Apollo to P82 — 3 projects 4 products


Presenting the Apollo Guidance Computer (AGC) alongside the HP2116 and our own P82 — Visual Overview. [index] [all posts]

1969 moon landing

1969 moon landing — project began in 1963, RTL logic, core memory and core “rope” ROM. Human interface was the “DSKY” – display and keyboard. This was the Apollo guidance Control computer or AGC.

There were no printed circuit boards, but double 3-input NOR gates assembled in modules of 120 IC’s (= 240 gates) welded to 4 rows of connection pins.

Each such module had thus no inherent functionality until plugged into the back-plane. Functionality was determined by the wire-wrapping connections of the back-plane which in fact connected each of the individual NOR gates into operational logic circuitry.

The I/O functionality to connect to the many controls and status of the space craft was very specific, sometimes simple in nature, yet totally real time — incorporating sophisticated interrupt, prioritizing and sharing approaches.

1969 HP2116 computer

1969 HP2116 computer — project began in 1963, . Human interface was the teletype, switch register and panel lights. It was one of the very first 16-bit commercial computers; introduced as an instrument controller at the insistence of Bill Hewlett, but was in fact a general purpose computer which the market itself forced into much broader areas.

Already here, the 2116 finds itself at the heart of a time-share system and interfaced to an HP high speed vacuum column tape drive. For historical reference, there is a 25MB hard drive with a clean, pressurized helium environment. Now in 2022 helium for very high density discs is back in vogue — less air resistance and extended life.

2116 had dual-sided PC boards, CTL IC’s with multi-gate logic from Fairchild semiconductor (model A introduced in 1966). Each logic board had specific functionality, plugged into wire-wrap back-plane. First models had 4k or 8k of 16-bit word (+parity) memory.

Extensive I/O designed with priority interrupt servicing for interfacing to external equipment in a real-time environment.

1982 – our P82 project

1982 P82 project by marcomathieumedia — CMOS IC’s with multi-function logic and small solid state memory. Human interface was similar to the AGC, meaning a chunky keyboard and a display (4 digits plus LEDs). IC’s are typically higher in density than the 2116. However IC’s are inserted into sockets which use back-plane wire-wrap as in the AGC.
P82 was a programmable controller, rather than a computer. Major comparisons made here are with the logic generation used, the human interface, and the wire-wrap back-plane build method.

In 1976 we had purchased an HP-9825 computer, to which we added a 16-bit parallel I/O capability for emulation of logic circuits during the design and prototyping of the P82. It also became an an integral part of P82’s extended operational capabilities. HP9825 was a powerful engineering and scientific computer with its own (HPL) high level programming language. It was built around a proprietary NMOSII 16-bit processor (24,000 transistors) about 10 years ahead of its time. It hosted similar register instructions and I/O architecture to that of the 2100 series.