Commodore CHESSmate
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(pictures copyright by M.A.Grundke)
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CHESSmate type plate (left side of the machine):
| COMMODORE INTERNATIONAL LIMITED | POWER SUPPLY:
AC ADAPTOR
MODEL C160 | POWER RATING:
AC 10V 600mA |
CHESS MATE
201490 01
MADE IN HONG KONG |
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CHESSmate warranty note (center of lower side):
CAUTION
DO NOT OPEN MACHINE
UNAUTHORIZED SERVICE
VOIDS WARRANTY. | ACHTUNG
NICHT ÖFFNEN
SERVICE OHNE AUTORIZATION
ANNULIERT DIE GARANTIE. |
ATTENTION
NE PAS OUVRIR
SERVICE PAS AUTHORISE
ANNULE LA GUARANTIE. |
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ASSY 201482 REV A board overview (lower side):
on the board's top left, you can see the MOS 6530 RIOT, with ROM (and probably option ROM soldering pads) below it. To their left, connector and cable leading to the machine's membrane keys. Further below the MOS MPS 6504 CPU, and still below, the two RAM chips. The rest of the chips are logic circuits (74LSxx-type). In the board's lower right corner, you can see
the piezo-electric speaker, with voltage regulator and heatsink to its right (and wires leading to the PSU connector at the machine's back). In general, it's quite a simple PCB design |
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ASSY 201482 REV A board overview (upper side):
here are the four 7-segment LED displays the CHESSmate uses for its internal chess clock and for showing move coordinates. Below them the four standard LEDs showing the status of the game ('CHECK', 'CHESSmate loses', 'CHESSmate is playing WHITE', 'CHESSmate is playing BLACK') |
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| The CHESSmate's keyboard PCB from below. As mentioned earlier, the foil cable (top) connects directly to the mainboard. Also visible are the four transparent plastic 'windows' for the 7-segment LEDs shown above |
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CHESSmate board silkscreening:
C= commodore
CHESSMATE
201482
REV A |
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| The MOS 6504 is a rarely used CPU. It's just a stripped down version of the popular MOS 6502, able to address only 8 KBytes RAM (the 6502 can address 64 KBytes) and missing the two IRQ-lines NMI (non-maskable interrupt request) and RDY (memory ready). It's available in 1, 2, 3 or 4 MHz-versions; I assume it's the 1 MHz version (like in most CBM 8 bit designs), because there's no additional letter in its label (in MOS-fashion, the faster versions get an additional letter to their name,
such as MOS 6502A is the 2 MHz-capable 6502) |
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| The MOS MPS 6530 'RIOT' is a multi-function chip that unites two 8 bits I/O-ports, 1 KByte ROM (1024x8), 64 Bytes RAM (64x8 static RAM) and a programmable interval timer plus timer IRQ on one IC. Again, there's no additional letter printed to it, so it must be a 1 MHz version
(but there was a MOS 6530A rated for 2 MHz as well). Note also that, according to CBMs datasheet, up to seven RIOTs can be addressed with one 650x-CPU, allowing 7 KBytes of contiguous ROM. Furthermore, the 6530-RIOT is not pin-compatible with its successor, the MOS 6532, so replacement in case of a defect could be a real problem... |
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| The CHESSmate's MOS 6332 ROM, with soldering pads for another IC before it. Since a similar ROM is also part of a BASIC 2 ROM-set in some PET-models, I assume it is 4 KBytes in size. So together with the MOS 6530's integrated ROM, the machine's got 5 KBytes ROM, most of it containing the chess-routines (i.e. Peter Jennings' MicroChess 1.5) - however, exact contents
are unknown (yet). But back to the soldering pads: should they be for a second ROM, they would be the earliest implementation of an option ROM in a CBM computer I know of (option ROMs were used for easier expandibility and flexibility in the PET-series, the Plus/4 and C128-series) |
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| These two AMD AM9111BPC 256x4 SRAMs imply that the machine has 256 Bytes static RAM. Together with the 64 Bytes of the RIOT, we've got 320 Bytes at all. But for what? Probably for storing chess moves to let them be analyzed by the CPU? |
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| The CHESSmate's onboard piezo-electric speaker. This is a cheap solution for producing noise (don't wanna call it 'sound'), and was also used in the later PETs |
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| The C160 AC adaptor, CBM part-no. 400205, made for the CHESSmate. As you can see it has a non-standard, three-pin power plug |