Electronics > Projects, Designs, and Technical Stuff
Found a weird old computer dumpster diving. (z80?)
tsvisimcha:
Under the speaker
tsvisimcha:
Another angle
tsvisimcha:
I have a bus pirate somewhere so I can try to dump the eeprom if someone wants to take a look at it.
rstofer:
--- Quote from: tsvisimcha on March 28, 2020, 05:54:54 pm ---I have a bus pirate somewhere so I can try to dump the eeprom if someone wants to take a look at it.
--- End quote ---
Disassembly from a ROM dump is a fool's exercise. All the author needs to do is put in some bogus 0x21 (LXI H) bytes to throw off disassembly. The next two bytes would be an operand for the LXI H but are actually the start of some other instruction because the LXI H is never executed. The BDOS component of CP/M has this feature. Or at least that's what I came up with when I tried to disassemble it. The first byte of any other multi-byte instruction will do the same thing.
Just scatter so DB 0x21 instructions in the code.
rstofer:
It might be better to remove the speaker completely. The Z80 and the NVRAM are pretty sweet. I don't care for desoldering but I might make an exception. I have several Z80 systems including a complete CP/M system running on a 50 MHz eZ80. The system just screams at that speed!
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