"-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
Anonymous
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-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.
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?
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
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.
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.
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.
Ah... good to know. Many thanks.