Lee Davison 6502 website page

Lee Davison

Lee Davison’s website


The Computerist

The Computerist


PBC for the UK101 project by Grant Searle.


OSI 300 page restored

Somehow during the migration I managed to loose the OSI Model 300 trainer page.

Restored and with some additions!



KIM 6530 replacement

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


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!

Forum is no more

For many years this site had a forum. It was PHPBB based, an older version.

Not much traffic, mostly news from me (which is now also here) and some posts already added to the pages of the site.

Thank you for the contributions and the Contact page is always available for your questions and contributions!


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