IBM 7094

The IBM 7094 the fourth member of the mostpopular family of IBM 's largesecond-generation transistorized mainframe computers and wasdesigned for "large-scale scientific and technological applications". The first 7094 installation was in September 1962 . In April 1964 , the first 7094 II was installed, whichhad almost twice as much general speed as the earlier IBM 7090 due to a fasterclock cycle and introduction of overlapped instruction execution.

NASA used 7094s to control the Mercury and Gemini space flights. Apparently, the US AirForce retired the last 7094s in service from the Ballistic Missile Early Warning System ("BMEWS") in the 1980s after almost 30 years of use.

Instruction Format

The basic instruction format was a 3-bit prefix, 15-bit decrement, 3-bit tag, and 15-bitaddress. The prefix field specified the class of instruction. The decrement field often contained an immediate operandto modify the results of the operation, or was used to further define the instruction type. The three bits of the tag specifiedseven index registers , the contents of which weresubtracted from the address to produce an effective address. The address field eithercontained an address or an immediate operand.