Re: Gemini 80-Bus System
Just to recap...
There is no Address/Data bus activity when checking at the Z80 processor pins with a scope. The clock is present and looks good.
The z80 chip has been replaced with a known good one and for completeness the Z80 from the Galaxy has been shown to work fine in another system.
The Simon ROM (2716) has been swapped for a known good RP/M 2.3 (2732) along with the appropriate link change LK4/5 to support the larger ROM size. I even tried it running the system with RAM removed followed by PIO/UART removed.
The Simon ROM has now been dumped and looks OK but I have yet to compare byte for byte.
Following JBH's advice I tried the GM813 in a Gemini rack system using an IVC display card and GM829 disk controller. All that happens is that the IVC reports the IVC Rom version. For completeness I placed the rack's G811 and MAP80 RAM in the Galaxy system and the machine booted to RP/M.
I will put the Galaxy back together with just the GM813 and SVC Card with the 813 in the top slot as that way I can access the board with a scope and logic probe.
One thing I would mention is that despite owning a scope and a logic probe, I am no expert at this stuff, learning all of the time though.
JBH: If I put the 849 MFB in with the 811 and IVC (Is this combination of cards safe?) and run BASIC under RP/M (from Tape), would running your program give you what you need?
John
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