Are z80's still being produced? If so, are they the same as the 1980
ones? I would think so, since the TI-86 (still in production) uses
a z80. BTW, I guess comparing the multi-Z80 system to a 386 isn't too
fair. How much faster is it than 1 z80 running the same program? Why
is everyone making multi-z80 machines, anyway? Why not 6502 or 6800
or even (gasp!) 8088?
>< connections is good, soldering them helped a bit but no dice.
>
>Huh? I have 6 cards, s100 protoboards with about 25-40 pieces of mos
and
>TTL on them that I wrapped in 1981 still running. Ohmic losses? What
were
>you doing wrong. Remember #30 is for signals not power!
>
>< Have data transfers done with DMA, all memory mapped and irq driven
>< to knock subCPU as needed to grab data then place it in CPU's lap.
>< Leave CPU alone for processing. How about that?
>
>Those 6 boards built a multi z80 system with DMA and slave processors
for
>things like IO and disks. It helps but the z80 bus is so busy that
it's
>very hard to slip inbetween cycles so you steal cpu cycles by holding
it
>off with BUSRQ/. Z280, z8000 and Z380 use burst mode access to the bus
so
>that other devices can get in and get a few cycles without holding up
the
>cpu. Even with slaves you reach a bottleneck between memory management
>and overhead to move data around. Still the results with 6mhz z80s
were
>enough to blow away 386/16 class machine for text oriented
applications.
>
>Allison
>
>
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Received on Fri Oct 23 1998 - 18:41:08 BST