My very first computer was a KIM-1 (bought in 1978, almost exactly 40 years ago) and my first job at Franklin Computer was writing 6502 assembly code, so I’ve been a fan of the 6502 for a long time.
Recently I was toying with the idea of an SS-50 CPU board with a 6502, but then decided a 65C02 would be a better option. The 6502 started as a copy of the 6800 so it was easy getting it onto the SS-50 bus.
This is the result:
I’m not really planning on this being a product soon, as it was more of an experiment. Besides the board, I also needed to develop a monitor (CTMON65) to allow the console to do things. Basic specs:
- 65C02 running at 2 MHz.
- RAM from 0000-7FFF.
- RAM can be enabled in 4K blocks from 8000-EFFF. Allows positioning RAM around the SS-50 I/O ranges for either a 6800 or 6809.
- Baud rate generator for 1200, 2400, 4800 and 9600 baud.
- 28C64, 28C128 or 28C256 EEPROM. Jumpers select the high order address bits so up to four monitors can be in EEPROM.
- The regions from E000 to EFFF can be RAM, ROM, or not enabled (I/O for 6809).
- Includes a software driven single-step function, exactly like the KIM-1 does it. Monitor functions do all the work.
- Monitor (CTMON65) supports all the usual stuff, including support for the SD Card System.
The monitor has been going through some re-writes and isn’t ready for doing much. There are a lot of software projects on my to-do list, this being one of them.
At this point, this isn’t a product, as I don’t think there is much demand. The 6502 never had a dominant OS except for machine-specific ones, so there is no generic OS I can simply write drivers for and have it work.
Anyway, this was my fun project recently. I’ll probably have it at VCF MW next month.