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@REPLYADDR Jeff Jonas <jeffj@panix.com>
@REPLYTO 2:5075/128 Jeff Jonas
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@TID: FIDOGATE-5.12-ge4e8b94
> Let`s not forget the Z80 itself was a new processor
> built upon an old design and became popular for that reason.
Yes, no, kinda, maybe?
8080 compatibility definitely helped on the software side,
running CP/M and such.
But the Z80`s hardware was tremendously easier to use,
almost like silicon-chip Lego, thus becoming the favorite for embedded systems
such as "smart modems", SCSI controllers, terminal servers.
In a way, the Z80 peripherals were "the tail wagging the dog"
because they were so popular, particularly the SIO dual-channel
serial I/O chips.
Z80 hardware features:
+5 volts only, no +/- 12v
single phase clock: no special clock generator required
Z80 native peripheral chips self-arbitrated DMA and vectored
interrupts via daisy-chain.
No interrupt controller required.
built in dram refresh cycle, making RAM interfacing easier.
The Z80 signals were so direct and easy to use
that they formed the basis of the STD bus (which was later extended).
I/O address space was separate from the 64k memory address space
due to IN, OUT instructions asserting the /IORQ signal instead of /MREQ
and other things :-)
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