Micro KIM-1 Rumblings

MOS/CBM/Micro KIM-1 Rumblings


So, I was given a couple of KIM-1 computers when I was a teenager. One was produced by MOS and the newer by CBM (Commodore Business Machines). In my teenage years I learnt 6502 assembler on these things, hooked many circuits with blinken LED's and other items and generally had a ball. Looking for (yet another) sanity project I thought I'd try and see if I could describe the boards to $parent and get him to post them from the west to me here in Sydney. This proved difficult and in the process of searching for a software emulator I stumbled across Briel Computer's "MicroKIM-1" page.

Vince Briel flogs all manner of retro and repro kits (..do love yer work son!). His page for the MicroKIM-1 can be found and here.. the manual for the MicroKIM can be found here.. I really find these MicroKIM-1 replicas highly appealing because they don't use any FPGA's, CPLD's or PIC's and use exactly or "very close" versions of the original chips. The only major differences between the Briel MicroKIM-1 and the original MOS/CBM's is the RRIOT chips which are newer revisions than the originals (128bytes of RAM instead of 64bytes) and the Terminal interface being RS-232 on the modern variant instead of an ASR-33 circuit I had on the original. This is all "in keeping" with the spirit of the original machine. Some of the bus signals have been cleaned up also which isn't a bad thing either!


So. I ordered one and it arrived a few weeks later (be patient!). After a fair bit of fiddling about and soldering the kit worked. I was overjoyed and messed around with it for many weeks before deciding to get the 32KiloByte REU (RAM Expansion Unit), Second RRIOT and the expansion board. These all arrived dutifully as kits which I soldered up and they have worked. I've had weeks and weeks of fun typing in via the keypad and the serial port (at 2400bps!) programs and sitting in front of the BASIC interpreter.


Here's a log file of a terminal screen session loading the HEX code blob for the 1977 MicroSoft 9-digit precision (KB9) BASIC interpreter and running the BASIC interpreter interactively off the serial port saved as a Text file. Link! Of course, if you have a KIM you can copy & paste the HEX codes into your KIM and it should run if the load addresses are set correctly. Scroll down near the bottom if you are Gen-Y or otherwise impatient.


Photographs - Click on a thumbnail to enlarge then hit the back arrow


MicroKIM-1 examining the contents of memory at $022E ..which was Zero




Side-view looking at the second RRIOT 6532 break-out board.




All components spread out on the kitchen chopping board (Good light there of an afternoon)




Upside down Ms Jane..




Run Time side ways..




Top down view..




More top-down..




More Bill Steam-Shovel style (..I wonder how many aussies got the first one)





End of a MOS6502 odyssey. Created with EDT on said VAX under VMS 7.3-1 naturally.
03-OCT-2013 18:41