Nice simple 1200XL OS upgrade using Channel Select switch
I've attached the ROM files for both U12 and U13 which are the two OS chips on the 1200XL motherboard. The stock 1200XL uses two 24 pin ROMs that are 8K each. In Atari's infinite wisdom, they included the traces for 28 pin EPROMs. The upgrade is not too hard and cosmetically leaves the 1200XL looking stock.
Steps:
1) Remove the 24 pin ROMs (U12 and U13).
2) If the socket is 24 pin you need to add the two pins on each side or replace the whole socket with a 28 pin socket. The forme
fixed the "R" to correct "W" reference. Thanks DrVenkman!
I've attached the ROM files for both U12 and U13 which are the two OS chips on the 1200XL motherboard. The stock 1200XL uses two 24 pin ROMs that are 8K each. In Atari's infinite wisdom, they included the traces for 28 pin EPROMs. The upgrade is not too hard and cosmetically leaves the 1200XL looking stock.
Steps:
1) Remove the 24 pin ROMs (U12 and U13).
2) If the socket is 24 pin you need to add the two
