saundby.com: RCA 1802

Low Power, Large Register File, Runs Without ROM, What's Not to Love?



The 1802 Processor in a simple test circuit. Lookit them little lights blink!

My First Microprocessor

My first computer was an Elf built around the 1802 processor. I still like to use it in circuits today!

1802 Free Run Circuit:

Here's a schematic (PDF) for the simple circuit in the picture at the top of the page.

It allows you to see the 1802 run through its address space, as every instruction decodes to a "NOP" (no operation). It's also a decent starting point for a more complex circuit that actually does something.

If you want the ultimate 1802 Blinky Circuit, check out the one by Lee Hart. It's available in the files section of the Yahoo! CosmacElf Group.

Membership Card:

I'm working on a Membership Card computer designed by Lee Hart around the 1802 CPU.

Other things keep intervening, and I'll admit I've complexified the project by putting it in a steampunk-ish tin with home made switch handles and glass crystals over the LEDs and so on. My board is one from the initial run. I'm really looking forward to finishing it. Really, I've got no excuse for not having done so, just that I keep too many things going at once. Right now the assembly area is occupied by two amateur radios that I'm making room for elsewhere (my new ham shack area.) Once that's clear, it should be a matter of just sitting for a few hours to finish assembly, all the bits and pieces are there now.

Dave Ruske's 1802 Websites:

No 1802 web page is complete without mention of Dave Ruske's wonderful COSMAC Elf web page and TinyElf software emulation of the original Elf.