IBM 4020 Military Computer

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 Systems.
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
Add or subtract :
Multiply : average 24 μs
Multiply :
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.
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.