25 Jan 2017

World Rally -Gaelco 1993 (repair log)

 The game booted but had 2 issues:
- RAM checksum error at address XXX (changes every time you power the board)
- Coprocessor not ready (indicates the game has committed suicide)

For the RAM error I first thought it was bad but discovered a cut trace. I patched it and the problem was fixed.

Then I tried to un-suicide the game. I first replaced the battery. Then I needed a RS232 to TTL converter and as my computer doesn't have a serial port anymore (I had it through the docking station but I got rid of it...) I went the USB to TTL converter route:

The pinout on the World Rally board is as follow:
- 1 (closest to the printed 0) = VCC
- 2 = TXD
- 3 = RXD
- 4 = /PROG
- 5 = GND
You must bridge /PROG to GND on the board and connect only 3 wires to the TTL adapter (GND/TXD/RXD). Pinout may vary according to the adapter so just check yours.
The port settings are 2400b/s, 8 data bits, no parity, 1 stop bit and XON/XOFF flux control.
With hyperterminal (or any other serial communication software) send a carrier return. The game should answer "DS5002 LOADER VERSION 0.1..."
Then send U, the game should answer "UNLOCKED".
Send L, the game waits for a file to load.
Copy and paste the following code:

Gaelco wrote:File too big

Can be found here:
(Or you can do as I did: download the romset on Gaelco website and convert the wrdallas.bin file to hex).

Transfer is quite long (between 5 and 10mn?).
When finished type Z to lock the DS5002.

Unfortunately it didn't work for me on first try. The cause was another broken trace. I fixed it and started the download procedure again and it worked!
Another game saved.

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