code in the C64 and offered loading times more comparable to disk drive speeds. Novaload was perhaps the most popular tape loader used by British and American software developers. Early versions of Novaload had the ability to play music while a program loaded into memory, and was easily recognisable by its black border and digital bleeping sounds on loading. Other fastloaders included loading screen
Loading screen
A loading screen is a picture shown by a computer program, often a video game, while the program is loading or initializing.-Loading times:Loading screens that disguise the length of time that a program takes to load were common when computer games were loaded from cassette tape, a process which...

s, displaying computer artwork while the program loaded. More advanced fast loaders included minigame
Minigame
A minigame is a short video game often contained within another video game. A minigame is always smaller or more simplistic than the game in which it is contained. Minigames are sometimes also offered separately for free to promote the main game...

s for the user to play while the program loaded from cassette. One such minigame fastloader was Invade-a-Load
Invade-a-Load
Invade-a-Load was a loader routine used in software for Commodore 64 computer. It was used in commercial games that were stored on cassette tape and loaded using the Datassette...

.

In addition to low speeds, datasette users had to contend with interference from magnetic fields. Also, not too dissimilar to floppy drive users, the datasette's read head could become dirty or slip out of alignment. A small screwdriver could be used to align the tape heads, and a few companies capitalized by selling various commercial kits for datasette head-alignment tuning.

As the datasette lacked any random read-write access, users had to either wait while the tape ran its length, the computer printing messages like "SEARCHING FOR ALIEN BOXING... FOUND AFO... FOUND SPACE INVADERS... FOUND PAC-MAN... FOUND ALIEN BOXING... LOADING..." or else rely on a tape counter number to find the starting location of programs on cassette. Tape counter speeds varied over different datasette units making recorded counter numbers unreliable on different hardware.

An optional streaming tape drive
Tape drive
A tape drive is a data storage device that reads and performs digital recording, writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability.A tape drive provides...

, based upon the QIC-02 format, was available for the Xetec
Xetec
Xetec was founded in 1983 by Jon Flickinger, and was located in Salina, Kansas, United States. Before closing in 1995, the company produced many third-party products for the Commodore 64, Commodore 128, Amiga, Macintosh, Atari ST and PC computers....

 Lt. Kernal
Lt. Kernal
Lt. Kernal was the name given to a SCSI hard drive subsystem developed for the Commodore 64 and Commodore 128 home computers. The original design of both the technically complicated hardware interface and equally complex disk operating system came from Lloyd Sponenburgh and Roy Southwick of Fiscal...

 hard drive subsystem (see below). They were expensive and few were ever sold.

Floppy disk drives

Although usually not supplied with the machine, floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

 drives of the 5¼ inch (1541
Commodore 1541
The Commodore 1541 , made by Commodore International, was the best-known floppy disk drive for the Commodore 64 home computer. The 1541 was a single-sided 170 kilobyte drive for 5¼" disks...

, 1551
Commodore 1551
The Commodore 1551 was a floppy disk drive for the Commodore Plus/4 home computer. It resembled a charcoal-colored Commodore 1541 and plugged into the cartridge port, providing faster access than the C64/1541 combination...

, 1570
Commodore 1570
The Commodore 1570 was a 5¼" floppy disk drive for the Commodore 128 home/personal computer. It was a single-sided, 170KB version of the double-sided Commodore 1571, released as a stopgap measure when Commodore International was unable to provide large enough quantities of 1571s due to a shortage...

 and 1571
Commodore 1571
The Commodore 1571 was Commodore's high-end 5¼" floppy disk drive. With its double-sided drive mechanism, it had the ability to utilize double-sided, double-density floppy disks natively. This was in contrast to its predecessors, the 1541 and 1570, which could fully utilize such disks only if the...

) and, later, 3½ inch (1581
Commodore 1581
The Commodore 1581 is a 3½ inch double sided double density floppy disk drive made by Commodore Business Machines primarily for its C64 and C128 home/personal computers. The drive stores 800 kilobytes using an MFM encoding but format different from both MS-DOS , and the Amiga formats. With...

) variety were available from Commodore.

The 1541 was the standard floppy disk drive for the Commodore 64, with nearly all disk-based software programs released for the computer being distributed in the 1541 compatible floppy disk format. The 1541 was very slow in loading programs because of a poorly implemented serial bus
Serial communications
In telecommunication and computer science, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels...

, a legacy of the Commodore VIC-20
Commodore VIC-20
The VIC-20 is an 8-bit home computer which was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the PET...

.

The 1541 disk drive was notorious for not only its slow performance and large physical size compared to the C64 (the drive is almost as deep as the computer is wide), but also for its mechanical unreliability. Perhaps the most common failure involved the drive's read-write head mechanism. Many complex software copy-protection schemes used data stored on nonstandard tracks on floppies, forcing the drive, while reading the data, to seek to track zero, which caused the head drive mechanism to slam into a mechanical stop. This produced a loud, telltale knocking sound and, more seriously, would over time often move the head mechanism out of precise alignment, resulting in read errors and necessitating repairs. Some demos even exploited this to force the disk drive to play crude tunes (Bicycle Built For Two
Daisy Bell
"Daisy Bell" is a popular song with the well-known chorus "Daisy, Daisy/Give me your answer do/I'm half crazy/all for the love of you" as well as the line "...a bicycle built for two".-History:"Daisy Bell" was composed by Harry Dacre in 1892...

was one) by varying the knocking of the mechanism.

Also, as with the C64, 1541 drives tended to overheat due to a design that did not permit adequate cooling (potentially fixed by mounting a small fan to the case). Many of the 1541's design problems were eventually rectified in Commodore's 1541-II disk drive, which was 100 percent compatible with the older units. The power supply unit was not housed inside the drive case, hence the 1541-II size was significantly smaller and did not overheat.

In the following example, '*' designates the last program loaded, or the first program on the disk, '8' is the disk drive device number, and the '1' signifies that the file is to be loaded not to the standard memory address
Memory address
A digital computer's memory, more specifically main memory, consists of many memory locations, each having a memory address, a number, analogous to a street address, at which computer programs store and retrieve, machine code or data. Most application programs do not directly read and write to...

 for BASIC programs, but to the address where its program header tells it to go—the address it was saved from. This last '1' usually signifies a machine language program.

LOAD "*",8,1

It wasn't too long after the 1541's introduction that third-party developers demonstrated that performance could be improved with software that took over control of the serial bus signal lines and implemented a better transfer protocol between the computer and disk. In 1984 Epyx
Epyx
Epyx, Inc. was a video game developer and publisher in the late 1970s and throughout the 1980s. The company was founded as Automated Simulations by Jim Connelley and Jon Freeman, originally using Epyx as a brand name for action-oriented games before renaming the company to match in 1983...

 released its FastLoad
Epyx FastLoad
The Epyx FastLoad is a floppy disk fast loader cartridge made by American software company Epyx in 1984 for the Commodore 64 home computer. It was programmed by Epyx employee Scott Nelson, who later designed the Epyx Vorpal fastloading system for the company's games.Epyx FastLoad allowed programs...

cartridge for the C64 which replaced some of the 1541's slow routines with its own custom code, thus allowing users to load programs at a fraction of the time. Despite being incompatible with many programs' copy protection
Copy protection
Copy protection, also known as content protection, copy obstruction, copy prevention and copy restriction, refer to techniques used for preventing the reproduction of software, films, music, and other media, usually for copyright reasons.- Terminology :Media corporations have always used the term...

 schemes, the cartridge became so popular among grateful C64 owners (likely the most-widespread third-party enhancement for the C64 of all time) that many Commodore dealers sold the Epyx cartridge as a standard item when selling a new C64 with the 1541.

As a free alternative to FastLoad cartridges, numerous pure software turbo-loader programs were also created that were loaded to RAM each time after the computer was reset. The best of these turbo-loaders were able to accelerate the time required for loading a program from the floppy drive up to a very remarkable factor of 20x, demonstrating the default bus implementation's inadequacy. As turbo-loader programs were relatively small programs, it was common to place one on almost each floppy disk so that it could be quickly loaded to RAM after restart.

The 1541 floppy drive contained a MOS
MOS Technology
MOS Technology, Inc., also known as CSG , was a semiconductor design and fabrication company based in Norristown, Pennsylvania, in the United States. It is most famous for its 6502 microprocessor, and various designs for Commodore International's range of home computers.-History:MOS Technology, Inc...

 6502
MOS Technology 6502
The MOS Technology 6502 is an 8-bit microprocessor that was designed by Chuck Peddle and Bill Mensch for MOS Technology in 1975. When it was introduced, it was the least expensive full-featured microprocessor on the market by a considerable margin, costing less than one-sixth the price of...

 processor acting as the drive controller, along with a built-in disk operating system (DOS
Commodore DOS
Commodore DOS, aka CBM DOS, was the disk operating system used with Commodore's 8-bit computers. Unlike most other DOS systems before or since—which are booted from disk into the main computer's own RAM at startup, and executed there—CBM DOS was executed internally in the drive: the DOS...

) in ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...

 and a small amount of RAM
Ram
-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...

, the latter primarily used for buffer
Buffer (computer science)
In computer science, a buffer is a region of a physical memory storage used to temporarily hold data while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device or just before it is sent to an output device...

 space. Since this arrangement was, in effect, a specialized computer, it was possible to write custom controller routines and load them into the drive's RAM, thus making the drive work independently of the C64 machine. In fact, there were many software packages that took advantage of this; for example, certain back up software allowed users to make multiple disk copies directly between daisy-chained drives without a C64.

Several third party vendors sold an IEEE-488
IEEE-488
IEEE-488 is a short-range digital communications bus specification. It was created for use with automated test equipment in the late 1960s, and is still in use for that purpose. IEEE-488 was created as HP-IB , and is commonly called GPIB...

 general purpose interface bus adapter for the C64, which plugged into the machine's expansion port. Outside of BBS
Bulletin board system
A Bulletin Board System, or BBS, is a computer system running software that allows users to connect and log in to the system using a terminal program. Once logged in, a user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging...

 operators, few C64 owners took advantage of this arrangement and the accompanying IEEE devices that Commodore sold (such as the SFD-1001 1-megabyte
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

 5¼ inch floppy disk drive, and the peripherals originally made for the IEEE equipped PET
Commodore PET
The Commodore PET was a home/personal computer produced from 1977 by Commodore International...

 computers, such as the 4040 and 8050 drives and the 9060/9090 hard disk
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...

 drives).

As an alternative to the feeble performing 1541 or the relatively expensive IEEE bus adapter and associated peripheral
Peripheral
A peripheral is a device attached to a host computer, but not part of it, and is more or less dependent on the host. It expands the host's capabilities, but does not form part of the core computer architecture....

s, a number of third-party serial-bus drives such as the MSD Super Disk
MSD Super Disk
The MSD Super Disk was a series of floppy disk drives produced by Micro Systems Development for use with Commodore 8-bit home computers. Two different versions of the MSD Super Disk were available: the single-drive SD-1 and the dual-drive SD-2....

 and Indus GT
Indus GT
The Indus GT was a floppy disk drive made by Indus Systems of California, USA during the early 1980s for Commodore, Apple II series and Atari home computer platforms of the day. It came in a black casing with a smoke plexiglas cover over the drive mechanism. Behind the cover was an 8 segment LED...

 appeared that often offered better reliability, higher performance, quieter operation, or simply a lower price than the 1541, although often at the expense of software compatibility due to the difficulty of reverse engineering
Reverse engineering
Reverse engineering is the process of discovering the technological principles of a device, object, or system through analysis of its structure, function, and operation...

 the DOS built into the 1541's hardware (Commodore's IEEE-based drives faced the same issue due to the dependence of the DOS on features of the Commodore serial bus).

Like the IEEE-488
IEEE-488
IEEE-488 is a short-range digital communications bus specification. It was created for use with automated test equipment in the late 1960s, and is still in use for that purpose. IEEE-488 was created as HP-IB , and is commonly called GPIB...

 interface, the serial bus offered the ability to daisy chain
Daisy chain
Daisy chain may refer to a daisy garland created from daisy flowers, the original meaning and the one from which the following derive by analogy:*Daisy chain *Daisy chain *Daisy chain...

 hardware together — that is, one device (disk drive or printer) would be connected to the Commodore 64 and the others would be connected to each other in sequence. This led to Commodore producing (via a third party) the Commodore 4015, or VIC-switch. This device (now rarely seen) allowed up to 8 Commodore 64s to be connected to the device along with a string of peripherals, allowing each computer to share the connected hardware.

It was also possible, without requiring a VIC-switch, to connect two Commodore 64s to one 1541 floppy disk drive to simulate an elementary network
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....

, allowing the two computers to share data on a single disk (if the two computers made simultaneous requests, the 1541 admirably handled one whilst returning an error to the other, which surprised many people who expected the 1541's less-than-stellar drive controller to crash
Crash (computing)
A crash in computing is a condition where a computer or a program, either an application or part of the operating system, ceases to function properly, often exiting after encountering errors. Often the offending program may appear to freeze or hang until a crash reporting service documents...

 or hang). This functionality also worked with a mixed combination of PET
Commodore PET
The Commodore PET was a home/personal computer produced from 1977 by Commodore International...

, VIC-20
Commodore VIC-20
The VIC-20 is an 8-bit home computer which was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the PET...

, and other selected Commodore 8-bit
8-bit
The first widely adopted 8-bit microprocessor was the Intel 8080, being used in many hobbyist computers of the late 1970s and early 1980s, often running the CP/M operating system. The Zilog Z80 and the Motorola 6800 were also used in similar computers...

 computers.

In the mid-1980s, a 2.8-inch floppy disk drive, the Triton Disk Drive
Triton disk drive
The Triton Quick Disk Drive is a product that allows 2.8-inch floppy disks to be read on the Commodore 64, Spectrum, MSX, Aquarius and Dragon 64 home computers. The product was released for sale in the mid-1980s....

 and Controller, was introduced by Radofin Electronics, Ltd. It was compatible with the Commodore 64 as well as other popular home computers of the time, thanks to an operating system stored on an EPROM on an external controller. It offered a capacity of 144/100 kilotbytes non-formatted/formatted, and data transfer rates of up to 100 kilobytes per second. Up to 20 files could be kept on each side of the double-sided floppy disks.

Later in the 1990s, Creative Micro Designs
Creative Micro Designs
Creative Micro Designs is a computer technologies company which today sells PCs and related equipment, but which started out in 1987 selling self-designed firmware updates and hardware for the Commodore 64 and C128 8-bit home/personal computers....

 produced several powerful floppy disk drives for the Commodore 64. These included the FD-Series
CMD FD series
The CMD FD series was Creative Micro Designs 's range of third-party floppy disk drives for the Commodore 8-bit line of home computers. Using 3½" floppy disks, they provided a significantly larger storage capacity than Commodore-produced drives; the FD-2000 offered 1600KB of storage using standard...

 serial bus compatible 3.5" floppy drives (FD-2000, FD-4000), which were capable of emulating Commodore's 1581
Commodore 1581
The Commodore 1581 is a 3½ inch double sided double density floppy disk drive made by Commodore Business Machines primarily for its C64 and C128 home/personal computers. The drive stores 800 kilobytes using an MFM encoding but format different from both MS-DOS , and the Amiga formats. With...

 3.5" drive as well as implementing a native mode
Native mode
The term native mode or native code is used in computing in two related senses.*to describe something running on a computer natively or in native mode meaning that it is running without any external support as contrasted to running in emulation....

 partitioning which allowed typical 3.5"HD floppy disks to hold 1.6 MB of data - more than MS-DOS's 1.4 MB format. The FD-4000 drive had the advantage of being able to read hard-to-find enhanced floppy disks and could be formatted to hold 3.2 MB of data. In addition, the FD series drives could partition floppy disks to emulate the 1541, 1571 and 1581 disk format (although unfortunately, not the emulated drive firmware), and a real time clock module could be mounted inside the drive to time-stamp files. Commercially, very little software was ever released on either 1581 disk format or CMD's native format. However, enthusiasts could use this drive to transfer data between typical PC MS-DOS and the Commodore with special software.

There was one other 3.5" floppy drive available for the Commodore 64. The "TIB 001" was 3.5" floppy drive which connected to the Commodore 64 via the expansion port, meaning that these drives were very fast. The floppy disks themselves relied on an MS-DOS disk format, and being based on cartridge, allowed the Commodore 64 to boot from them automatically at start-up. These devices appeared from a company in the United Kingdom, but unfortunately did not become widespread due to non-existant third-party support. In an article in Zzap!64 of November 1991, several software houses interviewed believed that the device came to the market too late to be worthy of supporting.

Hard drives

Late in 1984, Fiscal Information Inc., of Florida, demonstrated the Lt. Kernal
Lt. Kernal
Lt. Kernal was the name given to a SCSI hard drive subsystem developed for the Commodore 64 and Commodore 128 home computers. The original design of both the technically complicated hardware interface and equally complex disk operating system came from Lloyd Sponenburgh and Roy Southwick of Fiscal...

 hard drive subsystem for the C64
Commodore 64
The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...

. The Lt. Kernal was revolutionary in that it mated a 10 megabyte
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

, Seagate
Seagate Technology
Seagate Technology is one of the world's largest manufacturers of hard disk drives. Incorporated in 1978 as Shugart Technology, Seagate is currently incorporated in Dublin, Ireland and has its principal executive offices in Scotts Valley, California, United States.-1970s:On November 1, 1979...

 ST-412 hard drive to an OMTI SASI intelligent controller, creating a high speed bus interface to the C64's expansion port. Connection of the SASI bus to the C64 was accomplished with a custom designed host adapter
Host adapter
In computer hardware, a host controller, host adapter, or host bus adapter connects a host system to other network and storage devices...

. The Lt. Kernal shipped with a sophisticated minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...

-like disk operation system (DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...

) that, among other things, allowed execution of a program by simply typing its name and pressing the Return key. The DOS also included a keyed random access feature that made it possible for a skilled programmer to implement ISAM
ISAM
ISAM stands for Indexed Sequential Access Method, a method for indexing data for fast retrieval. ISAM was originally developed by IBM for mainframe computers...

 style databases.

By 1987, the manufacturing and distribution of the Lt. Kernal had been turned over to Xetec
Xetec
Xetec was founded in 1983 by Jon Flickinger, and was located in Salina, Kansas, United States. Before closing in 1995, the company produced many third-party products for the Commodore 64, Commodore 128, Amiga, Macintosh, Atari ST and PC computers....

, Inc., who also introduced C128
Commodore 128
The Commodore 128 home/personal computer was the last 8-bit machine commercially released by Commodore Business Machines...

 compatibility (including support for CP/M
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...

). Standard drive size had been increased to 20 MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

, with 40 MB available as an option, and the system bus was now the industry-standard small computer system interface
SCSI
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...

, better known as SCSI
SCSI
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...

 (the direct descendant of SASI).

The Lt. Kernal
Lt. Kernal
Lt. Kernal was the name given to a SCSI hard drive subsystem developed for the Commodore 64 and Commodore 128 home computers. The original design of both the technically complicated hardware interface and equally complex disk operating system came from Lloyd Sponenburgh and Roy Southwick of Fiscal...

 was the most technically advanced hard drive subsystem ever offered for Commodore 8 bit computers and was capable of a data transfer rate of over 38 KB
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...

 per second (65 KB per second in C128 fast mode). An optional multiplexer allowed one Lt. Kernal drive to be shared by as many as sixteen C64s or C128s (in any combination), using a round-robin scheduling algorithm
Round-robin scheduling
Round-robin is one of the simplest scheduling algorithms for processes in an operating system. As the term is generally used, time slices are assigned to each process in equal portions and in circular order, handling all processes without priority . Round-robin scheduling is simple, easy to...

 that took advantage of the SCSI bus protocol's ability to handle multiple initiators
SCSI initiator
In computer data storage, a SCSI initiator is the endpoint that initiates a SCSI session, that is, sends a SCSI command. The initiator usually does not provide any Logical Unit Numbers ....

 and targets. Thus the Lt. Kernal could be conveniently used in a multi-computer setup, something that was not possible with other C64-compatible hard drives.

Production of the Lt. Kernal ceased in 1991. Fortunately, most of the components used in the original design were industry standard parts, making it possible to make limited repairs to the units. In 2010, a modern re-creation of the Lt. Kernal was produced by MyTec. It was called the Rear Admiral and used an upgraded DOS called RA-DOS. The Rear Admiral parts could be used to upgrade the older Lt. Kernal, e.g. chips from the Rear Admiral host adapter could be used to upgrade the chips in the Lt. Kernal host adapter; or if the Lt. Kernal is missing its host adapter, the Rear Admiral host adapter could be used in its place.

Also available for the Commodore 64
Commodore 64
The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...

 was the Creative Micro Designs CMD HD-Series. Much like the Commodore 1541 floppy drive, the CMD HD could connect to the Commodore 64's serial bus, and could operate independently of the computer with the help of its on-board hardware. A CMD HD series drive included its own SCSI
SCSI
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...

 controller to operate its hard drive mechanism, in addition to hosting a battery powered real-time clock module for the time-stamping of files. The stock operating speeds of the CMD HD-Series units were not very much faster than the stock speeds of a 1541 floppy drive, but thankfully the units were fully JiffyDOS compatible. Faster parallel transfers were possible with the addition of another CMD product, the CMD RAMLink
CMD RAMLink
The RAMLink was one of several RAM expansion products made by Creative Micro Designs for Commodore's C64/128 home computers. The RAMLink was intended as a third-party alternative, successor and optionally companion to Commodore's own 17xx-series REU RAM expansion cartridges.Unlike the REU, the...

 and a special parallel transfer cable. With this arrangement, the performance of the system doubled that of the Lt. Kernal. One advantage the CMD products had was software compatibility, especially with GEOS, that prior solutions lacked. Unfortunately, CMD missed opportunities to develop any features for the drive's auxiliary port (such as a printer spooler feature promised in the CMD HD user manual). Support for external SCSI devices (such as CD-ROM
CD-ROM
A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....

 and Zip drive
Zip drive
The Zip drive is a medium-capacity removable disk storage system that was introduced by Iomega in late 1994. Originally, Zip disks launched with capacities of 100 MB, but later versions increased this to first 250 MB and then 750 MB....

s) was also noticeably missing. SCSI devices could be connected and chained to the external SCSI port, but could not be used from the HD without workarounds or special software.

User operation of these hard drive subsystems was similar to that of Commodore's floppy drives, with the inclusion of special DOS features to make best use of the drive's capabilities and to effectively manage the vast increase in storage capacity (up to a maximum of 4GB). An unavoidable problem was that total 1541 compatibility could not be achieved, which often prevented the use of copy-protected software, software fastloaders, or any software whose operation depended on exact 1541 emulation.

The enthusiast-built "IDE64
IDE64
The IDE64 interface cartridge is an expansion port device for connecting ATA devices to the C64 or C128 computers.-Hardware:There were several somewhat different versions of this cartridge over the years. The interface was designed by Tomas Pribyl and Jan Vorlicek in 1994...

 interface" was designed late in the 1990s, attaching itself in the Commodore 64's expansion port, and allowing users to attach common IDE hard drives, CD-ROM
CD-ROM
A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....

 and DVD drives, ZiP and LS-120 floppy drives to their Commodore 64s. Later revisions of the interface board provided an extra compact flash socket. The IDE interface's performance is comparable to the RAMLink
CMD RAMLink
The RAMLink was one of several RAM expansion products made by Creative Micro Designs for Commodore's C64/128 home computers. The RAMLink was intended as a third-party alternative, successor and optionally companion to Commodore's own 17xx-series REU RAM expansion cartridges.Unlike the REU, the...

 in speed, but lacks the intelligence of SCSI. Its main advantage lies in being able to use inexpensive commodity hard drives instead of the more costly SCSI units. 1541 compatibility is not as good as commercially developed hard drive subsystems, but continues to improve with time.

Input/Output

Printers

A series of dot-matrix printers were sold by Commodore, including the MPS 801 and the MPS 803, although many other third-party printers like the Okimate 10
Okimate 10
The Okimate 10 by Oki Electric Industry was a low-cost 1980s color printer with interface "plug 'n print" modules for Commodore, Atari, IBM PC, and Apple Inc. home computers....

 and Okidata 120 were popular too - some having more advanced printing features than any of Commodore's models. Most Commodore-branded printers were rebranded C. Itoh or Epson models with Commodore serial interface.

Commodore also produced the DPS-1101 daisy wheel printer
Daisy wheel printer
Daisy wheel printers use an impact printing technology invented in 1969 by David S. Lee at Diablo Data Systems. It uses interchangeable pre-formed type elements, each with typically 96 glyphs, to generate high-quality output comparable to premium typewriters such as the IBM Selectric, but two to...

, which produced letter quality print similar to a typewriter
Typewriter
A typewriter is a mechanical or electromechanical device with keys that, when pressed, cause characters to be printed on a medium, usually paper. Typically one character is printed per keypress, and the machine prints the characters by making ink impressions of type elements similar to the pieces...

, and which typically cost more than the computer and floppy disk drive together. The MPS-1000 dot matrix printer was introduced along with the C-128. Commodore 1526 is a rebranded MPS 802.
A mini plotter device, the Commodore 1520, could plot graphics and print text in four colors by using tiny ballpoint pen
Ballpoint pen
A ballpoint pen is a writing instrument with an internal ink reservoir and a sphere for a point. The internal chamber is filled with a viscous ink that is dispensed at its tip during use by the rolling action of a small sphere...

s.

Commodore-specific printers were attached to the C64 via the serial port and were capable of being daisy chained to the system with other serial port devices such as floppy drives. By convention, printers were addressed as device #4-5 on the Commodore serial bus.

Since there were severe shortcomings of early Commodore printers, CARDCO released the Card Print A (C/?A) printer interface that emulated Commodore printers by converting the Commodore-style IEEE-488
IEEE-488
IEEE-488 is a short-range digital communications bus specification. It was created for use with automated test equipment in the late 1960s, and is still in use for that purpose. IEEE-488 was created as HP-IB , and is commonly called GPIB...

 serial interface to a Centronics printer port to allow numerous 3rd-party printers to be connected to a Commodore 64, such as Epson, Okidata, C. Itoh. A second model, a version that supported printer graphics was released called the Card Print +G (C/?+G), supported printing Commodore graphic characters using ESC/P
ESC/P
ESC/P is a command language developed by Epson to control computer printers. It was mainly used in dot matrix printers and some inkjet printers. During the era of dot matrix printers, it was also used by other manufacturers , sometimes in modified form...

 escape codes. CARDCO released additional enhancements, including a model with RS-232 output, and shipped a total over 2 million printer interfaces. Xetec
Xetec
Xetec was founded in 1983 by Jon Flickinger, and was located in Salina, Kansas, United States. Before closing in 1995, the company produced many third-party products for the Commodore 64, Commodore 128, Amiga, Macintosh, Atari ST and PC computers....

 also released a series of printer interfaces. Later, CMD
Creative Micro Designs
Creative Micro Designs is a computer technologies company which today sells PCs and related equipment, but which started out in 1987 selling self-designed firmware updates and hardware for the Commodore 64 and C128 8-bit home/personal computers....

 created the GeoCable which allowed PS2-type ink-jet and laser printers to work under GEOS with a special device driver
Device driver
In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....

.

Input devices

Commodore produced joystick
Joystick
A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticks, also known as 'control columns', are the principal control in the cockpit of many civilian and military aircraft, either as a center stick or...

 controllers for the Commodore 64, largely compatible with Atari
Atari
Atari is a corporate and brand name owned by several entities since its inception in 1972. It is currently owned by Atari Interactive, a wholly owned subsidiary of the French publisher Atari, SA . The original Atari, Inc. was founded in 1972 by Nolan Bushnell and Ted Dabney. It was a pioneer in...

 joysticks, as well as paddles
Paddle (game controller)
A paddle is a game controller with a round wheel and one or more fire buttons, where the wheel is typically used to control movement of the player object along one axis of the video screen...

 (which were not Atari compatible). Commodore's paddles were originally intended for the VIC-20, and few C64 games could take advantage of them. Commodore's joysticks were often derided because they were not particularly robust, especially for extreme gameplay. Many gaming enthusiasts preferred third-party joysticks, while some enthusiasts even built their own joysticks and controllers for the Commodore 64, or modified controllers from other systems to work on it. While the Commodore 64 only had two joystick ports for use, a few different kinds of joystick adapters
Commodore 64 joystick adapters
Commodore 64 joystick adapters are hardware peripherals that extend the number of joystick ports on the Commodore 64 computer. The additional joysticks can be used on games with dedicated support for the specific adapter....

 were constructed by enthusiasts, which allowed up to four or eight joysticks to be used on the Commodore 64, with appropriate programming. Only about 20 games (by 2011) can take advantage of these however.

Commodore had two models of computer mouse, namely the 1350 and the 1351
Commodore 1351
The Mouse 1351 is a mouse made by Commodore in 1986, which can directly be plugged into the 9-pin control port of a C64/128/D/DCR.- Description :...

. These were used with GEOS
GEOS (8-bit operating system)
GEOS is an operating system from Berkeley Softworks . Originally designed for the Commodore 64 and released in 1986, it provided a graphical user interface for this popular 8-bit computer.GEOS closely resembled early versions of Mac OS and included a graphical word processor and paint program...

 as well as software such as Jane
Jane (software)
Jane 128 was a GUI-based integrated software package for the Commodore 128 personal computer developed by Arktronics and released by Commodore International in 1985...

 and Magic Desk. The earlier 1350 was only capable of emulating a digital joystick, by sending rapid 8 directional signals as it was moved, and thus was not very useful. The later 1351 used a more traditional proportional mode, sending signals to the computer that indicate amount and direction of movement. The 1351 also supported a mode identical to that of the 1350. CMD's SmartMouse was compatible with 1351-aware and also included a third button and a built in real-time clock module as well. The NEOS mouse also existed, but it was not compatible with 1351-aware software as it was simply a joystick emulator.

Sveral Companies produced Lightpens with its own drawing software for the Computer, e.g. the Inkwell light pen
Light pen
A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a computer's CRT TV set or monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy...

 which was compatible with GEOS.

The Koala Pad, an early form of touchpad
Touchpad
A touchpad is a pointing device featuring a tactile sensor, a specialized surface that can translate the motion and position of a user's fingers to a relative position on screen. Touch pads are a common feature of laptop computers, and they are also used as a substitute for a mouse where desk...

 was also available, came with its own paint software, and was compatible with GEOS as well. Suncom's Animation Station was another graphics tablet
Graphics tablet
A graphics tablet is a computer input device that enables a user to hand-draw images and graphics, similar to the way a person draws images with a pencil and paper. These tablets may also be used to capture data or handwritten signatures...

 for the C64.

Modems

As Commodore offered a number of inexpensive modem
Modem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...

s for the C64, such as the 1650, 1660, 1670, the machine also helped popularize the use of modems for telecommunications. The 1650 and 1660 were 300 Baud, and the 1670 was 1200 baud. The 1650 could only dial Pulse. The 1660 had no sound chip of its own to generate Touch Tones, so a cable from the monitor /audio out was required to be connected to the 1660 so it could use the C64 sound chip to generate Touch Tones. The 1670 used a modified set of Hayes Commands.

This modem is required for Medical Manager for EDI operations.

The Commodore 1650 shipped with a rudimentary piece of terminal software called Common Sense. It provided basic Xmodem
XMODEM
XMODEM is a simple file transfer protocol developed as a quick hack by Ward Christensen for use in his 1977 MODEM.ASM terminal program. XMODEM became extremely popular in the early bulletin board system market, largely because it was so simple to implement...

 functionality and contained a 700 line scrollback feature.

In the United States, Quantum Computer Services (later America Online) offered an online service called Quantum Link
Quantum Link
Quantum Link was a U.S. and Canadian online service for Commodore 64 and 128 personal computers that operated from November 5, 1985 to November 1, 1995. It was operated by Quantum Computer Services of Vienna, Virginia. In October 1991 they changed the name to America Online, which continues to...

 for the C64 that featured chat, downloads, and online games. In the UK, Compunet
Compunet
Compunet was a United Kingdom based interactive service provider, catering primarily for the Commodore 64 but later for the Commodore Amiga and Atari ST...

 was a very popular online service for C64 users (requiring special Compunet modems) from 1984 to the early 1990s. In Australia, Telecom (now Telstra
Telstra
Telstra Corporation Limited is an Australian telecommunications and media company, building and operating telecommunications networks and marketing voice, mobile, internet access and pay television products and services....

) ran an online service called Viatel and sold modems for the C64 for use with the service. In Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 the very restrictive rules of the state-owned telephone system prevented widespread use of modems, prompting the use of inferior acoustic coupler
Acoustic coupler
In telecommunications, the term acoustic coupler has the following meanings:# An interface device for coupling electrical signals by acoustical means—usually into and out of a telephone instrument....

s instead.

RS-232 port

Like the VIC-20, the C64 lacked a real UART
Universal asynchronous receiver/transmitter
A universal asynchronous receiver/transmitter, abbreviated UART , is a type of "asynchronous receiver/transmitter", a piece of computer hardware that translates data between parallel and serial forms. UARTs are commonly used in conjunction with communication standards such as EIA RS-232, RS-422 or...

 chip such as the 6551
MOS Technology 6551
The 6551 Asynchronous Communications Interface Adapter was an integrated circuit made by MOS Technology. It served as a companion UART chip for the widely popular 6502 microprocessor. Intended to implement RS-232, its specifications called for a maximum speed of 19,200 bits per second...

 and used software emulation. This limited the maximum speed to an error-prone 2400 bit/s. Third-party cartridges with UART chips offered better performance.

Later in the Commodore 64's life, CMD
Creative Micro Designs
Creative Micro Designs is a computer technologies company which today sells PCs and related equipment, but which started out in 1987 selling self-designed firmware updates and hardware for the Commodore 64 and C128 8-bit home/personal computers....

 developed two serial communications cartridges for Commodore Computers, the "Swiftlink" and the "Turbo 232". The latter was capable of handling a 56k Hayes modem
Modem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...

 at full speed, enabling reasonable dial-up internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

 access speeds.

The Retro-Replay expansion cartridge enabled the addition of the Silver Surfer add-on serial board, which also enabled 56k modem connections, and the RR-Net add-on serial board, which allows for broadband internet access, as well as LAN
Local area network
A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...

.

Also, on November 5, 2005 Quantum Link Reloaded was launched enabling C64 enthusiasts to experience all the features of the original Quantum Link
Quantum Link
Quantum Link was a U.S. and Canadian online service for Commodore 64 and 128 personal computers that operated from November 5, 1985 to November 1, 1995. It was operated by Quantum Computer Services of Vienna, Virginia. In October 1991 they changed the name to America Online, which continues to...

 service in present-day with some enhancements for free. The server is located at 66.135.39.36 on port 5190.

Other peripherals

The Commodore 1701 and 1702 were 13-inch (33 cm) color monitors for the C64 which accepted as input either composite video or separate chrominance
Chrominance
Chrominance is the signal used in video systems to convey the color information of the picture, separately from the accompanying luma signal . Chrominance is usually represented as two color-difference components: U = B' − Y' and V = R' − Y'...

 and luminance
Luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square...

 signals, similar to the S-Video
S-Video
Separate Video, more commonly known as S-Video and Y/C, is often referred to by JVC as both an S-VHS connector and as Super Video. It is an analog video transmission scheme, in which video information is encoded on two channels: luma and chroma...

 standard, for superior performance with the C64 (or other devices capable of outputting a separated signal). Other monitors available included the 1802 and 1902. Introduced in 1986, the 1802 featured separate chroma and luma signals, as well as a composite green screen mode suitable for the C-128's 80 column mode. The 1902 had a true RGBI
RGBI
RGBI could refer to:* Rio Grande Bible Institute* RGBI interface — Red, Green, Blue, Intensity, as in an RGBI cathode ray tube monitor interface; cf. Color Graphics Adapter...

 80-column mode compatible with the IBM PC
IBM PC
The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...

s.

Early in the Commodore 64's life, Commodore released several niche hardware enhancements for sound manipulation. These included the "Sound Expander", "Sound Sampler", "Music Maker" overlay, and External music keyboard. The Sound Expander and Sound Sampler were both expansion cartridges, but had limited use. The Sound Sampler in particular could only record close to two seconds of audio, rendering it largely useless. The Music Maker was a plastic overlay for the Commodore 64 "breadbox" keyboard, which included plastic piano keys corresponding to keys on the keyboard. The External keyboard was an add-on which plugged into the Sound Expander. These hardware devices did not sell well, perhaps due to their cost, lack of adequate software, marketing as home consumer devices, and an end result that turned many serious musicians off.

CMD
Creative Micro Designs
Creative Micro Designs is a computer technologies company which today sells PCs and related equipment, but which started out in 1987 selling self-designed firmware updates and hardware for the Commodore 64 and C128 8-bit home/personal computers....

 produced a SID
MOS Technology SID
The MOS Technology 6581/8580 SID is the built-in Programmable Sound Generator chip of Commodore's CBM-II, Commodore 64, Commodore 128 and Commodore MAX Machine home computers...

 symphony cartridge later in the Commodore's life. This cartridge gave the Commodore another SID chip for use to play stereo SID music. This saved Commodore 64 users from needing to modify their computer motherboards to enable it with dual SID chips.

Creative Micro Designs
Creative Micro Designs
Creative Micro Designs is a computer technologies company which today sells PCs and related equipment, but which started out in 1987 selling self-designed firmware updates and hardware for the Commodore 64 and C128 8-bit home/personal computers....

 (CMD) was the longest-running third-party hardware vendor for the Commodore 64 and Commodore 128
Commodore 128
The Commodore 128 home/personal computer was the last 8-bit machine commercially released by Commodore Business Machines...

, hailed by some enthusiasts as being better at supporting the Commodore 64 than Commodore themselves. Their first commercial product for the C64 was a KERNAL
KERNAL
The KERNAL is Commodore's name for the ROM-resident operating system core in its 8-bit home computers; from the original PET of 1977, followed by the extended but strongly related versions used in its successors; the VIC-20, Commodore 64, Plus/4, C16, and C128...

 based fast loader and utility chip called JiffyDOS. It was not the first KERNAL-based enhancement for the C64 (SpeedDOS and DolphinDOS also existed), but was perhaps the best implemented. The benefits of a KERNAL upgrade meant that the cartridge port was free for use (which would have normally been taken up by an Epyx
Epyx
Epyx, Inc. was a video game developer and publisher in the late 1970s and throughout the 1980s. The company was founded as Automated Simulations by Jim Connelley and Jon Freeman, originally using Epyx as a brand name for action-oriented games before renaming the company to match in 1983...

 FastLoad
Epyx FastLoad
The Epyx FastLoad is a floppy disk fast loader cartridge made by American software company Epyx in 1984 for the Commodore 64 home computer. It was programmed by Epyx employee Scott Nelson, who later designed the Epyx Vorpal fastloading system for the company's games.Epyx FastLoad allowed programs...

 cartridge or an Action Replay
Action Replay
Action Replay is the brand name of a series of video game cheating devices created by Datel. As of 2010, Action Replays are currently available for some of the current major gaming platforms which include the Nintendo DS, Nintendo DSi, PlayStation 2, and the PlayStation Portable, and many older...

), however the downside meant that one had to manually remove computer chips from the C64's motherboard
Motherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...

 and associated floppy drives to install it. Aside from the usual 1541 fast load routines, JiffyDOS contained an easy to use DOS
Disk operating system
Disk Operating System and disk operating system , most often abbreviated as DOS, refers to an operating system software used in most computers that provides the abstraction and management of secondary storage devices and the information on them...

 and a few other useful utilities.

RAM expansions

Over the years, a number of RAM expansion cartridges were developed for the Commodore 64 and 128. Commodore officially produced several models of RAM
Ram
-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...

 expansion cartridges, referred to collectively as the 17xx-series Commodore REU
Commodore REU
Commodore's RAM Expansion Unit range of external RAM add-ons for their Commodore 64/128 home computers was announced at the same time as the C128. The REUs came in three models, initially the 1700 and 1750 , and later the 1764...

s. While these devices came in 128, 256, or 512 KB
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...

 sizes, third-party modifications were quickly developed that could extend these devices to 2 MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

, although some such modifications could be unstable. Some companies also offered services to professionally upgrade these devices.

Typically, most Commodore 64 users did not require a RAM expansion, due to a number of problems associated with them. One such problem with the various Commodore-made 17xx-series devices was their power draw from the Commodore 64 computer. Some models required the Commodore 64 to be powered by a heavy-duty power supply, and these power supplies were typically not supplied with the Commodore 64. Eventually, a number of third-party clones of Commodore's RAM expansions were developed, some of which were designed in such a way as to eliminate the need for a heavy-duty power supply.

Aside from power-supply problems, the other main downfall of the RAM expansions were their limited usability due to their technical implementation. The RAM in the expansion cartridges was only accessible via a handful of hardware registers, rather than being CPU-addressable memory. This meant that users could not access this RAM without complicated programming techniques. Furthermore, simply adding the RAM expansion did not provide any kind of on-board RAM disk
RAM disk
A RAM disk or RAM drive is a block of RAM that a computer's software is treating as if the memory were a disk drive...

 functionality (though a utility disk was supplied with some REUs, which provided a loadable RAM disk driver).

One popular exception to the disuse of the REU was GEOS
GEOS (8-bit operating system)
GEOS is an operating system from Berkeley Softworks . Originally designed for the Commodore 64 and released in 1986, it provided a graphical user interface for this popular 8-bit computer.GEOS closely resembled early versions of Mac OS and included a graphical word processor and paint program...

. As GEOS made heavy use of a primitive, software-controlled form of swap space, it tended to be slow when used exclusively with floppy disks or hard drives. With the addition of an REU, along with a small software driver, GEOS would use the expanded memory in place of its usual swap space, increasing GEOS' operating speed.

Berkeley Softworks later developed its own 512 KB RAM expansion cartridge - the GeoRAM. This device was purposely designed for use with GEOS, although some REU-aware programs were later adapted to be able to use it. Some time later, the GeoRAM was cloned by another company to form the BBGRAM device (which also sported a battery backup unit).

PPI devised their own externally-powered 1 or 2 MB RAM expansion, marketed as the PPI/CMD RAMDrive, which was explicitly designed to be used as a RAM disk. Its primary feature was that the external power supply kept the formatting and contents of the RAM safe and valid while the computer was turned off, in addition to powering the device in any case. A driver was provided on the included utilities disk to allow GEOS to use the RAMdrive as a regular 'disk' drive.

CMD later followed up with the RAMLink
CMD RAMLink
The RAMLink was one of several RAM expansion products made by Creative Micro Designs for Commodore's C64/128 home computers. The RAMLink was intended as a third-party alternative, successor and optionally companion to Commodore's own 17xx-series REU RAM expansion cartridges.Unlike the REU, the...

. This device operated similar to the RAMDrive, but could address up to 16 MB of RAM in the form of a 17xx-series REU, GeoRAM, and/or an internal memory card, which also provided a battery-backed realtime clock for file time/date stamping of files saved to it. It also features a battery backup, thus preserving the RAM's contents. Drivers were provided with the RAMLink to allow GEOS to use its memory as either a replacement for swap space, or as a regular 'disk' drive.

CMD's Super CPU Accelerator came after this, and could house up to 16 MB of direct, CPU-addressable RAM. Unfortunately, there was no on-board or disk-based RAM disk functionality offered, nor could any existing software make use of the directly-addressable nature of the RAM. The exception is that drivers were included with the unit to explicitly allow GEOS to use that RAM as a replacement for swap space, or as a regular 'disk' drive, as well as to make use of the acceleration offered by the unit.

Freezer, Reset, and Utility cartridges

Probably the most well-known hacker and development tools for the Commodore 64 included "Reset" and "Freezer" cartridges. As the C64 had no built-in soft reset switch, reset cartridges were popular for entering game "POKEs
PEEK and POKE
In computing, PEEK is a BASIC programming language extension used for reading the contents of a memory cell at a specified address. The corresponding command to set the contents of a memory cell is POKE.-Statement syntax:...

" (codes which changed parts of a game's code in order to cheat) from popular Commodore computer magazines. Freezer cartridges had the capability to not only manually reset the machine, but also to dump the contents of the computer's memory and send the output to disk or tape. In addition, these cartridges had tools for editing game sprites, machine language monitors, floppy fast loaders, and other development tools. Freezer cartridges were not without controversy however. Despite containing many powerful tools for the programmer, they were also accused of aiding software pirates to defeat software copy protections. Perhaps the best known freezer cartridges were the Datel
Datel
Datel is a UK-based electronics and game console peripherals manufacturer. The company is best known for producing a wide range of hardware and peripherals for home computers in the 1980s, for example replacement keyboards for the ZX Spectrum, the PlusD disk interface and the Action Replay series...

 "Action Replay
Action Replay
Action Replay is the brand name of a series of video game cheating devices created by Datel. As of 2010, Action Replays are currently available for some of the current major gaming platforms which include the Nintendo DS, Nintendo DSi, PlayStation 2, and the PlayStation Portable, and many older...

", Evesham Micros Freeze Frame MK III B, Trilogic "Expert", "The Final Cartridge III
The Final Cartridge III
The Final Cartridge III was a popular extension cartridge which was created for the Commodore 64 and Commodore 128, produced by Riska B.V. Home & Personal Computers...

", and Super Snapshot cartridges.

The Lt. Kernal
Lt. Kernal
Lt. Kernal was the name given to a SCSI hard drive subsystem developed for the Commodore 64 and Commodore 128 home computers. The original design of both the technically complicated hardware interface and equally complex disk operating system came from Lloyd Sponenburgh and Roy Southwick of Fiscal...

 hard drive subsystem included a push button on the host adapter
Host adapter
In computer hardware, a host controller, host adapter, or host bus adapter connects a host system to other network and storage devices...

 called ICQUB , which could be used to halt a running program and capture a RAM
Ram
-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...

 image to disk. This would work with most copy-protected software that did not do disk overlays
Overlay (programming)
In a general computing sense, overlaying means "replacement of a block of stored instructions or data with another" Overlaying is a programming method that allows programs to be larger than the computer's main memory...

 and/or bypass the KERNAL
KERNAL
The KERNAL is Commodore's name for the ROM-resident operating system core in its 8-bit home computers; from the original PET of 1977, followed by the extended but strongly related versions used in its successors; the VIC-20, Commodore 64, Plus/4, C16, and C128...

 ROM jump table. The RAM image was runnable only on the Lt. Kernal system on which it was captured, thus preventing the process from being used to pirate software.

Other Music and Synthesizer utilities

As the Commodore 64 featured a digitally controlled semi-analogue synthesizer as its sound processor, it wasn't surprising to discover an abundance of software and hardware designed to expand upon its capabilities.

Various assemblers, notators, sequencers, MIDI editing and mixer automation software were created which allowed users and programmers to create or record musical pieces of impressive technical complexity. Some software of note has included the Kawasaki Synthesizer range, Music System notation and MIDI suite, the MIDI-compatible Instant Music 'idiot-proof' sequential composer, and the Steinberg Pro-16 MIDI sequencer, the precursor to Cubase.

Notable hardware included various brands of MIDI cartridges, plug-in keyboards (such as the Color Tone or the Sound Chaser 64), Commodore's own SFX range which included a sound sampler and Sound Expander plug-in synthesizer and keyboard, the more recent Commodulator oscillator wheel and the Prophet 64 sequencer and synthesizer utility cartridge.

Recently a few professional musicians have used the Commodore 64's unique sound to provide some or all of the synthesizer parts required for their performances or recordings; an example being the band Instant Remedy. Also noteworthy is the Commodore 64 Orchestra who specialize in re-arranging and performing music originally composed and coded for the Commodore 64 games market. Its patron is celebrated Commodore composer Rob Hubbard.

CPU accelerators

Like the Apple II family, third-party acceleration units providing a faster CPU appeared late in the C64's life. Due to timing issues with the VIC-II chip - the same issues that caused the 1540 disk drive to be incompatible and the 128's "fast mode" to be 80 column-only - CPU accelerators for the 64 were much more complex and expensive to implement than for other computers. So while accelerators based on the WDC 65C02, usually running at 4 MHz, and on the 65816 at up to 20 MHz appeared, they appeared too late and were too expensive to gain widespread use.

The Turbo Master CPU, produced by Schnedler Systems, was a blue expansion port device which clocked in at 4.09 MHz. It also had a JiffyDOS option.

The most well-known accelerator for the C64 is probably Creative Micro Designs
Creative Micro Designs
Creative Micro Designs is a computer technologies company which today sells PCs and related equipment, but which started out in 1987 selling self-designed firmware updates and hardware for the Commodore 64 and C128 8-bit home/personal computers....

' SuperCPU
SuperCPU
The SuperCPU was developed by Creative Micro Designs, Inc. It is a processor upgrade for the Commodore 64 and Commodore 128 personal computer platforms. The SuperCPU uses the W65C816S 8/16 bit microprocessor. The unit can have up to 16 MB RAM installed. The unit sported a "Turbo" switch which, when...

, which gives the C64 a 20 MHz processor (instead of ~1 MHz) and up to 16 MB of RAM if combined with CMD's SuperRamCard. Understandably, due to a very limited "market" and number of developers, there has not been much software tailored for the SuperCPU to date— however GEOS
GEOS (8-bit operating system)
GEOS is an operating system from Berkeley Softworks . Originally designed for the Commodore 64 and released in 1986, it provided a graphical user interface for this popular 8-bit computer.GEOS closely resembled early versions of Mac OS and included a graphical word processor and paint program...

 was supported. Among the few offerings available include the GEOS-compatible operating system, Wheels
Wheels (operating system)
The Wheels operating system for the Commodore 64 and Commodore 128 home computers is partially based on and an upgrade from GEOS. Wheels gives new abilities to the C64 and 128: the ability to open several, movable, resizeable windows on the desktop and limited graphical web browsing...

; a Wheels-based web browser called "The Wave", a Unix/QNX-like graphical OS called Wings, some demos, various classic games modified for use with the SuperCPU, and a shooter game in the old Katakis
Katakis
Katakis is a side scrolling shooter style arcade game developed for the Commodore 64 by Rainbow Arts in 1987, and converted to the Commodore Amiga by Factor 5 in 1988. It was re-released as Denaris in 1989.-Introductory plot:...

-style called Metal Dust.

Present and Future devices

While CMD no longer produces Commodore hardware, new peripherals are still being developed and produced, mostly for mass storage or networking purposes.

The MMC64
MMC64
The MMC64 is a cartridge for the C64 home computer, which plugs into the expansion port. It was developed in 2005 by Oliver Achten, production and sale is done by the Commodore hardware accessory company Individual Computers, although the MMC64 is sold by other retailers as well.-Hardware...

 cartridge allows the C64 to access MMC- and SD flash memory
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...

 cards. And several revisions and add-ons have been developed for it to take advantage of extra features. It features an Amiga clock port
Clock port
The clock port is a commonly used term for the real-time clock interface of the Amiga 1200 computer. The port is a remnant of an abandoned design feature for addition of internal RAM and a clock for time keeping. However, it was later widely used as a general purpose expansion port by third-party...

 for connecting a RR-Net Ethernet-Interface, an MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...

 player add-on called 'mp3@c64' has even been produced for it.

In February 2008, Individual Computers started shipping the MMC Replay. It unites the MMC64 and the Retro Replay in one cartridge, finally built with proper case-fit in mind (even including the RRnet2 Ethernet add-on). It contains many improvements, such as c128 compatibility, a built-in .d64 mounter (not speedloader-compatible though, because the 1541 CPU is not emulated), 512KB ROM for a total of eight cartridges, 512kb RAM, a built-in flash-tool for cartridge images and wider support for various types of cartridges (not merely Action-replay-based).

In April 2008, the first batch of 1541 Ultimates shipped, a project by the hobbyist VHDL-developer Gideon Zweijtzer. This is a cartridge that carries an Action Replay and Final Cartridge (whatever the user prefers) and a very compatible FPGA-emulated 1541 drive that is fed from a built-in SD-card slot (.d64, prg etc). The difference to other SD-based and .d64 mounting cartridges like the MMC64, Super Snapshot 2007 or MMC Replay is, that the 6502
MOS Technology 6502
The MOS Technology 6502 is an 8-bit microprocessor that was designed by Chuck Peddle and Bill Mensch for MOS Technology in 1975. When it was introduced, it was the least expensive full-featured microprocessor on the market by a considerable margin, costing less than one-sixth the price of...

 that powers the 1541 Floppy and the 1541's mechanical behavior (even sound) is fully emulated, making it theoretically compatible with almost anything. Fileselection and management is done via a third button on the cartridge that brings up a new menu on screen. The 1541 Ultimate also works in standalone mode without a c-64, functioning just like a normal Commodore 1541
Commodore 1541
The Commodore 1541 , made by Commodore International, was the best-known floppy disk drive for the Commodore 64 home computer. The 1541 was a single-sided 170 kilobyte drive for 5¼" disks...

 would. Disk-selection of .d64s is then done via buttons on the cartridge, power is supplied via USB. There is a "Plus-Version" available with an extra 32 Megabytes of RAM (as REU and for future use), the basic version has just enough RAM for the advertised functions to work.
In October 2008, the second and third batch of 1541 Ultimates were produced to match the public demand for the device. The regular version without the 32MB RAM was dropped since there was no demand for it. Due to public demand there is also a version with Ethernet now.
In 2010 a completely new PCB and software has been developed by Gideon Zweijtzer to facilitate the brand new 1541-Ultimate-II cartridge.

The IDE64 interface cartridge
IDE64
The IDE64 interface cartridge is an expansion port device for connecting ATA devices to the C64 or C128 computers.-Hardware:There were several somewhat different versions of this cartridge over the years. The interface was designed by Tomas Pribyl and Jan Vorlicek in 1994...

 provides access to parallel ATA drives like hard disks, CD
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...

/DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

 drives, LS-120
SuperDisk
The SuperDisk, sometimes marketed as LS-120 and a later variant LS-240, is a high-speed, high-capacity alternative to the 90 mm , 1.44 MB floppy disk. The Superdisk hardware was introduced by 3M's storage products group circa 1997...

, Zip drives, and CompactFlash
CompactFlash
CompactFlash is a mass storage device format used in portable electronic devices. Most CompactFlash devices contain flash memory in a standardized enclosure. The format was first specified and produced by SanDisk in 1994...

 cards. It also supports network drives (PCLink) to directly access a host system over various connection methods including X1541, RS-232
RS-232
In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...

, Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....

 and USB
Universal Serial Bus
USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....

. The operating system called IDEDOS
IDEDOS
IDEDOS is a ROM-based disk operating system written in 6502/65816 assembly language for the Commodore 64, 128 and SuperCPU. Its main purpose is to control ATA devices connected to an IDE64 cartridge and present them like normal Commodore drives...

 provides CBM
Commodore International
Commodore is the commonly used name for Commodore Business Machines , the U.S.-based home computer manufacturer and electronics manufacturer headquartered in West Chester, Pennsylvania, which also housed Commodore's corporate parent company, Commodore International Limited...

/CMD
Creative Micro Designs
Creative Micro Designs is a computer technologies company which today sells PCs and related equipment, but which started out in 1987 selling self-designed firmware updates and hardware for the Commodore 64 and C128 8-bit home/personal computers....

 compatible interface to programs on all devices. The main filesystem is called CFS, but there's read-only support for ISO 9660
ISO 9660
ISO 9660, also referred to as CDFS by some hardware and software providers, is a file system standard published by the International Organization for Standardization for optical disc media....

 and FAT12/16/32
File Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...

. Additional features include BASIC extension
BASIC extension
BASIC toolkits —not to be confused with widget toolkits—were a common type of program for 1980s 8-bit home computers...

, DOS Wedge
DOS Wedge
The DOS Wedge was a popular piece of Commodore 64 system software. Written by Bob Fairbairn, it was included by Commodore on the 1541 disk drive Test/Demo Disk and also packaged with the C64 Macro Assembler...

, file manager
File manager
A file manager or file browser is a computer program that provides a user interface to work with file systems. The most common operations performed on files or groups of files are: create, open, edit, view, print, play, rename, move, copy, delete, search/find, and modify file attributes, properties...

, machine code monitor
Machine code monitor
A machine code monitor is software built into or separately available for various computers, allowing the user to enter commands to view and change memory locations on the machine, with options to load and save memory contents from/to secondary storage.Machine code monitors became something of a...

, fast loader
Fast loader
A fast loader is a software program for a home computer - most commonly, the Commodore 64 - that accelerates the speed of file loading from the floppy disk drive.- Background :...

, BIOS
BIOS
In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....

 setup screen.

Today's computer mice can be attached via the micromys interface that can process even optical mice and similar. There are also various interfaces for plugging the 64 to a PC keyboard.

A special board for converting Commodore 64 video signals to standard VGA monitor output is also currently under development, also there is a board under development to convert the Commodore 128's 80 column RGBI CGA-compatible video signal to VGA format, although no tangible product exists at this writing.

In September 2008, Individual Computers announced the Chameleon, a Cartridge for the Expansion Port that adds a lot of previously unseen functionality. It has a Retro-Replay compatible Freezer and MMC/SD-Slot, 16MB REU and a PS/2 connector for a PC Keyboard. Support for a network adapter and battery-backed real time clock exists. The cartridge does not even have to be plugged into a Commodore 64 and can be used as a standalone device using USB power. Since the cartridge essentially also includes a Commodore One it is possible to include a VGA Port that outputs the picture to a standard PC monitor. The Commodore One core also allows the cartridge to be used as a CPU accelerator, and a core to run a Commodore Amiga environment in standalone mode also exists. Unlike most other modern day c64 hardware, this cartridge actually ships with a bright yellow case. Shipping was announced for Q1/2009, and currently the cartridge is available, although the firmware is in a beta state.
A standalone mode docking station is under development.

Retro Innovations is shipping the uIEC device, which utilizes the core design of the SD2IEC project to provide a mass media solution for Commodore 8-bit systems that utilize the Commodore IEC Serial Bus. NKCElectronics of Florida is shipping SD2IEC hardware which uses the sd2iec firmware.

See also

  • Computers: Commodore 64
    Commodore 64
    The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...

    , VIC-20
    Commodore VIC-20
    The VIC-20 is an 8-bit home computer which was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the PET...

  • Floppy Drives: Commodore 1541
    Commodore 1541
    The Commodore 1541 , made by Commodore International, was the best-known floppy disk drive for the Commodore 64 home computer. The 1541 was a single-sided 170 kilobyte drive for 5¼" disks...

    , 1551
    Commodore 1551
    The Commodore 1551 was a floppy disk drive for the Commodore Plus/4 home computer. It resembled a charcoal-colored Commodore 1541 and plugged into the cartridge port, providing faster access than the C64/1541 combination...

    , 1570
    Commodore 1570
    The Commodore 1570 was a 5¼" floppy disk drive for the Commodore 128 home/personal computer. It was a single-sided, 170KB version of the double-sided Commodore 1571, released as a stopgap measure when Commodore International was unable to provide large enough quantities of 1571s due to a shortage...

    , 1571
    Commodore 1571
    The Commodore 1571 was Commodore's high-end 5¼" floppy disk drive. With its double-sided drive mechanism, it had the ability to utilize double-sided, double-density floppy disks natively. This was in contrast to its predecessors, the 1541 and 1570, which could fully utilize such disks only if the...

    , 1581
    Commodore 1581
    The Commodore 1581 is a 3½ inch double sided double density floppy disk drive made by Commodore Business Machines primarily for its C64 and C128 home/personal computers. The drive stores 800 kilobytes using an MFM encoding but format different from both MS-DOS , and the Amiga formats. With...


External links

  • Individual Computers
    Individual Computers
    Individual Computers is a German computer hardware company specializing in retrocomputing accessories for the Commodore 64, Amiga, and PC platforms. Individual Computers produced the C-One reconfigurable computer in 2003...

    - Makers of MMC64 and RR-series products
  • Protovision - Makers of various new hardware upgrades
  • Lemon64 - Includes some of the best Commodore 64 music software
  • Home Recording - Music discussion board thread linking to many others relevant to C64 music

Manuals

Commodore
CARDCO


The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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