KIM-1 Revisions, what changed?

I know of seven KIM-1 revisions, labeled Rev A-G and the first one unlabeled. Rev C is unknown!

What changed between these revisions?

Not much. The PCB underwent several changes around the logo area, from KIM-1 MOS to Commodore C-MOS. That happened from Rev A to Rev D, indicating the takeover by Commodore of MOS Technology. And some small numbers/artefacts etched in various Revs.

Some have serial numbers, the first ones on the back on the right, later had stamped/written numbers like PAxxx (Palo Alto) and SCxxx (Santa Clara) of Commodore production facilities

There was a real change in the PCB from Rev A to B.

Rev A

Rev B

The User Manual went from version 15 (January 1976) to 15A (March 1976) to 15B (August 1976) without significant changes, mostly typing errors and the change of keyboard from Rev B to Rev D.
The keyboard changed from rev B to Rev D. The SST switch moved to the other side, the first Rev keyboards were not very reliable.

Rev B

Rev D

What did not change?

The 6530 – 002 and -003 were from many different dates between 1976 and 1980. The functionality stayed the same, no software changes are known. It seems the same mask was used to produce another batch due to the demand for KIM-1s. On Rev F and G I have seen older 6530s (ceramic ones) from much earlies dates, old stock being used?

The large Circuit Diagram poster stayed the same for all revisions.

Parts used

The parts used in all these revisions changed from as much as possible made by MOS Technology (6102) to industry standard compatible types (2102). E.g the RAM ICs were all third party in later revisions.
The capacitors, mostly yellow tube types, also came in various colors and sources between revisions.

Except for Rev G no IC sockets were used.

KIM-1, were IC sockets used?

Before I saw the last revision, Rev G, I had never seen an original KIM-1 with IC sockets. All ICs were soldered right into the PCB.

Now I have a KIM-1 Rev G and a photo by Dick Dral of his KIM-1 Rev G with white IC sockets.


So the last iteration of the KIM-1 did have IC sockets.

Not only did Rev G come with sockets, they used not only white sockets, black ones too (Thanks Santo Nucifora).

Images of the 6530s I have

Over the years I have acquired quite some 6530 ICs. Either as IC or built into a KIM-1, Jolt or Chessmate.

On this page I show these 6530s.

My KIM-1 collection

In 2024/2025 I completed my KIM-1 collection with one or two from every Revision, from first edition to Rev G, nine in total.

Versions of the KIM-1 User Manual

I have so far found 5 versions of the KIM-1 User Manual.

First Edition January 1976
Second Edition March 1976
Second Edition August 1976
Rockwell branded version 1977.
German version 1977
Only small updates, some errors, and the change of keyboard with SST switch right to left.

All available here: KIM-1 manuals and MOS Technology documents – Retro Computing

The Rockwell KIM-1, myth or?

Was there a Rockwell KIM-1? A myth or? Yes and no.

There is a KIM-1 packaged and sold by Rockwell in 1977. I bought one in 1977.
No, it is a MOS Technology produced KIM-1 PCB.

Yes, Rockwell added documents with Rockwell title pages and contents 99% written by MOS Technology.
The Rockwell KIM-1 is just an OEM product!

The Rockwell KIM-1

Once in a while I hear a myth on the internet about Rockwell manufactured the KIM-1. That myth needs to be debunked.

Rockwell did sell KIM-1s as an OEM product around 1977. They bought the KIM-1 PCB, made in a Commodore factory and put a sticker on the right corner, covering the Commodore MOS logo and text, as you can see in the image below.

The documentation such as KIM-1 User Manual and the Circuit Poster were given a new front and back, the contents of the User Manual were 99% coming verbatim from MOS Technology/Commodore. The Programming and Hardware Manual were later (and better) versions of the MOS Technology documents, no trace of the 6501!

I can proof this, in 1978 I bought a KIM-1 from a Dutch distributor Famatra and still have it. It was a Rockwell package. Here you see photos of my Rockwell KIM-1 package labeled as Rockwell but it really is a Commodore MOS Technology product rebranded. It did not take long before Rockwell started to sell the AIM 65 as replacement and I never saw advertisements not a Databook with a Rockwell KIM-1 in it.

The Rockwell KIM-1 User Manual is scanned by me and available on the KIM-1 and MOS Technology manuals page, as are (later versions of) the Rockwell Hardware and Programming manual. I might scan these Rev 0 versions one day also.

See the page of me and my KIM-1 for my first KIM-1 and its history.

You can see the text Commodore and MOS logo shining trough underneath the Rockwell sticker. And the number SC1276 gives away it was manufactured in the Santa Clara Commdore factory.

MCS6500 Family Hardware manual 6500-10 and Programming Manual Synertek 6500-50 added

New good quality scans added to the Manuals page
– MCS6500 Hardware Manual August 1975 First Edition, Version 6500-10, with errata letter. Not the usual 6500-10A but the rare first edition. No ROR instruction documented!
– MCS6500 Programming Manual by Synertek, version 6500-50. Not the First Edition alas, the contents are the 6500-50A version.

I now have two first edition MOS Technology manuals:
– MCS6500 Hardware Manual August 1975 First Edition, Version 6500-10
– KIM-1 User Manual First Edition, January 1976, no version but could be 6500-15. The newer versions are version 6500-15B

Still missing, but it does exist somewhere, is
– MCS6500 Family Programming Manual, 6500-50. All scans, including mine, are version 6500-50B.

This is the title page of MCS6500 Family Programming Manual, 6500-50, of which no scan is knwon yet.

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KIM-1 connectors: beware the Chinese cheap variants!

The KIM-1 needs 2 edge connectors.

The specifications are: card edge; PIN: 44; 3.96mm

When you search for those, the cheap ones pop up, Chinese made, look good. But they are no good, when you slide them one you need a lot of force, some even use a hammer!
The PCB is too thick for these connectors, you damage the edge fingers and can not change once connected.
DO NOT USE THEM for a KIM-1!

I had some luck, years ago I bough a lot, cable type (solder eyelets) from Conrad and they are perfect for the KIM-1.

307-044-500-202 Standard Card Edge Connectors 44P SOLDER EYELETS 5.08mm ROW SPACE, for sliding on a PCB edge connector.
307-044-520-202 Standard Card Edge Connectors 44P Card Edge PC Tail, for a motherboard

EDAC 307 357 Series Card Edge Connectors English Ordering Guide

307-044-520-202 – EDAC Card Edge Connector

307-044-500-202 – EDAC Card Edge Connector

Microsoft’s 6502 BASIC is now Open Source

Microsoft’s 6502 BASIC is now Open Source, and that includes KB9 or as it is officially called:

MOS TECH 6502 BASIC V1.1
COPYRIGHT 1977 BY MICROSOFT

Microsoft’s 6502 BASIC is now Open Source

“Now, for the first time, this influential 6502 version is truly yours to explore, modify, and share.”

This means that we are allowed to distribute and modify KB9 and derivates without breaking licenses!

Also see the pagetable post from 2005 that explains a lot about this source.

The Easter Egg in KB9:

Answer ‘A’ to the Memory Size Qustion and see this:


Now we all know about Bill Gates. Ric Weiland is less known. Second Micro-Soft employee. Left 1988, and became a philanthropist, see Wikipedia.

The license that goes with 6502 BASIC is now:

MIT License

Copyright (c) Microsoft Corporation.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the “Software”), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE