The Micro-KIM is a SBC designed and built by Vince Briel. First sold in 2007 and alas not available anymore.
Based upon the ideas of Ruud Baltissen how to replace the 6530 with a 6532, it was the first KIM-1 clone that was running the unmodified KIM-1 ROM.

Manuals, circuit diagrams, single step fix, tape devices, support Cd images


  • 6502 CPU running at 1Mhz
  • 2K EPROM replacing built in ROM on 6530s
  • 5K RAM using the KIM-1 memory map
  • RS232 interface made to work with TIM built in KIM-1
  • Single-Step mode for debugging
  • debounced RESET and STEP switches
  • 40 pin header for future expansion
  • Expansion board for expansion connector with four slots available
  • 32K RAM card
  • Second 6532 board
  • The I/O of the 6 digit display and keyboard are memory mapped exactly like the KIM-1 for full program compatibility

See the KIM-1 page for more KIM-1 info and programs.

First impressions

  • It really feels like a KIM-1. Smaller, but just as simple to operate. Easy to connect a serial RS232 (USB) cable and connect to a terminal program. Minicom on Linux, Realterm on Windows e.g., no high demands on terminal emulation, just plain simple teletype at 9600 baud or less and the ability to capture output to a textfile or send a text file via the terminal
  • No cassette port. This means the programs with real nostalgic value like the editor/assembler Micro Ade will not have much sense.
  • Second 6532 is an option(though the 6530-002 and 003 ROM is present!).
  • 32K RAM extension option. Yes, this makes the machine worthwhile! Now you can run KB9 Microsoft Basic or otehr KIM-1 software.
  • Some small mistakes are on the version 1 Rev 0 board, fixed in the later version rev 1, this needs three hardware fixes to be made, so I have to get the soldering iron into action. Simple fixes, see below.
  • Loading programs via the serial interface by sending a text file in papertape format is slow. But it works! Fun to test all those KIM-1 programs. KIMTAPE and KIMPAPER help a lot here also look at the 8 bit hex file conversion program there.

Tested programs

Most of the First Book of KIM programs work. Some require the presence of the second 6530 (6532 here).
See the KIM-1 software and manual pages. Also see the photos section for TinyBasic and KB 9 Basic.

See the KIM PC utilities page for papertape and other conversion utilities.

Memory map

Micro-KIM KIM-1
$0000-$03FF 1024 Bytes of RAM $0000-$03FF 1024 Bytes of RAM
$0400-$07FF 1024 Bytes of RAM $0400-$07FF Optional Memory Area
$0800-$0BFF 1024 Bytes of RAM $0800-$0BFF Optional Memory Area
$0C00-$0FFF 1024 Bytes of RAM $0C00-$0CFF Optional Memory Area
$1000-$13FF 1024 Bytes of RAM $1000-$13FF Optional Memory Area
$1400-$16FF Optional Memory Area $1400-$16FF Optional Memory Area
$1700-$173F Optional 2nd 6532 I/O, Timer $1700-$173F 6530-002 I/O, Timer
$1740-$177F 6532 I/O and Timer $1740-$177F 6530-003 I/O, Timer
$1780-$17BF 64 Bytes RAM from 6532 $1780-$17BF 64 Bytes from 6530-003
$17C0-$17FF 64 Bytes RAM from 6532 * $17C0-$17FF 64 Bytes from 6530-002
$1800-$1BFF 1024 Bytes of EPROM $1800-$1BFF 1024 Bytes of ROM in 6530-003
$1C00-$1FFF 1024 Bytes of EPROM $1C00-$1FFF 1024 Bytes of ROM in 6530-002
$2000-$FFFF Unused memory $2000-$FFFF Unused memory or 32K RAM baord

* The 6532 has 128 bytes of RAM vs. only 64 bytes on the 6530. The Micro-KIM utilizes all 128 bytes from
the single onboard 6532 so all original memory locations are available.

Manuals, circuit diagrams, notes and support Cd images

Micro-KIM setup and Users Manual July 2007 Rev 0 Ed 1
Micro-KIM setup and Users Manual September 2007 Rev 1 Ed 2
Circuit diagram Micro-KIM rev 0, has serious errors
Circuit diagram Micro-KIM Rev 1
Support Cd contents Rev 0 July 2007
Support Cd contents Rev 1 September 2007
Fix for Micro-KIM Rev 0 for second 6532
Aart Bik’s programming the Micro-KIM, see also his KIM page

Extensions and audio interface solutions

65C02 Single step fix by Timali

My Micro-KIM shipped with a 65C02, and apparently there is a timing issue which prevents single-step from working with the 65C02. I tried an original NMOS 6502, and single-step worked ok with it, but not with any of my 65C02s. I did some debugging with my scope and determined that there is a small timing difference causing the SST signal to be erroneously asserted (pulled low) for 100-200 ns during EEPROM accesses with the 65C02, which is just enough to cause a problem. The easiest way I could think of to fix this was to delay the SYNC signal briefly with a small RC circuit, which prevents the glitch in the SST signal. I cut a trace on the back side of the board and added a small resistor and capacitor, and single-step is now working correctly with my 65C02’s. It still works with the original 6502, also. Click on the image to see a larger picture.


Tiny Basic

Microsoft Basic KB9



KIM 6530 replacement

Have a KIM-1 with faulty 6530? Look here for replacement with 6532 and some.


KIM-1 6530 Replacement

Text, copyright and product by Corsham Technologies

If you don’t want to build your own version from schematics, Corsham Tech does offer three options:

  • Bare Board
  • Kit
  • Assembled

The bare board is just the board.  Documentation is on this page.  It’s mailed in a small envelope and can be built with commonly available part

Like many people, I (Bob, Corsham Tech) have a KIM-1 in my collection with a dead 6530 chip.  Fortunately mine wasn’t too bad, but one of the I/O pins didn’t work so the display always had one segment lit and the TTY port would not work.  After many hours of searching for a way to replace this one defective chip with an equivalent circuit, it became apparent a lot of people were trying to do the same thing, some claiming to have a solution, some not, but no schematics ever appeared.  Without schematics, there is no solution.

Rather than letting others go through all the effort to reverse engineer the 6530, I decided to make my own, and to publish the schematic.  This work was heavily taken from Ruud’s excellent tutorial on his efforts to replace a 6530 in a Commodore disk drive.  Please go to his page for an explanation:

http://www.baltissen.org/newhtm/6530repl.htm or see the 6530 pages here.

Since the 6530-002 and 6530-003 in the KIM have different mapping of ports, his exact schematic is not right for the KIM, so I borrowed some of his KIM-1 clone ideas and designed my board from it.


  • No, the schematic is not pretty.  I can spend some time and shuffle parts around to make the parts placement neater, but if you’re contemplating building this, I’m sure you’ll have no problems following the schematic.
  • Pin usage has not been optimized.  This was breadboarded but the PC board design is not done so some of the pins on the 74LS00 might change.
  • There are three jumpers with U2 and 003.  The intent was to be able to replace either of the two 6530s on the KIM and both U2 and U3 have been tested.
  • A 28C64 EPROM was chosen because (A) they’re readily available, (B) common USB programmers can program them, and (C) the offset in an Intel HEX file for the KIM PROMs will be at the proper offset when you load the files into your programmer’s memory.  Ie, the 002 device’s offset at 1C00 will be at offset 1C00 in the EEPROM.


PDF version of the manual.

EEPROM Contents

The basic KIM has an 8K memory map so using an 8K EPROM/EEPROM makes things easier because the address in the HEX file is exactly the right offset into the EPROM.  If you don’t understand this, don’t worry, you don’t need to.

I deleted the two individual hex files and replaced it with a single file that covers both halves of the KIM PROM:


The image is a raw dump from a working KIM, not re-assembled from source.  Note that I had to add an extension of txt so that WordPress would allow me to upload them, but take off that extension when you save them to your computer.

Design Files

Bare boards are available, but these are the files you can use to generate your own. First, this is the GERBER file from the revision 1 boards I sent to have boards produced. If you want to make your own boards without any modifications then just upload this file to your favorite PC board manufacturer and they can give you a quote:


If you use the EAGLE CAD package, here are the files needed for the project. This has the epf, brd and sch files:


BTW, this is what the top layer of the board looks like, minus any traces:

Just like Ruud’s original design, this has the 6530 header and 6532 socket overlapping each other. For the header that is soldered to the underside of the PC board and plugs into the KIM, I suggest a header with narrow pins. I used CNC Tech part number 220-1-40-006, available from Digikey as part number 1175-1527-5-ND. Be aware that the cross-pieces of the IC socket and the header will block the pins for the other, so you’ll need to cut them from either the socket or the header (whichever you solder last).

VERY IMPORTANT: Notice that IC3 and IC5 are polarized exactly opposite from the others! When you insert sockets and chips, double-check you’ve got them oriented in the right direction!

Prototype in action!

Replacement board in U3 location, works!


DOS65 information now complete

The DOS65 information is now complete. Last year I did document most of the system. And now I scanned the large pile of paper with manuals and source listings that were waiting to be added. Source listings of ROM, the Operating system and the Monitor and other documents. Most are in English! Enjoy!


6502 manuals in html format

I have added the excellent html formatted manuals by Erik van den Broek to the KIM-1 Manuals page.

6502 illegal opcodes list

Groepaz from the VICE emulator team and the C64 demo group Hitmen just released an updated PDF of 6502 illegal or perhaps more accurately called unintentional opcodes.

I would say this document and the use of illegals are for advanced programmers but they can come in very handy for generating smaller or faster code at times.

Some illegal opcodes can be unstable on certain chips

NMOS 6510 Unintended Opcodes no more secrets (v0.91 – 24/12/16)

SB-Assembler 3 released

San Bergmans has released SB-Assembler 3

Download here.

Now written in Python 3, runs on Windows, Linux, Max OS.

New Features Of The SB-Assembler 3

  • Will now run on Linux, MAC and Windows machines.
  • Written in Python3, a modern multi-platform programming language.
  • Source files will be included, allowing you to create your own cross overlays.
  • Local labels from other global labels can now be accessed.
  • Can now generate warning messages where errors would be inappropriate.
  • Include source files can now be nested as deep as you like.
  • Separate target spaces for code memory, RAM memory and EEPROM memory.
  • The .TA directive can be used to map generated code to the ROM address map easily.
  • More room, we can now use Giga bytes, in stead of some 550k bytes to do the job.
  • As from Version 3.01 label and macro names may also start with an underscore.

Read More


R65C24, new in my collection

On its way from China, the R65C24. A dropin for a PIA, with a timer.

Part of the IC collection!


Lee Davison’s website

On this page I have tried to reconstruct the website of Lee Davison, the last version was on mycorner.no-ip.org.
This reconstruction and interpretation is based upon my last capture of January 2009.
EHBASIC versions are the latest, as they were saved in multiple locations on the web.
Layout and adaptions/corrections/enhancements are mine, to keep it relevant and inline with intentions of this website.

This version contains only the 6502 pages.

Enjoy and remember a gifted and nice person, Lee Davison!

6502 based projects.

By Lee Davison.




6502 Microcontrollers

Project examples

During many years I have communicated with Lee Davison, an engineer from Wales. Known for EHBASIC (6502 and 68000 version) and a wide interest in 6502 hardware and software.

Lee passed away at age 49, 27th of September 2013. These are the messages on the internet about him:

At http://www.bmdsonline.co.uk/north-wales-weekly-news/obituary/davison-lee-on/31656412 :
DAVISON – LEE. On the 27th September 2013 Lee passed away peacefully at home in Ludlow, at the age of 49. He leaves a loving daughter Zoe, parents Edna and Ian, also brothers Colin and Roger. There will be a cremation at 11 o’clock, 17th October at Mochdre. Family flowers only but donations in lieu will be given to the MS Society.

At BBCeng.info  Recollections of BBC engineering from 1922 to 1997 :
27 Sep 2013 Lee Davison, a transmitter engineer who worked at Woofferton. Dave Porter noted that “If we ever needed a digital/logic circuit he was the font of all such knowledge”.

His website was quite impressive. But alas lost. Over the years I did download some contents, in 2007 and 2009 I made a complete dump. Of course many items entered after 2009 are now lost,  archive.org shows the pages but not the images and files.

Lee Davison

During many years I have communicated with Lee Davison, an engineer from Wales. Known for EHBASIC (6502 and 6800 version) and a wide interest in 6502 hardware and software.

On this page I have tried to reconstruct his website. As said, incomplete with regards to the 2013 version, sorry about that.  EHBASIC versions are the latest, as they were saved in multiple locations on the web and I have collected diverse sources.

Enjoy and remember an special gifted person, Lee Davison!

Read More