I have an Apple II that will only boot into monitor mode. I suspect maybe the ROMs are bad. The autostart ROM had a broken pin, which I've temporarily fixed by jamming a wire in with the chip (before that, the computer wouldn't boot at all, no beeps)
Now the computer boots with two beeps, and this output: D3E5- A=01 X=00 Y=08 P=34 S=F4
...followed by the * prompt.
I'm pretty new to the Apple II, but these are my observations so far:
-I learned that the address for BASIC is E000. If I type E000G into the monitor it responds with that same hex output above. If I type E000G on my Apple IIc, it starts the BASIC prompt.
-The computer otherwise works: I suspect that if there was any damage to the board, or if any other chips weren't working, I wouldn't even get so far as the monitor prompt.
I suppose if I had a question to ask, it would be "is that definitely the problem?" As in: if I purchase replacement ROMs off eBay that are presumably in working order, and I put them in my Apple II, would this fix my problem? I'd hate to buy replacement ROMs and find that I still have problems...
A few weeks back I opened up an Apple II emulator and, for the heck of it, started listing the contents of the ROMS (F800L, F000L, etc.) and comparing with the contents of my Apple II. Everything initially seemed to match, until I listed D000. The memory at that location did not match the emulator's. I figured that was likely problematic
I recently got an Apple II Plus, and noticed the same ROM chips in it. I pulled out D0 (341-0011) and put it in the Apple II and wouldn't you know..... it worked! So the problem was definitely that ROM chip.