Galactic Expansion Board – Retro Computing

When I got a SYM-1 again, I needed to add ROMs, RAM and it would be nice to have the 1541 DOS finally operational (I had the documentation since 2000 and typed in the 1541 DOS source into TASM assembler source code).

I found this board on ebay and bought it. Well packaged, nice design with documentation.
It offers:
– RAM 32K for lower memory (62256)
– ROM for all known upper memory locations, loaded with Monotor, RAE, Basic and the 1541 DOS (28c256)
– power supply – audio interface and power switch and -5V
-SD2IEC interface with 16GB SD card
– a PIC18F27Q10 for glue logic and inverters for the IEC bus

A pity that the design make you loose access to the interface connectors.

Circuit diagram (from private communication with Bob from Galactic Studios)