The Final Chesscard by TASC was released in 1989 for the Commodore 64/128 and PC. The C64/C128 version plugs into the Expansion(cartridge) slot and the PC version comes with an ISA Card.

The Chesscard forms a stand-alone computer with 32K of ROM, 8K of RAM and an extra CPU running at 5 Mhz. Program software was delivered on disk for the PC and the C64 software is loaded from an additional 32K ROM on the C64/128 cartridge.

 

The Final Chesscard C64/C128

Unfortunately my Chesscard only displayed a black screen with white stripes, so I began to investigate it.

The C64/C128 Chesscard has two 32K ROMs which I dumped with an eprom reader. One ROM with software for the external CPU and the other has software for the C64. This also revealed my Chesscard was in the german language.

The C64-ROM consists of two banks, both 16K at $8000-$bfff. The bank is selected by setting $DE00 to $40 or $41. The Chess-ROM is 32K at $8000-$ffff and boots independently with reset vectors pointing to $FF22.

I needed a way to test the ROMs. The same company was involved in making the “Final Cartridge III” which has 16K sized banks and uses $DE00 for bank swapping. I created a TFC3-type cartridge ROM for emulators(.crt) and wedged in code to set $DE00 accordingly. The Final Chesscard now started up in the Vice emulator, displaying a black screen with white stripes.

Now it became much easier to debug. After examining the code, I could see the “black screen with stripes” was waiting for the extra CPU to acknowledge it was running (possibly these two communicate with each other using zeropages $04-$0e). I removed the checks and had the Chesscard running graphically, the chess engine itself was of course not working.


The Final Chesscard in Vice (Working partially without the extra hardware support)

 

I eventually figured out the extra CPU did not start up properly. I took out my desolder gun and removed the CPU. It was tested OK on another equipment. After desoldering the crystal I noticed that one of the legs was broken, and while at it, I decided to clean up the whole PCB for documentation purposes. You will find scans and pictures of the PCB below.

 

Component list:
74LS04
74LS30
74LS32 x 2
74LS74
74LS174
74LS374 x 2
SRAM = 8Kx8 TC5565/MCM6064
CPU = G65SC02P-4
ROM1/ROM2 = 27256 Eprom
D1-D6 = Diode 1N4148
ZD1 = Zener diode 2V7
C1-C2 = Tantalum 1uF 35V
C3-C6 = Ceramic 0.1uF
C7-C9 = Ceramic 1.0nF
C10 = Ceramic 0.56nF
X1 = Crystal 5Mhz
Resistor 2.2 KOhm x2
Resistor 680 Ohm x2
Resistor 330 Ohm
Reset button

 

Everything back in place and all IC:s socketed.
 


Final mount. The Final Chesscard is now fully functional with english language.

 
ROM Downloads:
There are two language options for the Chesscard; english and german. The language is hardcoded on the ROM. The english ROM has been quite hard to get hold of(until now). There are demo-versions out of both, which are easy to find, but they are not compatible with the ROM version.

With information from studying the code, I managed to make a C64 tool to extract the ROM and thanks to Ratuv at Lemon64, who kindly run the tool on his english Chesscard, there is now an english ROM available for download.