BACK-OT: which CP/M machine is best (to copy)? :)

From: Joe <rigdonj_at_cfl.rr.com>
Date: Mon Aug 26 20:41:24 2002

At 05:08 PM 8/26/02 -0700, you wrote:
>Geoff Reed wrote:
>>
>> all of the CP/M machines I have here at the moment are serial terminal
>> based, I think that these are the rule, rather than the exception.
>
>Coolness. Maybe I'm asking all the wrong questions.
>
>The *right* question is: what terminal-based
>system would be good to use as a starting point/reference
>design? (i.e. "rip off and modify" :)


   How about the SB-180?


>
>That is: what's your favorite terminal-based
>CP/M system and why? :)

    GOOD performance (Hitachi 64180 aka Z180 CPU), GREAT OS (ZCPR). 256k or 512k DRAM memory, SCSI HD interface. also supports up to four floppy drives (3, 5 or 8 inch).

>
>Big points for:
>
> * Well-documented

    Published in a series in Byte magazine.


> * Available BIOS ASM sourcecode

    Not sure but very possibly published as well. But I'm pretty certain that several people have reverse engineered it by now.


> * Available schematics

   Again in Byte magazine.

> * Particularly popular, collectable appeal (might as
>well
> emulate something people like.)

    "Particularly popular"? Perhaps not but still popular.


> * Unusually clever, minimalist, or just "good" designs.

     GREAT design IMHO. Designed by Steve Ciarcia.
>
>It would be so cool to get a fast Z180 adapted to fit
>as a superfast CP/M replica. :)

     Original SB-180 design used a 6MHz 64180 (Z-180) and was later upgraded to 8 MHz but a friend of mine has just gotten his to run at 22 MHz! (See message below).


"I have finally gotten an SB180 floppy system running
at 22 MHz. The system starts at 11MHz in EPROM, loads
a boot-track image of B/P bios, which then loads a full
banked-image. The banked-image makes the transition
to 22 MHz. The banked-image also has code to drop the
clock rate back down to 11 MHz and insert io wait states
when accessing the FDC chip. So, it is running at 22 MHz
with no memory or io wait states when it is not accessing
the floppy. Zippy little bugger!

I also added code to use the Z8S180 ESCC-like BRG, which
lets me run my terminal at 115.2k baud. (I use a P133
running Linux with a Digiboard multiport serial card as
a terminal.) My FX at 9MHz and 19200 now seems to crawl...

I am going to plug in the SB180 SCSI expansion board and
a SCSI drive and see if the system has any trouble with
the SCSI IO at these speeds. If it works then I am going
to migrate this to my original SB180 system, and then
move on to speeding up my FX system."

    joe


>
Received on Mon Aug 26 2002 - 20:41:24 BST