25 Dec
2010
25 Dec
'10
11:30 a.m.
On 12/25/2010 01:18 PM, Chuck Guzis wrote:
On 25 Dec 2010 at 9:27, allison wrote:
You could if the EZ80 was compatible, in the extended mode its a
different beast. Since most CP/M apps are available as source
it's doable and could result in an interesting hybrid.
Really depends if you want to build with available through hole parts
and simple design or do a new and different thing. Neither is wrong,
just different paths.
Generally, a minimal cp/m system needs about 128K of "disk" for
common utilities and some tools. However thats a bit minimal.
I find none of the CP/M sytems I've used {still use} over the years
are limited if the disk is cramped. Whats cramped? Under about 500K.
At about 1MB it's decent, assuming you have at least 128K or more of
RW media. With large rams, CF or SD that can easily be large enough
to exceed the limits of standard CP/M2 (16 devices of 8MB each or
128MB. However I've been using large IDEs and CFs (16mb to 500mb)
for years and just mapping them in 8mb chunks (external partition table,
a new drive every +16384 LBA) and a simple utility to remap physical
to logical. the result is tiny, fast and runs anything CP/M.
The biggest issue is not the memory or mass storage system anymore.
It's IO, such as serial line for terminal (did that using FTDI serial to
usb)
I've done both bit bash serial and various serial devices (8250, SIO, 8251).
I've also tried memory mapped (16x64 like PT s100 board) video,
8Lx40char LCD (cramped), and so on. The ideal here would be USB
keyboard input (mac mini key board is very short) and VGA video where
the logic is I'm always near a VGA display and a USB keyboard. Then
with CMOS Z80 and and other parts, coompact portable is doable.
I believe something that is portable (battery or wall wart power)
is likely to appeal more to many with the right IO.
Allison
8080, 8085, NsC800, Z80, or Z180 cpu. The
prefered CPU is z80 as it's
easy to interface and there are some CP/M apps that require it.
If you're
starting off from scratch and want the smallest parts-count
system, why not an eZ80 Acclaim? 256KB of flash, 24-bit external
memory interface, built-in 100BaseT ethernet MAC, 2 UARTS, IrDA, lots
of GPIO pins, SPI, I2C and a PLL clock generator good to 50MHz as
well as ICE support and separately-powered RTC. Still Z80-compatible
(or the enhanced instruction set if you want it).
I suspect that you could dump most of what you need in the way of
CP/M programs into the on-chip flash. Add an external SRAM and
external interface "glue" and you're done, but for the programming.
--Chuck