9815 peripherals - rom images ?

[artag]

(12-19-2022 03:35 PM)vassilisprevelakis Wrote:  Since the 9815 must be able to read these ROMs over the bus, my guess is that a simple device like an Arduino connected to the bus (pretending to be the 9815) should be able to read the ROM.

Yes, that was my first thought, too. The original roms do need some weird voltages but it's not impossible and of course the cartridge itself contains the pin drivers.

Another option is to catch the data from the bus with a USB logic analyzer. I haven't checked but it's possible the initialization runs through the entire rom space to do a checksum.

Finally, it might be possible to create a new cartridge using a modern rom to provide a debug monitor capable of doing the usual microprocessor operations such as dumping memory. There are a number of 6800 monitors around the net which might do, and it has several other uses for maintenance. The downside of this is that you really want another interface such as serial on which to dump the data.

There was some discussion in the past about a built-in extension rom in the 9815S upgrade. Did anyone ever determine what it was ? It might be the maintenance rom ..