Commodore SX-64 Portable Computer

The Commodore SX-64 has the same basic design as the Commodore 64, but incorporates the monitor and a floppy diskette drive into a single chassis. The electronics are spread across three circuit boards in the chassis making service a challenge.

This diagram shows the individual circuit boards in the SX-64 and the cables an connectors that interconnect the boards.

Design Notes:

CPU Board

There are three EPROMs/PROMs on the board

  1. UD1, Character Generator ROM, P/N C 901225-01, 0x?000-0x?FFF

  2. UD3, Kernal ROM, P/N C 251104-04, 0xE000-0xFFFF

  3. UD4, BASIC ROM, P/N C 901226-01, 0xA000-0xBFFF

When the 6510 CPU is powered on and the 555 timer lets go of the