Re: eZ80 Single-Board Computer

On Thu, 23 Aug 2007 00:37:07 -0700, "hharte@xxxxxxxxxxxx"
<hharte@xxxxxxxxxxxx> wrote:


HD64180 based:
SB180 with SCSI board
Z180 on S100 via modified SB880 board.

Z180 based:
Homebrew 10mhz, 1mb ram, IDE

Z280 based:
Z280 on ISA, uses a 16bit ISA bus and IO, FDC and Video.
Z280 stand alone, 8mb ram, 1mb eprom, IDE serial IO (x4) 12.5mhz

They all run CP/M or it's upgrade replacements. However one of the
S100 crates and the z280 run a varient of CP/M with added task
switching software for background work and other multitasking
experiments.

Allison


Would you be interested in an S-100 CPU card with an eZ80 on it? I'm
planning on an S-100 base-board that the eZ80SBC can plug into. This
would allow the eZ80SBC to run the S-100 crate and access S-100
peripherals.

Not really, I have many S100 Z80 boards like:

NS* (cpu with Z80)
one modded for a 10mhz z84c50 (see below)
two are stock
CCS (CPU with Z80)
Compupro (CPUwith Z80)
SBC880 a second one, (CPU with z80)

2 SBC type z80 s100 systems on a board (z80, 128k, FDC, 2serial,
Parallel printer)
2 SBC type Z80 S100 systems on a board as slaves (Z80, 128k, 2 serial)

What the eZ80 lacks in memory management, it makes up for in I/O
flexibility.

That is a serious flaw as memory management in a z80 (64k) environment
means you need efficient ways to change memory context becuase you
will likely have to do it often.

It has really nice programmable wait-state generators
and bus timing to allow the 50MHz CPU to access slow I/O or memory.

The Z80 (84c50 flavor), Z180 and Z280 all had programable wait state
control logic. the Z180S00 is available in fast (33mhz) or at least
it was.

You missed out on the 84C50, pin compatable CMOS Z80 available
to 10mhz (I have a few) internal wait state controls and 1k of
internal ram. the nice part is you can drop it in a standard Z80
socket.

The internal wait state controller allow adding waits on Instruction
fetch, regular memory IO and IO cycles independently.

The 1k memory is relocateable and can be used anywhere in the
memory map and has faster access than external memory. It makes
a 64k bank mapped system nice as it gives the needed small amount
of common memory.

I've been actively using CP/M since first system back before '77ish
and when I moved to V.2.2 in early '80 I started exploring
multiprocessors and multitasking to expand and enhance. Along
the way I built a few systems and aquired a few some of which I had
more than one of and so the second was always "enhanced" in some
way to explore hardware and software beyond the usual stuff.


Allison

-Howard

.

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