Apple II boot problem

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Joined: Feb 21 2006
Posts: 21

Hi,

I'd like to get this Apple II working. With no diskette drives attached (and no associated disk card installed), when I power up the machine, it does the quick double beep, the "APPLE ][" shows up on the screen and the very next line says something like:

DBxx A=xx X=00 Y=xx P=xx S=xx
*

where xx is a different 2-character hex number

I've pried up one end of each socketed chip on the motherboard and see-sawed them back in (counts as reseating the chips, right?). The only card installed is a Language Card (I don't know the model, etc off the top of my head). And it is a Apple II, not a Apple II+, IIe, MacBook.

Any ideas?

Scott

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Offline
Joined: Feb 17 2008
Posts: 195
Hopefully some members will h

Hopefully some members will have some suggestions, but for a start try removing the Language Card and booting up. I also have a Apple II non-plus which boots up OK, but has issues with the current language card.

You own a piece of history.
It will work. Don't give up.

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Joined: Apr 11 2006
Posts: 1013
Re: Apple II boot problem

swapple wrote:

when I power up the machine, it does the quick double beep, the "APPLE ][" shows up on the screen and the very next line says something like:

DBxx A=xx X=00 Y=xx P=xx S=xx
*

Ok, the basic power-up circuitry is working. You get the initial beep with the APPLE ][ display, and then the second beep is the ROM crashing while it's trying to run its code - and that's the DBxx... display you see. Did you reseat the ROMs - the large-ish chips in the middle of the board? One might not be making a connection or might just be bad. Can you list the part numbers you have on them, too? You should have four or five, and will start with 341-.

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Joined: Jun 5 2008
Posts: 382
Diagnosing these machines rem

Diagnosing these machines remotely, is a difficult, at best. The good news is that getting as far as it does, indicates that your machine doesn't have a lot wrong with it.

Must be Applesoft ROMs in this machine, since it is displaying the "Apple II" prompt.

Note that the DBxx is an address in PROM D8. The language card also uses this address space when enabled. I second the thought about removing the language card (make sure that you transplant a 4116 DRAM chip to the now empty motherboard socket after pulling the card).

I could easily imagine where a bad motherboard DRAM chip (1st bank) or a problem in the address decode logic could cause similar behavior.

Make sure that you have all the correct chips positioned correctly, in the correct places and that there are no bent under pins, anywhere.

Regards,
Mike Willegal

resman's picture
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Joined: Feb 9 2006
Posts: 214
Oxidized ROM pins

I had a ROM chip (Programmers Aid #1) that exhibited similar behavior. After carefully cleaning the pins with a pencil eraser, it worked fine. Also, Mike, my Integer Basic ROMs display APPLE ][ at the top. Are you saying it has AutoStart ROMs in because he didn't have to hit reset first? I think the Apple language card came with the AutoStart F8 ROM (at least mine has one).

Dave...

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Joined: Apr 11 2006
Posts: 1013
Yep, the OP says he had a lan

Yep, swapple says he had a language card plugged in... that would give him the autostart.

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Joined: Jun 5 2008
Posts: 382
I wasn't aware that autostart

I wasn't aware that autostart F8 roms were provided with language cards for integer basic machines (original Apple II). Thanks for the information.

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Joined: Feb 21 2006
Posts: 21
Thanks! I'm going in.

Thanks for the suggestions. I'm going to dig into it today.

On a whim I had already tried removing the language card, but without a replacement DRAM chip, I was expecting not to get far... and didn't.

I'll try completely reseating the PROMS (and maybe more). I had already lifted one end of each socketed chip and pushed it back in, which causes the other end to rise slightly and then push that in. That's the see-saw action I was referring to.

Question: Does it tell us anything that the "xx"'s in "DBxx A=xx ..." are different each time? If they do repeat, I haven't noticed a pattern.

Scott

resman's picture
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Joined: Feb 9 2006
Posts: 214
Swap RAM rows

Fill the missing RAM chip from the language card. After cleaning up the ROM pins, you could try swapping rows of RAM chips. Low memory is critical for proper booting. If one of the RAM chips is bad, it would cause problems. As for the xx value being different, it sound like something is on the edge. Oxidized ROM pins can act that way by sometimes returning the correct value, sometimes not. Of course many problems could manifest themselves this way, but look for the easiest to fix first.

Dave...

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Joined: Jul 16 2006
Posts: 81
I have an apple II+ that beha

I have an apple II+ that behaved in a similar way. It took months to find what was wrong with it, even with a mixed signal oscilloscope. I even gave up at one point, but came back after a while. But now it works, and it has its own permanent place on my desk Wink

In my case, there were two faulty chips: one bus driver and one DRAM (maybe it was two, can't remember). The reason they broke (MANY years ago) was that my father removed or inserted an expansion card while the Apple was still on, probably causing a short-circuit on the data bus.

What you could do if you have an oscilloscope available is to look at all the data signals and all the address signals when powering on the Apple. If a bus driver is broken, its data or address signal will look different from the others. You might even be able to do this with an old analog oscilloscope. This step lead me to the broken bus driver.

Also, you shold try looking at the exact error message, and see if there's any repeatability. If there is, try swapping the bus drivers, or the DRAMs. See if the pattern changes. If it does you'll know you are on the right track. This method lead me to the broken DRAM.

Of course, reseating all the ICs is a good idea, but it won't fix any broken ICs...

I also want to recommend this site for ordering replacement IC's: http://www.arcadechips.com/

Cheers,
Jakob

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Joined: Feb 21 2006
Posts: 21
It's working!

Thanks all for the suggestions *and* background information. Its running! I typed in a BASIC program which RUN'd fine and booted it from floppy. It's all good!

Scott

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Joined: Dec 19 2003
Posts: 832
What'd take?

What was the cure?

Mutant_Pie

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Joined: Feb 21 2006
Posts: 21
Re: What'd take?

mutant_pie wrote:

What was the cure?

Mutant_Pie

Oops! Sorry!

Completely removing the ROMs and putting 'em back in!

Scott

themike's picture
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Joined: Jul 21 2004
Posts: 455
So simple! Got to love those

So simple! Got to love those old Apples...

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Joined: Apr 24 2011
Posts: 9
Re: Apple II boot problem

ive seen some things like this problem. it is making it pass the low memtest are you would get jest random chrs blocks on screen; if i where going for mem i would look hard at the second 2 banks, or a combination of dirty roms and mem sockets i was jest wondering
did you get it fixed yet; ](blinky)
oxidation is a real problem Sad
good luck;
kdhill