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.

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.