John Bell Engineering

The page on John Bell Engineering has been expanded to a page per SBC, to keep the information accessible. See it here.

Glen Deas supplied negatives of 80-153 and the Z80 cards, thanks!

I also added the information I have on Apple ][ cards by John Bell, like the 6522 VIA and A/D cards.

My retro toolchain

Development for my old 8 bit retro SBC’s has become much easier with fast PCs and good tools. All cross development.

What took hours on my KIM-1: load editor form tape -edit source – save on tape (multiple tape files if big) – assemble form tape to tape – load binary from tape – run
can now be done very fast.
Powerful text editors, cross assembler, KIM-1 Simulator, seconds per iteration.

The only slow part remains: me!

More on my favorite toolchain here.

PRDIS, Printing Disassembler

In 1982 I wrote/composed a program to have disassembled code on paper, with page numbers. Read more about it here.

The core routine of the disassembler is the well-known Steve Wozniak/Allen Baum 1976 article A 6502 Disassembler from Apple
The program is a TTY program. I build it with the then current hardware and software of my KIM-1:

  • 32K RAM from $2000
  • Video terminal uppercase 24×32 on the KIM TTY serial in/output
  • A parallel ASCII keyboard connected to the second 6532 RIOT port
  • A serial connected, at 9600 baud, Heathkit H14 matrix printer
  • Dual audio cassette records under motor control
  • MICRO ADE assembler/Editor, extended and with video TTY as output, parallel keyboard as input and could print at the H14 printer

Corsham Bus Extender

Corsham Technologies produces a Bus Extender fot the KIM-1. Simple but so handy

It is placed beween the external device on Application or Extension Connector and has 44 pin header to attach wires to a breadboard for example.
Only negative I can say about it, tinned edge connectors and not gold plated.

Nice addition to my Reproduction KIM-1s!

MOS KIM-1 Reproduction, white version

Dave Wiliams made a revison of the MOS KIM-1 Reproduction, a white version.

The original green and the new white are for sale at ebay as of January 2023.

More information here.

AIM 65 clone

Mr. Nagano, from Tokyo, Japan send me photos and circuit diagram of an AIM 65 clone he built. It is a beautiful and functionally and esthetic faithful clone. In fact, he built two, one with a CPLD 3V3 version and a 5 V version with a 6532 RIOT.

Read all about it here.

6507 breadboard computer

A 6507 CPU with a 6532 RIOT and a 27C512 EEPROM on a small breadboard.

Github with circuit diagram and sources

KIM-1 Rockwell sticker

My KIM-1 came as an Rockwell OEM kit. The Rev F board is made by Commodore MOS Technology, the packaging and manuals are the original MOS Technology books, but Rockwell branded.

The logo on the KIM-1 is covered with a sticker, of course to have the Rockwell logo on the board. But some one was so clever to add essential information and addresses of the KIM-1 monitor.

KIM-1 Rev A Photos

Guido Lehwalder gave me photos of his KIM-1 Rev A. Thanks!
Note the different colors of components.

I added these to the KIM-1 Revisions page.

Rev A, photo by Guido Lehwalder


Rev A, photo by Guido Lehwalder

Tor-Eirik Bakke Lunde a.k.a TEBL created several computer systems with detailed documentation.

The RC-ONE is a KIM-1 clone, inspired by the design by Ruud Baltissen, which can be built in a compact to much expanded format.

TEBL separated functionality into separate boards so that each version would cost only around 5$ per piece instead. It means it’s no longer a single board computer, but if it means more people can build it as a fun project then that’s a plus in my book. The main setup does not include the additional 15 I/O lines due to space requirements, but you can add those back to the system by including the 65K Expansion (in addition to the backplane module) if you want to. If you just want to play around with the system and try your hand at machine language coding, you can get started with the CPU board, UI board and a keypad module.

The whole design is documented on TEBLs github page, from circuit diagrams to PCB design.

The manual is an excellent guide to the system, read that first!