After a lengthy break I'm back to the UPNOD series. This time we'll take a closer look at the dynamic random-access memory (DRAM) circuitry present on the PCB:
As usual, all of my findings can be found here.Continue reading
A second installment in the UPNOD series, this time we'll take a look into the reset circuitry of the telco card.
As the title implies, this circuit is responsible for generating a proper Z80' reset sequence. Z80, being a rather dumb piece of clever electronics, may boot up in an undesirable undefined state and requires a few cycles of special treatment to properly initialize internal register values. This circuit does just that - it generates the initial reset pulse and handles reset signals coming from other parts of the board, all while maintaining proper synchronization.Continue reading
Cranking out another post took me way longer than I had anticipated when I rebooted this blog, but I got sidetracked by another quick hardware project that turned out to be way more involved and equally more fun than I originally thought...
I've designed an Atari 400/800/XL/XE standard cartridge compatible board that can hold up to 127 different standard 8KB and 16KB game ROMs at the same time. It's memory chip agnostic and features software game selection & a few neat hacks.Continue reading
Since my last actual post on this blog I have acquired a new class of hobbies - electronics. Most recently, reverse engineering of really old computers. This series of posts will be about a vintage eighties TelCo computer-card-thing marked UPNOD CARD0117 TN64 I bought on a local auction:
All my findings will be posted on this blog and the accompanying data will be gathered in this GitHub repository.Continue reading