Weekend Project: MULTICOMP KIM-1 add-on

The KIM-1 by MOS Technology (later Commodore) was basically the first "development" system available to hobbyists. It used the new MOS 6502 CPU, 1 Kilobyte RAM, 2x 1 Kilobyte ROMs, 30 digital I/O lines (15 available for user expansion), fully available address and data buses, Teletype interface and audio casette tape interface. It came with full documentation, explained circuit diagram and full source code (assembler listing of the ROMs).

The original

Well, I once owned a real MOS technology made model, gave it away and later (out of nostalgia) aquired a later Commodore made model. This was made in 1977!

Unfortunately it started acting erratic a few years ago and finally stopped to work. Now it is a non working display item.

The "Clone"

During XMAS 2015, I got bored again and designed this board, which connects to the 40 pins of the MULTICOMP.

Using a 6502 core, writing a simple 6530 IO, ROMizing the KIM-002 binary into the FPGA and assigning the external SRAM to every remaining address, this might be the only KIM-1 with near 64K RAM!

The TTY interface can be used by either the RS232 port or the USB of the MULTICOMP board.

Use any good terminal emulation as a paper tape reader/punch to save and load memory content in hex.

To the left is the not yet stuffed Audio Interface.

Circuit diagram: kim.pdf

The leftmost digit is dimly lit because “SCANDS” parks the multiplexer in Position 10 which does not exist in the original KIM-1 hardware.

Copyright (c) 2018, Reinhard Meyer
Revised 2018-05-09