There are at least seven KIM-1 board revisions, labeled A through G (plus the original unlabeled one). Rev C is a mystery - nobody's confirmed one exists. If you have one, the retro computing world would like a word.
retro.hansotten.nl/kim-1-what-changed-in-the-revisions/
MTU K-1013 FDC emulation added to the KIM-1 Simulator.
Eduardo Casino added the FDC support. Now not only the SD Shield but also the upd765 based FDC support allows to run CP/M-65 and the native CODOS for KIM-1 operating systems.
retro.hansotten.nl/6502-sbc/kim...
This is what a maxed out KIM-1 looked like:
R65 - A late seventies computer built with a KIM-1
github.com/rricharz/R65...
#65o2 #mos6502 #kim1
Martin Reiser's law (Wirth's law) is still valid: Software is getting slower more rapidly than hardware is becoming faster, 1987!
Wanted a case for a KIM-1? Options in the 80ties were available. Here an example, suitable for educational purposes.
But reading a tape from another user was always a time consuming challenge. Even tapes bought with Microsoft Basic KB9 or Microchess and MICRO ADE took several hours to get it right.
It required careful tuning the PLL, the tape azimuth head of cassette recorder and a tuned amplifier (volume and pitch). Combined with Hypertape and good two motor controlleed cassette decks it was very reliable.
I met him in Utrecht at a university lecture with Niklaus Wirth and Edsger Dijkstra. A very special moment!
Also on my website, this post triggered me to document the issue today.
What changed in the KIM-1 Revisions?
The PCB underwent several changes around the logo area, takeover by Commodore . The big change was in the clock circuit between the first edition and Rev A.
The first batch of KIM-1 suffered from the issue that the clock would not start. It was fixed in Rev A.
Runs on the KIM-1 Simulator under KB9V2!
Best of MICRO here: retro.hansotten.nl/6502-sbc/kim...
and the whole archive here: micro.applearchives.com
Wozmon, the Apple 1 monitor, his first 6502 code, is genius
New versions of KIM-1 Simulator (V2.0.0) with SD Card Shield, CP/M-65 and xKIM, and Jolt Simulator (V0.9).
Read all about it here: retro.hansotten.nl/new-versions...
Eduardo Casino has created a faithful replica of the Jolt single board computer.
6502,6530-004 TIM and 6520. TTY or RS232C 512b RAM.
He designed using the information available.
The replica on GitHub, github.com/eduardocasin...
More information on the Jolt, retro.hansotten.nl/6502-sbc/jol...
White KIM-1 cleanup
This one is a Rev D with a ‘white’ PCB. The KIM-1 is working.
The keyboard handmade@.
With the DIY keypad method based upon the work of Eduardo Casino and Pete (peo2000)I replaced the keyboard
Wires removed clean with alcohol and a brush this KIM-1 may join my collection
A spare KIM-1 keypad is even rarer than a KIM-1 itself. With this guide you can build a reasonable replica of the keypad.
Thanks to the work of Eduardo Casino (the PCB) and Pete (peo2000 on forum64.org) I have published a DIY guide for a KIM-1 keypad replica.
retro.hansotten.nl/6502-sbc/kim...
The A-ONE family on my desk
Well, not entirely new. Developed in 2006, I have one since.
New production started last year, same design. Excellent product. The PLUS is new, nice package with mini PS/2 keyboard.
In 2025 Franz Achatz revived the A-ONE Apple 1 replica. The excellent design is refreshed, a new family member added: the A-ONE PLUS.
I now have the 2025 standard board, the 2025 PLUS and the 2006 EXTENDED. With the prototype boards and cassette interface. retro.hansotten.nl/6502-sbc/app...
It is a good product with excellent documentation. Circuit diagram, firmware, all available.
Apple 1 show off
The first time I saw 6502 self modifying code is in the KIM-1 monitor. The VEB logic modifies the loading or storing instruction for save or load.
Sir Charles Antony Richard Hoare (11 January 1934 – 5 March 2026), also known as C. A. R. Hoare, pioneering computer scientist.
His seminal contributions include -
Quicksort
Quickselect
Hoare logic
Null reference
Communicating sequential processes
Structured programming
ALGOL
Yes, I remember very well. The first PET 2001 that was imported in the Netherlands. I was having one for a review for a magazine several weeks. My first review of a home computer!
Amazed at the power and functionality and the horrible keyboard!
