CDC 1700

Hardware

The 1700 uses ones' complement arithmetic and an ASCII-based character set, and supports memory write protection on an individual word basis. It has one general-purpose register and two indexing registers (one of which was implemented as a dedicated memory location). The instruction set is fairly simple and supports seven storage addressing modes, including multilevel (chained) indirect addressing.

Although described as a 16-bit system, the basic core storage memory is 4,096 18-bit words, each comprising

• 16 data bits
• a parity bit, and
• a program protection bit; memory could be expanded to 32,768 words; I/O was in units of 8 or 16 bits.

Peripherals

Available peripherals included teletypewriters, paper tape readers/punches, punched card readers/punches, line printers, magnetic tape drives, magnetic drums, fixed and removable magnetic disk drives, display terminals, communications controllers, Digigraphic display units, timers, etc. These interfaced to the processor using unbuffered interrupt-driven "A/Q" channels or buffered Direct Storage Access channels.

Software

The main operating systems for the 1700 were the Utility System, which usually took the form of several punched paper tapes (resident monitor plus utilities), a similar Operating System for larger configurations (often including punched cards and magnetic tape), and the Mass Storage Operating System (MSOS) for disk-based systems.

An assembler and a Fortran compiler were available. Pascal was also available, via a cross compiler on a CDC 6000 series host. The Cyber 18 series, exploiting the extended instruction set, ran a disk-based OS, the Interactive Terminal Oriented System (ITOS). This system supported Fortran, Cobol, and UCSD Pascal. ITOS was a foreground/background system with multiple users connected via serial CRT terminals; user tasks ran in the background while the operating system itself ran in the foreground.

Market acceptance

The 1700 series found use as communications concentrators, Digigraphics workstations, remote batch job entry stations, and industrial process controllers.{{cite journal |title=CDC 1700 FORTRAN for Process Control

Washington, D.C. used a Control Data 1700 in vote-tallying."It was decided to change the program of the CDC 1700. Changing the program without a public test May violate the spirit if not the letter of the D.C. Rules. {{cite book

Simulation

In mid-2016, John Forecast added a CDC 1700 simulator to the SIMH package.{{cite web

Photos

• CDC 1700 Control Panel
• Control Data 1700

References

Philips Technical Review, Volume 36, 1976, No., p.162 ff. Computer-aided design by Peter Blume: An early application of the CDC 1700 Digigraphic: shows in Fig. 4 a complete schematic of the computer configuration and in Fig. 5 a picture of the Digigraphic display Abstract:.... Work has been in progress at the Philips Laboratories in Hamburg since 1973 ... on an integrated computer system in which parts are completely detailed in a dialogue between the designer and a computer via an "interactive display" ...

The mentioned display is the display of the CDC 1700 Digigraphic. Fig. 4 Figure caption: The CDC 1700 Digigraphic computer system for the graphic processing of data. The interactive display is connected to the CD 1704 central processor via a control unit with a "picture store"; the computer itself has the usual mass stores and peripheral equipment. Information from the computer store can be displayed on the screen of the picture tube and can be altered or added to by using a light pen and keyboards connected to the interactive display. This means that very fast input of both alphanumeric and graphic information is possible, while the input can be verified immediately on the screen.

References

1. (1977). "CDC Cyber 18 Processor With MOS Memory, Macro Level System Description". CDC.