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So now for some pictures. The prototype version looks rather like an industrial device than like a chess computer, but at least, I could get the parts.

If you want to write about the CT800, you can freely use the pictures below. However, hotlinking is disabled, so please host them on your own webspace.

In operation

the CT800 from the side with a game ongoing

This is the CT800 from the lower left corner. It is 21.5 cm wide, 13.0 cm deep, and 8.2 cm high.

the CT800 from the top with a game ongoing

Here you can see the front panel of the CT800 with a game going on. White started out with e4, and the CT800 answered g6. The little ‘b’ denotes that the move was taken from the opening book.


inside the CT800

This is an inside view of the CT800:

  • The red board at the left is the Olimex H405 mainboard, sitting on the mainboard socket. The connector with the grey flat ribbon cable is the JTAG port.
  • The beige board in the middle is the auxiliary board.
  • The switch above it is the power switch for changing between battery and external power.
  • To the right of the auxiliary board, that is the battery holder.
  • To the right of the battery holder, there is a ferrite bead that takes the external power line.
  • Above the ferrite bead, there is the beeper.
  • To the left of the beeper, that is the external power plug.


the auxiliary board from the top

The auxiliary board is the central “glue” of the system, at a size of 6 cm × 8 cm. It interfaces the mainboard, keypad, LEDs and power sources:

  • At the left bottom, you can see the fuses, two operational ones and one reserve fuse holder.
  • At the left top, there is the supercap for bridging power outages and battery change.
  • To the right of the supercap, there are the overvoltage protection diodes.
  • In the middle bottom, the voltage regulator.
  • The big socket is for the display, the smaller one for the keypad and the LEDs.
  • The transistor at the right top is for controlling the display backlight.
the auxiliary board from the bottom

And this is the bottom view. I have taken care not to build up loops for the ground line as to avoid inductively coupled disturbances. The interface cables for the mainboard and the power sources are not yet fitted. This way, taking the pictures was easier.

Mainboard socket

the socket for CPU mainboard

The mainboard fits these two 26 pin sockets. This way, I can exchange the mainboard if it should be damaged, which might happen during prototyping work.

Each wire has a label telling its function. This is helpful during assembly. Also, the colours have a meaning: red is supply voltage, black is ground, yellow is signalling, green is the keyboard, and blue is the display.

Front panel

the front panel from the inside

This is the backside of the front panel. The keys for the keyboard are at the left, and in the lower left corner, there is the little matrix board that interconnects the keys as a matrix keypad. The light key is a dedicated one. In the upper right corner, you can see the display. Below that, there are the two LEDs.


the CT800 from the back

Here is the rear view of the CT800. To the left, there is the input for the external power supply under the sealing, a USB type B socket. In the middle, the main switch for selecting the power source, external or internal. To the right, that is the CPU port used for flashing software onto the device.

The adaptor to the left is the actual programming adaptor, attached via USB. The one to the right interfaces the JTAG-port of the programming adaptor to the SUBD-15 socket behind the CPU port cover.

Carrying case

the carrying case with the CT800 inside

Finally, the CT800 has its own “mobile home”, an aluminium case measuring 39 cm × 32 cm × 16 cm. Besides the CT800 itself, it also houses the wall power adaptor, an extension cord, the programming adaptor, and some spare batteries.