I found a VTech toy laptop in a junk shop and pulled it apart to see what made it go.
What makes it go is a blob processor wired up to a 8-pin SPI flash. After removing the flash and dumping it, I discovered that the blob implements a 65c02 CPU with memory-mapped SPI memory. I track down enough of the boot process to make my own ROMs and by using a signal analyser to watch the SPI memory access I can determine that my program ('BRA $') is actually running. I've successfully managed to dump part of the internal ROM, which contains all the fun stuff for managing SPI ROM banks and I/O; I just need to figure out what it's all doing now.
I don't actually know this is a GeneralPlus device but it seems a plausible guess. They have a wide variety of products on their web site which almost match this one --- LCD dot matrix controller, polyphonic audio, ADPCM decode, etc. Unfortunately their datasheets are terrible and contain very little actual information. The best info I've found is from a Tamagotchi hacking project from about 2010 based on a GPLB5x, but this device seems different (memory map doesn't match the one in their device).
Does anyone know of any sources that have been collecting info on these chips? Even something that's nearly but not quite the same as mine will be useful, assuming similarity between devices.
Thanks!