I've looked at this and got a draft design in my head. The only problem I can think of is how you force a reboot of the Lynx in order to boot from the selected cart. Ie. my design is to have a 'selection' rom that interfaces the lynx to a microcontroller, and the microcontroller sends has an io buffer area which allows the rom running on the lynx to nav SD file structure to select ROM. Then have a command code to copy ROM from SD to SRAM or EEPROM, and have something disable the selection rom with high impedance, connect the game ROM, and force a reboot. Just not sure if it's possible to force that reboot without a power cycle. It's the reboot that is the sticking point IMO.
The biggest problem with that setup with SRAM, micro and SD card is how you get the bootstrap rom image into the SRAM quick enough for the lynx to start reading it. Ideally you'd hold the lynx in reset and load the ROM into SRAM then release it, but we cant do this. And you cant power the lynx on and off at will either, as the power is controlled by the soft on / off and a signal from Mikey.
If you went that route you'd need a boot ROM and SRAM and switch between using a mux or something to switch the chipselect line. So all a bit messy.
I have a cunning plan to get around all this... just thinking it through.
Oh and to reboot from software I believe you can just jump to FF80 with the Lynx ROM paged in.
Edited by SainT, Thu Jun 26, 2014 2:43 PM.