I've definitely dealt with my fair share of having to reseat chips, restoring some computers in my free time.

Sadly though, I put the old processor back in, and the behavior returned. No sweat though, I will get another one and the GAL chip to restore my Apple IIe, and enjoy my now working ...

Ha, I should have clarified, yes I got married.

Thanks so much!

After a marriage and finally settling into a new place, I've FINALLY had time to sit down and debug this thing.

So everyone, I've finally found the problem.

I narrowed it down based on some other strange behavior on my monitor program. I noticed when I put code in certain locations in the monitor ...

I know we're a few months removed here, so I apologize for the bad form. I had to pack up and move and have only recently got the thing set up again. I didn't think I should make a whole new post just to tackle the same issue. I've tried all of the suggestions to no avail. I've made a single stepper ...

Thanks a million everyone for the help. I'm out all weekend so I can't try these fixes atm, but that linked forum thread duplicates my issues with my same kind of setup. So I'm going to try the fixes in the other post, see if they work.

I'll also implement this Mem test and clear decimal before ...

So just a few updates. The keyboard interface broke (flimsy PS/2 socket), so I've since ported the monitor and basic to run off of my ACIA in the meantime (I have more sockets coming. I'm going to find a way to make it stronger). After finding out I had one with the TXE bug, I've got it displaying ...

It's also possible I have the decoding wrong to begin with.

Because come to think of it, I remember reading at the bottom of the first example in Garth's primer, I see that each device would have a unique range where an address ISN'T mirrored anywhere else. If I'm understanding this right, then my ...

The speed of your RAM is no issue - you don't need to change that! (If it were an issue - why should your monitor work then?)

If you key in a line starting with a number - does BASIC crash?
If you then type LIST - does a listing appear or does it crash?

Did you try to use BASICs POKE function ...

So, I've set Ibuffs in the appropriate place and still nothing. If I do PRINT "A", the whole system crashes and reboots. Even to the point where I can see the LCD dim, which suggests its ground it being affected. I don't know how normal this is, or isn't.

The only thing I'm starting to suspect now ...

... ECHO restores acc before RTS. This is accomplished by first storing the ACC at a location outside of user RAM, and then LDA with that address before doing an RTS. PLA/PHA instructions cause it not to work properly. (Nothing gets displayed)
That's worrisome (assuming that you were doing the PHA ...

Unfortunately I cannot single step. I will check with my voltmeter when I can to see what it is doing.

I have now set my RAM within in these parameters, but still no luck.

As far as I can tell, my RAM is good. I haven't implemented a test in my monitor, but I have manually keyed in programs into ...

It does, yes. Also, another weird bug. PRINT "TEST" gives me a mismatch error. I should wait until I have 40 column screen to see everything. Or just port this for my ACIA in the mean time.

So I currently do have it set where if no character is present, it clears carry and returns. It doesn't keep scanning the keyboard. If a key is pressed, it's loaded into the acc, carry set, and return. So it doesn't loop waiting for just a key press like before.

Still though, no luck. A few times ...

I think V_INPT should not wait for a char, just return the C flag to indicate Acc contains a char.

For example:

V_INPT
LDA VIAORB ; LOAD THE VALUE OF VIA PORT B. KBD DATA READY LINE IS HERE
AND #@00001000 (Is this the correct mask for kbd ready?) ; IS DATA READY LOW?
CLC
BNE V_INPT9
LDA ...

At


V_INPT

KEYSCAN:
LDA VIAORB ; LOAD THE VALUE OF VIA PORT B. KBD DATA READY LINE IS HERE
CMP #@00000111 ; IS DATA READY LOW?
BEQ LOADKEY ; YES, LOAD KEY DATA
JMP KEYSCAN ; NO, KEEP SCANNING DATA READY
LOADKEY: LDA VI2ORA ; LOAD ACC WITH ASCII DATA FROM KEYBOARD
RTS ; GO BACK TO WHERE ...