Category: Retrocomputing
-
Timing concerns of delay line style memory
I was getting bent out of shape that I needed to somehow reconstruct the system clock out of the data stored inside a delay line. But fooling around with an old discrete delay line simulation in a circuit simulator by replacing the giant stack of flip flops with a proper length delay line shows that…
-
National Semiconductor 4510 Mathematician
I have a small collection of vintage calculators that I stumbled into collecting. I found one at a garage sale, and then one was given to me, then I found a neat one on eBay for a good price… Before I knew it, I was a calculator collector. I actually use most of them despite…
-
Book recommendation: Turing’s Cathedral by George Dyson
If you’re interested in the early history of computing, check out Turing’s Cathedral by George Dyson. It covers an interesting middle phase between the original electronic digital computers and the wide commercialization of computers in the late 50s. Specifically it examines the people and development around “the IAS machine” at the Institute for Advanced Study…
-
Z80 Single Board Computer
Because the first assembly language I learned was for my TI graphing calculator, I’ve have a soft spot for the Z80 CPU. It’s a nice 8 bit architecture and widely used in pre-MSDOS machines. The Apple II used a 6502 but more or less all the “business class” machines ran CP/M on a Z80. It…
-
Kaypro BIOS
I’ve recently gotten back into retro computing in the IBM XT clone genre. I obtained a set of Kaypro PC-compatible boards – a CPU card, a backplane, and a RAM card. I’ve been slowly working with them to build a 8088-based PC of the late 80’s. My CPU card came with a BIOS that isn’t…