Date   : Thu, 04 Nov 1982 09:50:00 EST
From   : clark.wbst@Parc-Maxc
Subject: Re: Godbout 8085/8088

About your 7E's...  it has been a while, but am pretty sure that 7E is the
opcode of the instruction your monitor uses to do the memory fetch,
probably a 'MOV A,M'.  I have had this before...  First I will explain
where I have seen it; I don't see a clear match with your problem,
but then I am not familiar with your hardware...

If you have a processor with no buffering, when you do the MOV A,M
the opcode (7E?) gets put on the bus.  When the processor does the read
the bus is tri-stated, and the opcode is still hanging around from
capacitance.  Since there is no memory out there, nobody drives the
bus, so you read the opcode.  If you have a running processor you
can see this by writing a memory poker that uses a different instruction,
like ldax b or d... then you see their opcode.

This certainly would not explain your problem with EI's etc.  Actually,
not much of anything would run since on the 8080 all jumps, ret, and
I think calls have the upper bit set.  Since you DID seem to get the memory
dumper of some description to run, it must not drop them ALL the time.

Anyway, good luck !    I hope this helped some...

                               --Ray Clark