Apollo to P82 – products side-by-side

Side-by-side parts comparison — four controllers: AGC, HP2116, our P82 with the HP9825 [INDEX]

Apollo AGC




Design of all is optimized towards control of equipment through an input/output (I/O) section with prioritized interrupt capabilities and dedicated instructions for a real-time operating environment. [The HP2116 however, was a general purpose computer and thus quickly spread into other areas.]

Logic cage


Display and Keyboard

P82 alongside the AGC ?

Design and construction of P82 was completely ground-up. From the metal work, through circuit design, and integration with the HP-9825 computer. We are not pretending that the project is comparable to landing on the moon (!) yet the fundamental principals of program, control and feedback in a real time environment do have much in common. The attic room was our space ship, which took off and landed wherever a “show” and our imagination would take us.


[Note on audio technology at the time the P82 was conceived: analog tape was the only accessible multi-channel media and, although studio PCM equipment was available it was not mainstream. Also the CD was not commercialised until 1983, and Sony’s digital audio tape [DAT] only in 1987.]

Instruction set / cycle time

41 / 11.7µs

68 / 1.6µs

50 / 60µs

59 / 800ns


Core RAM: 2k x 16 bits

Core “rope” ROM: 36k x 16 bits

Core RAM: 4k/8k x 17 bits


SRAM: 2k x 8 bits


R/W min 8k bytes exp to 32k

ROM min 24k bytes

Project timeline (concept – design – intro – exit)

1963 – 1963 – 1969 – 1975

1963 – 1966 – 1968 – 1971

1981 – 1982 – 1983 – 1987

1974 – 1976 – 1984 – 1988

HP-9825 taking a key supporting role in the 40 years anniversary of P82.