Hey guys, I am probably overlooking something silly, but I am a bit stuck.
- I got Petari's awesome TOS Improved 2 versions, and Atari's original TOS 1.04, 2.06
- On 2x 27c4001 EEPROMs
- A17 and A18 (Pin 30, 31) are TOS toggles. This seems to be working. Switch off has both pins at 5v. I used 33ohm resistors I had laying around, is this high enough for protection?
- With both switches grounded, A17 and A18 low, it successfully boots TOS 1.04 original.
I can't get the other three versions to boot, and am not sure what to check next.
I have a strange revision of 520 STFM, ROMs are under the PSU, 2 chip version. So, to be less cramped and reduce the chance of ROMs, GAL shorting to the bottom of the PSU shield, I actually installed the GAL on top of the 68k, and ran a fairly long CE1 line from GAL 15 pin to Pin 22 of new ROMs.
- Pin 24 on new ROMs are pulled up from the socket, connected to GND on mono. (OE)
- Under pin 24, I ran A16 to Pin 2 of new ROMs.
- GAL pin 15 CE1 is running to Pin 22 of new ROMs. This pin is inserted in the socket still.
- When I unsoldered the CE blob jumper on the board, TOS 1.04 original quit working until I soldered it back on 1M pad.
- A16 and A17 pads are still soldered on 1M like stock.
I hope this is enough info to start. Thanks in advance for nay help anyone can offer. I am rather confused at this point. lol