RCA Spectra 70
Encyclopedia
Electronic data processing
Electronic Data Processing can refer to the use of automated methods to process commercial data. Typically, this uses relatively simple, repetitive activities to process large volumes of similar information...
(EDP) equipment manufactured by the Radio Corporation of America
RCA
RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...
’s computer division beginning in April 1965. The Spectra 70 line included several CPU models, various configurations of core memory, mass-storage devices, terminal equipment, and a variety of specialized interface equipment.
The system architecture and instruction-set were largely compatible with the non-privileged instruction-set of the IBM System/360. While this degree of compatibility made some interchange of programs and data possible, differences in the operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
software precluded transparent movement of programs between the two systems.
System Overview
Four models of the Spectra 70 CPU were offered in 1965, ranging from a small system (70/15) to the large scale (70/55.) Some of the main features were:- The systems were upward-compatible, allowing programs written for a smaller model to run on any larger machine in the series.
- Larger machines in the series were also faster, with memory access times ranging from two microsecondMicrosecondA microsecond is an SI unit of time equal to one millionth of a second. Its symbol is µs.A microsecond is equal to 1000 nanoseconds or 1/1000 millisecond...
s in the 70/15 to 0.84 microseconds in the 70/55. - Memory capacities ranged from a minimum of 4,096 bytes in the 70/15 to a maximum of 524,288 bytes in the 70/55.
- All used the Extended Binary Coded Decimal Interchange Code (EBCDICEBCDICExtended Binary Coded Decimal Interchange Code is an 8-bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems....
) of eight bits plus parity for internal data representation. - The use of a standard electrical interface allowed the same peripherals to be used with any CPU model in the series.
- Simultaneous input and output was accomplished by the use of intelligent communication channels. Like the IBM 360, two types of channel were available (on all but the 70/15): selector channels which could address up to 256 devices (one at a time), and multiplexerMultiplexerIn electronics, a multiplexer is a device that selects one of several analog or digital input signals and forwards the selected input into a single line. A multiplexer of 2n inputs has n select lines, which are used to select which input line to send to the output...
channels (not on the 70/15) which could simultaneously address up to 256 channels by time-sharing the channel.
Model 70/15
The RCA Model 70/15 was a small-scale processorCentral processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
that could still support a variety of applications
Application software
Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with...
. Memory limitations and relatively low processing speed made its use as a stand-alone computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
system somewhat impractical.
The 70/15 was often used as a satellite processor for larger systems or used as an intelligent terminal
Computer terminal
A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system...
for remote job entry. Typical applications of a satellite processor would include card-to-tape conversion
Analog-to-digital converter
An analog-to-digital converter is a device that converts a continuous quantity to a discrete time digital representation. An ADC may also provide an isolated measurement...
, card/tape-to-printer report generation, tape-to-card punching
Punched card
A punched card, punch card, IBM card, or Hollerith card is a piece of stiff paper that contains digital information represented by the presence or absence of holes in predefined positions...
, input pre-processing and verification, or tab-shop tasks like file sorting
Sorting
Sorting is any process of arranging items in some sequence and/or in different sets, and accordingly, it has two common, yet distinct meanings:# ordering: arranging items of the same kind, class, nature, etc...
, merge
Merge algorithm
Merge algorithms are a family of algorithms that run sequentially over multiple sorted lists, typically producing more sorted lists as output. This is well-suited for machines with tape drives...
, and data selection.
Two memory configurations for the 70/15 were available: either 4,096 bytes or 8,192 bytes of core memory. The memory cycle time for a 70/15 was 2 microseconds per byte of information.
Model 70/25
The RCA Model 70/25 was a small-to-medium scale computer system that supported a wider variety of applications, including use as a free standing system. In large installations, the 70/25 might also be used as a subsystem in a multi-processor complex. High throughputThroughput
In communication networks, such as Ethernet or packet radio, throughput or network throughput is the average rate of successful message delivery over a communication channel. This data may be delivered over a physical or logical link, or pass through a certain network node...
was facilitated by the use of fast memory and multiple simultaneous input/output streams. Equipped with selector channels and a multiplexer
Multiplexer
In electronics, a multiplexer is a device that selects one of several analog or digital input signals and forwards the selected input into a single line. A multiplexer of 2n inputs has n select lines, which are used to select which input line to send to the output...
channel, the 70/25 could concurrently operate eight low-speed devices in addition to eight high-speed devices.
Memory capacities for the 70/25 ranged from a minimum of 16,384 bytes to a maximum of 65,536 bytes. The memory cycle time was 1.5 microseconds to access one 8 bit byte.
Model 70/45
The RCA Model 70/45 was a medium scale processor of relatively good performance for its time. A floating-pointFloating point unit
A floating-point unit is a part of a computer system specially designed to carry out operations on floating point numbers. Typical operations are addition, subtraction, multiplication, division, and square root...
processor was available as an option and the 70/45 was considered suitable for commercial, scientific, communications, and real-time applications.
With a communications multiplexer, the 70/45 could accommodate up to 256 communication lines for interactive use as well as batch processing
Batch processing
Batch processing is execution of a series of programs on a computer without manual intervention.Batch jobs are set up so they can be run to completion without manual intervention, so all input data is preselected through scripts or command-line parameters...
. Thus, the 70/45 was ideal as the core of a multi-system installation. The 70/45 was one of the first computer systems to use monolithic integrated circuits in its construction. This level of integration was to become the defining characteristic of third-generation computers
History of computing hardware (1960s-present)
The history of computing hardware starting at 1960 is marked by the conversion from vacuum tube to solid state devices such as the transistor and later the integrated circuit. By 1959 discrete transistors were considered sufficiently reliable and economical that they made further vacuum tube...
.
Memory capacity for the 70/45 ranged from a minimum of 16,384 bytes to 262,144 bytes. The memory cycle time was 1.44 microseconds to access two bytes (one half word) of information.
Model 70/55
The RCA Model 70/55 was a medium-to-large scale processor with excellent processor characteristics well suited to both scientific and large-scale commercial processing. The 70/55 maintained a high-throughput capability by offering up to 14 simultaneous job-streams. Like the 70/45, the Model 70/55 made extensive use of monolithic integrated circuits.Memory capacity for the 70/55 ranged from 65,536 bytes of core memory to 524,288 bytes. The memory cycle time was 0.84 microseconds to access four bytes of information.
Input/Output Devices
Input-output devices on the Spectra 70 series were specifically designed to interface with all models of the Spectra processor using the RCA Standard Interface. Initial product offerings in 1965 included:- Card punches that were fully buffered and able to operate at 100 or 300 cards per minute, depending upon the specific model.
- Three models of printersComputer printerIn computing, a printer is a peripheral which produces a text or graphics of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most new printers, a...
were offered: a medium-speed printer running at 600 lines per minute, a high-speed printer running at 1,250 lines per minute, and a bill-printer running at 600 lines per minute on continuous forms and 800 lines per minute on card-stock. Like the card punches, the printers were fully buffered. - The Spectra optical card reader was able to read at up to 1,435 cards per minute with optional mark-sense reading available.
- Paper-tape capability was offered with 5, 6, 7, or 8 channel tape punches and readers. The punched tape reader operated at 200 characters per second and the tape punch ran at 100 characters per second.
- Three versions of magnetic tapeMagnetic tapeMagnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
were available running at 30, 60, or 120 kilobytes per second. In purely numeric mode, the tape reading and writing was performed at 240,000 digits per second. All tape drives were “industry” (meaning IBMIBMInternational Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
) compatible and contained automatic error-checking systems. Either 7 or 9 channel tape code could be used and tapes could be written in the forward direction and read in both forward and reverse directions. - Mass storageMass storageIn computing, mass storage refers to the storage of large amounts of data in a persisting and machine-readable fashion. Devices and/or systems that have been described as mass storage include tape libraries, RAID systems, hard disk drives, magnetic tape drives, optical disc drives, magneto-optical...
was available in the form of both magnetic drum and magnetic disc with an interchangeable disc-pack capacity of 7.25 MBMegabyteThe 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...
at a data interchange rate of 156 kbit/s. The high-speed drum had a capacity of 1 MBMegabyteThe 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 an average access timeAccess timeAccess time is the time delay or latency between a request to an electronic system, and the access being completed or the requested data returned....
of 8.6 milliseconds. - The Videoscan Document Reader was an optical character recognitionOptical character recognitionOptical character recognition, usually abbreviated to OCR, is the mechanical or electronic translation of scanned images of handwritten, typewritten or printed text into machine-encoded text. It is widely used to convert books and documents into electronic files, to computerize a record-keeping...
scannerImage scannerIn computing, an image scanner—often abbreviated to just scanner—is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop scanner where the document is placed on a glass...
with a speed of 1,300 documents per minute. This was primarily used to scan checks and similar transaction documents.