3 Oct
2023
3 Oct
'23
1:46 p.m.
Wouter de Waal via cctalk wrote:
Hi all
I re-discovered some eurocards I found in a box at a swapmeet long ago.
It looks like a complete 8085 system. Lots of RAM, 2K EPROM, I/O, FDC.
The strange thing is that the EPROM is mapped at F800, the code in there
looks like 8085 code, and looks like it wants to live at F800. And there's
RAM at 0000.
The DIN41612 A/C 64 pin bus has provision for 16 bits data.
Pics here http://retro.co.za/8085/Microcom/
Anyone maybe have more information on this? I'm curious.
W
Besides of relocating the entire ROM temporarly to 0x0 there are other
possibilities, for example placing NOP's (0x0) on the data bus until
the bus addresses reaching 0xf800 for the first time. This way a few
extra gates and a flipflop is all what you need.
On Z80 Systems I've mostly used a mechanism that enables writes to the
RAM at 0x0, but the reads came from the ROM until an flipflop was set
by an out instruction (and reset by Reset).
Regards,
Holm
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