The IBM 4020 Military Computer was a Cold War era military computer. Two of them were used in the two

IBM AN/FSQ-31 SAC Data Processing System The IBM AN/FSQ-31 SAC Data Processing System (FSQ-31, Q-31, colloq.) was a USAF command, control, and coordination system for the Cold War Strategic Air Command (SAC). IBM's Federal Systems Division was the prime contractor for the AN/FSQ-31s, ...

s. Details: * Instruction rate : Up to 400,000 instructions per second * Cycle time : 2.5 microseconds * Word size : 48 bits + 2 parity bits * Core storage : up to 131,072 words * operates in parallel mode * 69 instructions * single address instructions * Add or subtract : 2.5 microseconds (fixed point) * Add or subtract : (floating point) * Multiply : average 24 µs (24 bit precision fixed point) * Multiply : (floating point) * Multiprocessing with Automatic Priority The instruction format includes: * 7 bit op code * 2 bit real data indicator * 3 bit byte displacement * 3 bit mode selector * 1 sign bit * 8 bit 'byte activity' * 1 bit Double index flag * 1 bit Indirect address flag * 4 bit index register selection * 18 bit address. Man-machine communications included a light-gun to indicate an area of interest on a

visual display unit A computer monitor is an output device that displays information in pictorial or textual form. A discrete monitor comprises a visual display, support electronics, power supply, housing, electrical connectors, and external user controls. The ...

. Circuit logic packaging was based on 7 types of Q-pacs each holding 1 to 4 circuits. Transistors and semiconductor diodes were soldered to the outside of the Q-pac encapsulation for ease of cooling and replacement.

References

IBM transistorized computers Military electronics of the United States 48-bit computers {{US-mil-stub, date=May 2014