[walnutclosefarm]

Seeing his list of restored devices, including an HP2645, recalled to me how we hacked the original HP2640A glass teletypes to turn them into little desktop computers. 2640s came with a set of self-tests that you could run from an HP3000 minicomputer. Didn't take us kids long to figure out that the role of the HP3000 was to download a string of bytes representing 8008 code, that the terminal ran to test itself. They had 1K byte and 4k byte memory cards in the terminal. So we reverse engineered the 8008s interface to the screen and keyboard IO system, and were soon building little screen games. This was 2 years before the Apple II debuted, and when the only "home" computers you could get were big boxes like the Altair 8800. We basically had stumbled across the PC, but weren't smart or ambitious enough to do anything besides play dumb screen games with it.

[krallja]

I got an HP 4951b serial protocol analyzer off eBay, and want to do something similar with it. It’s based on an NSC-800 CPU, which feels like a cross between a Z80 and an i8085. My explorations are at https://github.com/InPermutation/HP4951b

[tomcam]

How cool! What kind of games?

[walnutclosefarm]

Most of our effort went into a solitaire version of pong, where you used arrow keys to move the "bat" along the bottom of the screen, and the "ball" ricocheted symmetrically off the top. If I recall correctly, the ball sped up over time, and we introduced some randomness in ricochet to make it a challenge you'd eventually lose. But honestly, it was a long time ago, so how much of what I remember actually worked well, I wouldn't bet.

It did teach me 8008 assembler though. Used that later build a primitive RT OS with multi-level interrupts that operated a cross-bar switch for connecting KSR 33 teletypes to different computers in the lab. That was fun. We wrote the OS in concurrent pascal pseudo-code, then hand compiled into assembler.

[tomcam]

Very fun story, thanks.

> We wrote the OS in concurrent pascal pseudo-code, then hand compiled into assembler

I love low level programming, but I never considered that technique back in the day. Kind of brilliant.