I've spent a couple of days disassembling the Mensh ROM present in the w65c265s MCU.

My goal is (still untested, though) to burn it to an EEPROM and make the MCU boot from it instead of the internal ROM included in the chip itself.

So I made a dump from $E000 to $FFFF, loaded it in 6502 bench, and compared it to the 265iromlist.pdf file that you can download from WDC's website, recreating the subroutines one by one.

I still have to test it to be sure that it works. It compiles, both in its original $E000 destination, and also relocated to $8000.

Apart from my own feeling of accomplishment and enjoyement (because I can't do anything more with it like, you know... adding things or fixing bugs), is it worth of anything?

Would be anyone interested of having the sources I created from the binaries, in the case they work?

I'd be curious about them. Specifically I wonder how much state the monitor maintains.

For example does the monitor avoid using page zero? If it does have a work area in RAM, how big is it?

It’ll be interesting to see how realty compares with the official documentation.

https://www.wdc65xx.com/wdc/documentation/265iromlist.pdf