Hello all,
I am trying to "reverse engineer" some older 68HC11 based equipment. I got a hold of some nice circuit boards with general purpose I/O and since I liked working with 68HC11's some 10 years back I got nostalgic. Only thing is that these are 68HC11A0FN's and therefore without any programmable onboard ROM and there are a couple of things I am trying to figure out since I never dealt with those before.
The board's that I have are using 27C256 EEPROM and a very small serial EPROM that I don't remember the type of (until I get back home from work)
I want to replace the current EEPROM code with my own code but....where do I set the first instruction in the eeprom.
Correct me if I am wrong (It has been a while since i did HC11's): During reset the $FFFE and $FFFF hold the reset vector. But since there is no onbord ROM to program the $FFFE-F must lie on the extrernal EEPROM right??
Will I therefore program the reset vector with something like:
ORG $7FFF ; the last address in the EEPROM JMP $4000 ; Or whereever inside my EEPROM
ORG $4000 ;where the program sets registers and run code. program .....
Is this gonn'a work? Am I on the right track here?????
Any tips and tricks welcom
Thanks,
J=F3n F. Hjartar