Minimal CP-M SBC design

[Ethan Dicks]

On Sun, May 11, 2008 at 08:23:13AM -0400, Dave McGuire wrote:
>   Well I wasn't talking about a diskless system...only one in which 
> CP/M itself was in ROM.

I personally find the idea intriguing, and I am about to cobble up
a system from (nearly) scratch.  I used Kaypros and the like, back
in the day, and really won't miss floppies (not that there's an FDC
chip within 3000 miles I could slap on this thing, anyway).

I don't mind the idea of stuffing "the OS" in ROM vs loading off
of removable media since I doubt I'll want to upgrade.  I want to
run a few CP/M-80 programs, and that's about it.

> >I still don't have the hang of this "vintage" thing yet, probably 
> >because I'm vintage myself.  Please forgive my density...
> 
>   I often suffer from the same problem.  I think very few of us, even 
> here, actually used stuff like CP/M and PDP-11s when they were 
> considered current technology.

I was a kid when S-100 machines were "in", but, as came up earlier
in this thread, I did hit the Osborne/Kaypro CP/M era.

I consider myself quite fortunate that I've gotten to program PDP-11s
on two different jobs right at the tail end of their heyday (I was 18-20
at the time).  I also consider myself fortunate that I was working at
a place that supported VAX/BSD customers in addition to our VAX/VMS
customers, so I was able to pick up some UNIX skills nearly 25 years
ago.  When folks bandy about "All the World's a VAX", it really means
something to me (I learned C from K&R on an 11/750 running 4.1BSD, so
I _know_ how easy it is to write non-portable code).

I do run things inemulation, but I also enjoy running things on real
iron.  Right now, I have a modern Elf within reach, as well as an
SBC6120.  The SBC6120 boots off of CF... no floppies, no 1/3 HP rotating
media, but there's still a real 12-bit processor on the board.  I don't
consider that emulation in the slightest, even if my "disks" don't rotate.
OTOH, I also have, at home, "real" PDP-8s with real DEC-made disks; they
just aren't so portable as to be worth hauling down here.  Same goes for
a CP/M machine - I'm working on something smaller than a princess phone.
Quite portable compared to an S-100 or an Osborne.

Just my take on why I mix classic CPUs with modern peripherals... runs
the original software, weighs a lot less.

-ethan

-- 
Ethan Dicks, A-333-S     Current South Pole Weather at 11-May-2008 at 12:40 Z
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Ethan.Dicks at usap.gov            http://penguincentral.com/penguincentral.html