>error code 41, what does it really mean "selection logic problem" ?
>Is there anywhere some description about the selection logic?
Most of the error codes are not very well explained, but one can examine the ROM listing to get an idea of what causes a particular error code.
The ROM listing is available from a few sites, one being:
http://www.1000bit.it/support/manuali/apple/lisa/lisaBOOTROMLISTING.pdf
Looking in the section labelled "Equates for error codes displayed to user", one can see that the symbol name ECPUSEL is assigned the value for error 41.
A search of the listing for ECPUSEL show it appears at $13DE, and looking at the surrounding code, this is a result of the "CPUSEL" bit having been set in D7 (which happens to be used as an error "accumulator" during the self-test).
A search for CPUSEL reveals that the CPUSEL bit is set in the code preceding $0B8E in the listing. It appears this is generated when an test access of VIA1 (6522) fails with a bus error (a bus error occurs when nothing responds to an address by asserting DTACK or VPA, and the CPU gives up waiting). If the I/O Board is missing some parts in the circuitry that generates DTACK and VPA, this is not too surprising.
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