What is this about?
What happens, when a noob gets his fingers on very old computer hardware and decides to make it work again.
What happened?
The original plan was to collect and restore typical home computers of the late 80s and early 90s and to play the good old games from the youth. That means computers like the Commodore 64, Sinclair Spectrum, Atari etc. In search for old hardware I installed the app “Ebay Kleinanzeigen” (kind of the German version of Craigslist) on my phone, entered “Computer” into the search field and got this as very first hit:
Sunday, 07/05/20
HP PC,COMPUTER,PRINTER,OLDTIMER,BARNFIND
HP COMPUTER without monitor, incl. plotter…….. Fabrication Date 6/30/1978,defect
Price negotiable
Sure, this wasn’t a C64, and I certainly didn’t play games on stuff like this in my childhood. This was even better! It reminded me of my schooldays, when we had PASCAL lessons on a small UNIX mainframe from the 70s. Long story short: in the late afternoon I had those two beasts sitting on my kitchen table.
What is the plan?
Both machines shall be preserved for posterity in best possible condition. All features have to be functional again. The spare parts should be as close to the original as possible.
What is the problem?
I’m a noob. On one hand I always messed around with computers. I used home computers and PCs, coded, upgraded, swapped parts etc. But I never restored an old computer. The last time I soldered something was 30 years ago. My knowledge of electronic circuits is based on the physics lessons in school, and is more than rusty. It will cost me a lot of effort to learn everything it needs to repair those valuable machines. I don’t want to break something and make things worse.
Mission Goal
The HP9830 has to run a little BASIC program which outputs a Lissajous-figure to the plotter.