Skip to content

ROMs and other information gathered from a customized KIM-1

Notifications You must be signed in to change notification settings


Repository files navigation

BDC-6500: ROMs and other information gathered from a customized KIM-1

I purchased this customized KIM-1 computer from an estate sale, and have since been documenting it and trying to get it working again.

In the handmade enclosure, I found a Rev D KIM-1, a 16K memory board, an 8K "Visable memory" board, and finally a hand-wired ROM board. The 4 1k ROMs were labelled KVOS.

The only documentation I've found of KVOS is a single ad announcing its availability as a 6502 OS available from CGRS Microtech, in the December 1978 issue of Popular Electronics:

I was able to dump the ROMs with a handmade board (see though the dumps seem to be corrupted in places. I'm not sure yet if it's the ROMs themselves or the reader.

update: The latest dumps from my rebuilt reader are cleaner and more consistent. Any weirdness that remains is likely in the ROM itself, and not a result of a bad read.

This repo is to document the disassembly of the ROMs and other findings as I get deeper into rehabbing the original BDC-6500.


I'm using da65 with the info.txt file in the main directory. Since the ROMs seem to be corrupted, I've made some modifications to the complete dump, in the file F000-FFFF-combined-modified.rom. The original dump can be found, unmodified, as well. As I update my reader, I will replace the dumps, if they end up being cleaner.


Photos of the enclosure, boards and wiring here:

Character ROM

I've recreated the KVOS font from the character section of the ROM. Bitmaps of the full ASCII set are in the "Character ROM" directory.

KansasFest 2017

A quick presentation on my findings and the background on KVOS, presented at KansasFest 2017, is available here:


ROMs and other information gathered from a customized KIM-1






No releases published


No packages published