As a next step in trying to dump the Tamagotchi code, I’m trying to dump the mask ROM that comes in Tama-Go figures. After an hour or so of messing around with a signal analyser, I decided to take a look at the board.
On the right is an unpopulated board for that Tamagotchi figure, the blue areas are what was visible before I scraped the covering off the traces. Based on the position of the pads and the size of the rectangle for the die, I think it’s a GeneralPlus GPR26LXXX Low Voltage SPI ROM, either the 8MB or the 16MB version.
This means that the Tamagotchi figure pins are then as follows:
1, 4 and 8:
Ground/Jumper Power/Jumper (Edited 2013/02/09)
2: Serial clock (C)
3: Serial data input (D)
Power Ground (Edited 2013/02/09)
6: Chip Select (SB)
7: Serial Data Output (Q)
I tried to confirm this by removing the PCB from the back of the die and taking a peek at the pads (yes, I realize now that they’re on the top).
It turns out that this is not a recommended technique.