Just picked up an 130XE and it doesn't quite work as intended. It immediately boots into the ROM/RAM self test and doesn't respond much to keyboard input. In the self test it claims the second ROM to be faulty, which seems legit since I can't get access to the Basic prompt. Note that all the RAM tests out fine I just didn't wait for it reach the end in the picture below.
1st, there´s no second ROM - the left block indicates the frist 8 KByte of the O.S. ROM area between $C000 and $DFFF (incl. Selftest mirrored from $D000-$D7FF to $5000-$57FF) and the right block shows the checksum test result of the $E000-$FFFF area (also 8 KB). The complete 16 KB are located in one chip. The BASIC ROM was not recognized by the Selftest.
Because the computer boots straight into the Selftest, but shows no defect RAMs, IMHO only three options possible:
- Just a bloody simple short to ground (read below)
- Defect O.S. ROM
- Defect MMU
This order beginning with the upmost probability
What I mean with the first bullet point is: Check first if only a short-circuit of one of the cartridge´s / ECI´s connector pins has contact to the metal grounding plate. I´ve seen many XE systems, where the pins aren´t shortened (cutted), specially at the ECI port (2x 7 pins). Atari didn´t insert any fishpaper between the metal plate and PCB, so if there´s one of the pins too long, it might have contact to ground in same cases. Sometimes the computer doesn´t boot, sometimes this failure happens..
So simply re-test the board without metal plate loose, when the XE boots into READY prompt, you know what to do - cut the too long pins, that´s all.