How to read and interpret Apple //(e) monitor error codes like ...

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tokabln's picture
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How to read and interpret Apple //(e) monitor error codes like ...

"-0803 A=00 X=60 Y=00 P=34 S=F5" ?

Is there anyone able to explain or is there a describing document available anywhere?

Many thanks in advance

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Re: How to read and interpret Apple //(e) monitor error ...

..

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Re: How to read and interpret Apple //(e) monitor error ...

-0803 A=00 X=60 Y=00 P=34 S=F5" translates to:

BRK instruction ($00) encountered/executed at address $0803 with CPU register A (Accumulator), X, Y, P (Processor Status flag bits), and S (Stack pointer) values.

tokabln's picture
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Re: How to read and interpret Apple //(e) monitor error ...

Many thanks...

so if such a message occurs during startup, I then should take a look into the ROM routines (here at adress 0803 - is this hex?) to see why this error probably happens, right?

Does anyone know where I can find a document describing the ROM content (commented disassembled ROM) covering the Apple //e ROMs?

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Re: How to read and interpret Apple //(e) monitor error ...

tokabln wrote:

so if such a message occurs during startup, I then should take a look into the ROM routines (here at adress 0803 - is this hex?) to see why this error probably happens, right?

The RAMs are also suspicious. The stack uses RAM. Other causes of such faults can be line drivers (issue of timing).

Mentioned in another posting for download:
Apple_IIE_Technical_Reference_Manual.pdf
which includes ROM-Listings.

Regards, Ralf

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Re: How to read and interpret Apple //(e) monitor error ...

tokabln wrote:
Many thanks...

so if such a message occurs during startup, I then should take a look into the ROM routines (here at adress 0803 - is this hex?) to see why this error probably happens, right?

No, address $0803 is in RAM and commonly used by programs and bootstrap loaders that start at location $0800. When you see the "error" display you mentioned it just means that a program has gone awry and tried to execute code at that location when its contents are probably not correct (possibly overridden by some other errant code). It COULD also indicate a hardware issue (most probably RAM) but more likely to be a software crash.

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Re: How to read and interpret Apple //(e) monitor error ...

Ah... okay and understand. Many thanks for your explanation.

It now makes sense to me, because I'm using / testing a card that should act as boot device and at some circumstances this error occurs.

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Re: How to read and interpret Apple //(e) monitor error ...

jeffmazur wrote:
-0803 A=00 X=60 Y=00 P=34 S=F5" translates to:

BRK instruction ($00) encountered/executed at address $0803 with CPU register A (Accumulator), X, Y, P (Processor Status flag bits), and S (Stack pointer) values.


Minor point of clarification: the 6502 increments the PC after BRK, so the actual BRK occurred two or three bytes earlier than the address that the Monitor prints.

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Re: How to read and interpret Apple //(e) monitor error ...

Ah... good to know. Many thanks.

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