Odd Software for Odd Jobs

6502 Single Board Computer

I've finally finished assembling a 6502-based single board computer that I got on eBay. The board was designed by a fellow in Newcastle and is based on the SYM-1 from the early 80s.

2017-05-03 20.37.39

It was pretty simple to build - I had most parts lying around, including a 6502A that I pulled from a BBC Model B I've got. Mike, who designed this mini SBC, kindly helped out with some of the parts I didn't have - a 2732 4KB EPROM (smallest I had was 2764) with the SYM-1 Monitor programmed, the GAL chip (he also programmed, saving me some time figuring out how to get that done!) and the RAM chip.

The slowest crystal oscillator that Jaycar had was 2MHz, so I ordered a 1MHz part from the UK. And the 6532 was the last part to arrive from France.

I connected it to my Mac via a USB-TTL cable (which also supplied the +5V power) and it worked first time - connected at 4800 Baud and tried the sample program (sorry, app) out.

2017-05-04 06.33.17

SYM-1 program