SDS 930

The SDS 930 is a commercial 24-bit computer using bipolar junction transistors sold by Scientific Data Systems. It was announced in December 1963, with first installations in June 1964.

An SDS 930 system consists of at least three standard (30 cu. ft.) cabinets, comprising the arithmetic and logic unit, at least 8,192 words (24-bit + simple parity bit) magnetic core memory, and the IO unit. Two's complement integer arithmetic is used. The machine has integer multiply and divide, but no floating point hardware. An optional correlation and filtering unit (CFE) can be added, which is capable of very fast floating point multiply-add operations (primarily intended for digital signal processing applications).

A free-standing console is also provided, which includes binary displays of the machine's registers and switches to boot and debug programs. User input is by a Teletype Model 35 ASR unit and a high-speed paper tape reader (300 cps). Most systems include at least two magnetic tape drives, operating at up to 75 inches/second at 800 bpi. The normal variety of peripherals is also available, including magnetic drum units, card readers and punches, and an extensive set of analog-digital/digital-analog conversion devices. A (vector mode) graphic display unit is also available, but it does not include a means of keyboard input.

The SDS 930 is a typical small to medium scale scientific computer of the 1960s. Speed is good for its cost, but with an integer add time of 3.5 microseconds, it is not in the same league as the scientific workhorses of the day (the CDC 6600, for example). A well equipped 930 can easily exceed 10 cabinets and require a 300-500 sq. ft. climate controlled room. The price of such a system in 1966 would be in the neighborhood of $500K.

Programming languages available include FORTRAN II, ALGOL 60, and the assembly language known as Meta-Symbol. The FORTRAN system is very compact, having been designed and implemented by Digitek for SDS to compile and run in 4,096 word SDS 900 series machines. To do anything useful in such small memory space, the compiler relies on an SDS architectural feature known as Programmed OPeratorS, or POPS. This feature consists of a single bit in the instruction word that causes the machine to "mark place and branch" to the memory address of the instruction code value plus 100 (octal). As a result, pseudo instructions can be defined and implemented yielding very compact special-purpose code. Both the FORTRAN compiler and runtime take advantage of this capability.

...
Wikipedia