Amiga custom chips
Encyclopedia
In addition to the Amiga chipsets, various specially designed chips
have been used in Commodore Amiga
computers that do not belong to the 'Amiga chipset' in a tight sense.
, 2000(B)
and CDTV. Gary provides glue logic
for bus control and houses supporting functions for the floppy disk drive. It integrates many functions built discretely in the previous Amiga 1000
in order to reduce costs.
and A4000/T
.
and A1200
. It also incorporates the control logic for the PCMCIA
and internal ATA interface on these systems.
for the Zorro II
expansion subsystem.
subsystems. Super Buster's development was never really finished, so there are various levels of compatibility:
All revisions fully support Zorro II PIO and DMA.
(Complex Interface Adapter) for peripheral interfacing and the system timers. These chips were also used in some other Commodore devices.
Officially, SDMAC rev 02 requires a Ramsey 04, and SDMAC 04 a Ramsey 07 counterpart. but SDMAC 04 + Ramsey 04 and even SDMAC 02 + Ramsey 07 combinations have been reported to work as well.
The previous 16-bit DMAC used in A2091/A590 SCSI adapters also includes 24-bit address generation.
expansion for the A2000. Amber buffers alternate video fields in three 256Kx4 field memory chips to convert
interlaced output to progressive format. Amber can accurately sample Lo-res and Hi-res modes but drops every other pixel in SuperHi-res (35 ns pixels) mode. Non 15 kHz modes are automatically bypassed to the monitor without buffering or changing frequencies. Amber was also designed to work without expensive field memory as a simple scan doubler, but has not been marketed that way.
, Budgie connects the trapdoor expansion port for Zorro II-like expansions and controls additional Fast RAM.
is the CD32
's all-purpose glue chip. It also houses the CD-ROM interface and a simple hardware-based chunky-to-planar pixel conversion.
for the OCS/ECS generation's 12 bit video to analogue RGB output. It also generates a monochrome composite video
signal and combined sync. The A3000 uses one Vidiot each for 15 kHz video and for 31 kHz (Amber) output. AGA Amigas use off-the-shelf
DACs.
is not a custom chip but a mask-programmed ROM chip
for most versions. It contains the largest part of the operating system
. Kickstart 1.x ROMs have a capacity of 256 KiB, Kickstart 2.x and 3.x contain 512 KiB. 32-bit Amigas use a pair of 16-bit chips to provide full width access. Later not mass produced upgrade versions were often realized with PROMs
or EPROMs.
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
have been used in Commodore Amiga
Amiga
The Amiga is a family of personal computers that was sold by Commodore in the 1980s and 1990s. The first model was launched in 1985 as a high-end home computer and became popular for its graphical, audio and multi-tasking abilities...
computers that do not belong to the 'Amiga chipset' in a tight sense.
Gary
Gary, short for Gate Array, has been used in the Amiga 500Amiga 500
The Amiga 500 - also known as the A500 - was the first “low-end” Commodore Amiga 16/32-bit multimedia home/personal computer. It was announced at the winter Consumer Electronics Show in January 1987 - at the same time as the high-end Amiga 2000 - and competed directly against the Atari 520ST...
, 2000(B)
Amiga 2000
The Amiga 2000, or A2000, is a personal computer released by Commodore in 1986. It is the successor to the Amiga 1000.-Features:Aimed at the high-end market, the original Europe-only model adds a Zorro II backplane, implemented in programmable logic, to the custom Amiga chipset used in the Amiga 1000...
and CDTV. Gary provides glue logic
Glue logic
In electronics, glue logic is the custom logic circuitry used to interface a number of off-the-shelf integrated circuits.This is often achieved using ordinary 7400- or 4000-series components. In more complex cases, programmable logic devices like a CPLD or FPGA might be used...
for bus control and houses supporting functions for the floppy disk drive. It integrates many functions built discretely in the previous Amiga 1000
Amiga 1000
The A1000, or Commodore Amiga 1000, was Commodore's initial Amiga personal computer, introduced on July 23, 1985 at the Lincoln Center in New York City....
in order to reduce costs.
Fat Gary
Fat Gary was Gary's upgrade for the 32-bit A3000/TAmiga 3000
The Commodore Amiga 3000, or A3000, was the third major release in the Amiga computer family. Released in June 1990, it features improved processing speed, improved rendering of graphics, and a new revision of the operating system...
and A4000/T
Amiga 4000
The Commodore Amiga 4000, or A4000, is the successor of the A2000 and A3000 computers. There are two models, the A4000/040 released in October 1992 with a Motorola 68040 CPU, and the A4000/030 released in April 1993 with a Motorola 68EC030....
.
Gayle
Gayle replaced Gary in the A600Amiga 600
The Amiga 600, also known as the A600 , is a home computer that was introduced at the CeBIT show in March 1992. The A600 was Commodore International's final model based on the Motorola 68000 CPU and the ECS chipset. It is essentially a redesign of the Amiga 500 Plus, with the option of an internal...
and A1200
Amiga 1200
The Amiga 1200, or A1200 , was Commodore International's third-generation Amiga computer, aimed at the home market...
. It also incorporates the control logic for the PCMCIA
PC Card
In computing, PC Card is the form factor of a peripheral interface designed for laptop computers. The PC Card standard was defined and developed by the Personal Computer Memory Card International Association which itself was created by a number of computer industry companies in the United States...
and internal ATA interface on these systems.
Buster
Buster is the expansion BUS conTrollER and was used in the Amiga 2000(B), integrating discrete logic from the original A2000(A). Buster controls bus arbitration and DMADirect memory access
Direct memory access is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit ....
for the Zorro II
Zorro II
Zorro II is the name of the general purpose expansion bus used by the Amiga 2000 computer. The bus is mainly a buffered extension of the Motorola 68000 bus, with support for bus mastering DMA. The expansion slots use a 100-pin connector and the card form factor is the same as the IBM PC...
expansion subsystem.
Super Buster (Fat Buster)
The Amiga 3000 and 4000 lines use Super Buster for bus control and arbitration of both Zorro II and Zorro IIIZorro III
Released as the expansion bus of the Commodore Amiga 3000 in 1990, the Zorro III computer bus was used to attach peripheral devices to an Amiga motherboard. Designed by Commodore International lead engineer Dave Haynie, the 32-bit Zorro III replaced the 16-bit Zorro II bus used in the Amiga 2000...
subsystems. Super Buster's development was never really finished, so there are various levels of compatibility:
- Level I - up to rev 7 (A3000), only provides support for basic Zorro III without DMA.
- Level II
- rev 9 (A4000) is slightly faster than Level I. It provides DMA support, but has a bug that might lead to a bus lockup.
- rev 11 (A4000T and aftermarket) provides DMA support for a single bus master. 16 MHz A3000 requires a 25 MHz upgrade for Buster11 to work.
All revisions fully support Zorro II PIO and DMA.
CIA
All Amiga computers use two 8520 CIAsMOS Technology CIA
The 6526/8520 Complex Interface Adapter was an integrated circuit made by MOS Technology. It served as a I/O port controller for the 6502 family of microprocessors, providing for parallel and serial I/O capabilities as well as timers and a Time-of-Day clock...
(Complex Interface Adapter) for peripheral interfacing and the system timers. These chips were also used in some other Commodore devices.
- 'Even' CIA functions: floppy control, serial control, some parallel port status
- 'Odd' CIA functions: parallel port, keyboard, some floppy support, joystick/mouse buttons.
Ramsey & (Super) DMAC
In the A3000 and A4000 series, Ramsey controls the on-board 32-bit Fast RAM and provides address generation for SDMAC. The SDMAC in the A3000/T provides DMA and bus interface for the integrated WD33C93A SCSI controller.Officially, SDMAC rev 02 requires a Ramsey 04, and SDMAC 04 a Ramsey 07 counterpart. but SDMAC 04 + Ramsey 04 and even SDMAC 02 + Ramsey 07 combinations have been reported to work as well.
The previous 16-bit DMAC used in A2091/A590 SCSI adapters also includes 24-bit address generation.
Amber
Amber was used in the A3000(T) and on the A2320 flicker fixerFlicker fixer
A flicker fixer or scan doubler is a piece of computer hardware that de-interlaces the output video signal. The purpose of a flicker fixer is to adjust a video signal prepared for TV to the needs of an ordinary CRT computer display....
expansion for the A2000. Amber buffers alternate video fields in three 256Kx4 field memory chips to convert
Deinterlacing
Deinterlacing is the process of converting interlaced video, such as common analog television signals or 1080i format HDTV signals, into a non-interlaced form....
interlaced output to progressive format. Amber can accurately sample Lo-res and Hi-res modes but drops every other pixel in SuperHi-res (35 ns pixels) mode. Non 15 kHz modes are automatically bypassed to the monitor without buffering or changing frequencies. Amber was also designed to work without expensive field memory as a simple scan doubler, but has not been marketed that way.
Budgie
Used in the A1200Amiga 1200
The Amiga 1200, or A1200 , was Commodore International's third-generation Amiga computer, aimed at the home market...
, Budgie connects the trapdoor expansion port for Zorro II-like expansions and controls additional Fast RAM.
Bridgette
Bridgette is an integrated bus buffer in the A4000 series. It connects the chip, CPU and I/O buses.Akiko
AkikoAkiko (Amiga)
Akiko is a custom chip used in the Amiga CD32 games console and forms part of the AGA chipset used in that system. Akiko is responsible for implementing system glue logic, some of the control logic for the CD32's CD-ROM controller, and controlling the serial port .Additionally, the Akiko chip is...
is the CD32
Amiga CD32
The Amiga CD32, styled "CD32" , was the first 32-bit CD-ROM based video game console released in western Europe, Australia, Canada and Brazil. It was first announced at the Science Museum in London, United Kingdom on 16 July 1993, and was released in September of the same year...
's all-purpose glue chip. It also houses the CD-ROM interface and a simple hardware-based chunky-to-planar pixel conversion.
Vidiot
The Vidiot is a hybrid integrated circuit that works as digital-to-analog converterDigital-to-analog converter
In electronics, a digital-to-analog converter is a device that converts a digital code to an analog signal . An analog-to-digital converter performs the reverse operation...
for the OCS/ECS generation's 12 bit video to analogue RGB output. It also generates a monochrome composite video
Composite video
Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...
signal and combined sync. The A3000 uses one Vidiot each for 15 kHz video and for 31 kHz (Amber) output. AGA Amigas use off-the-shelf
Commercial off-the-shelf
In the United States, Commercially available Off-The-Shelf is a Federal Acquisition Regulation term defining a nondevelopmental item of supply that is both commercial and sold in substantial quantities in the commercial marketplace, and that can be procured or utilized under government contract...
DACs.
Kickstart
The Kickstart ROMKickstart (Amiga)
Kickstart is a commonly used term for the bootstrap firmware of the Amiga computers developed by Commodore.Most Amiga models were shipped with the Kickstart firmware stored on ROM chips...
is not a custom chip but a mask-programmed ROM chip
Mask ROM
Mask ROM is a type of read-only memory whose contents are programmed by the integrated circuit manufacturer...
for most versions. It contains the largest part of the operating system
AmigaOS
AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000...
. Kickstart 1.x ROMs have a capacity of 256 KiB, Kickstart 2.x and 3.x contain 512 KiB. 32-bit Amigas use a pair of 16-bit chips to provide full width access. Later not mass produced upgrade versions were often realized with PROMs
Programmable read-only memory
A programmable read-only memory or field programmable read-only memory or one-time programmable non-volatile memory is a form of digital memory where the setting of each bit is locked by a fuse or antifuse. Such PROMs are used to store programs permanently...
or EPROMs.
See also
- Amiga Original chipset (OCS)
- Amiga Enhanced ChipsetEnhanced Chip SetThe Enhanced Chip Set is the second generation of the Amiga computer's chipset, offering minor improvements over the original chipset design. ECS was introduced in 1990 with the launch of the Amiga 3000. Amigas produced from 1990 onwards featured a mix of OCS and ECS chips, such as later versions...
(ECS) - Amiga Advanced Graphics Architecture (AGA)