Apollo to P82 — 3 projects 4 products |

Reality

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 For historical reference, there is a 25MB hard drive with a clean, pressurized helium environment.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.

The HP 2116 computer designed with core memory and CTL logic from Fairchild semiconductor — HP180A oscilloscope: essential tool for development of logic circuitry, as in the P82 project. The 180A scope was available as of the late 1960’s and was the first screen that we hooked up to the 2116 computer via a dual digital to analog output interface card. Someone developed a program to display cards for the game of solitaire; player input was via the teletype keyboard or front panel switches !

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.