Xerox 820 system disks in Teledisk format? - test-drb@ccmp.vtda.org

8 May 2009

-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of Chuck Guzis
Sent: Thursday, May 07, 2009 5:35 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Xerox 820 system disks in Teledisk format?

On 7 May 2009 at 13:47, Jules Richardson wrote:

...
  No, I suppose not. I wonder if they ever toyed with
the idea of
 rolling their own - perhaps a board containing a little 8-bitter which
 was responsible for a few other useful functions (RS232, parallel
 maybe) too. I suppose RAM/ROM costs around then made it unworkable
 even if they had the skills readily on-tap (not to mention that it
 probably wouldn't fit in with the idea of what the PC was supposed to
 be!) 
Commodore 1541?   Actually, they'd done that one already.  Think 
about the IBM 5100/5110 with the 5114 diskette drive unit.  I don't 
think they even wanted to think about putting something like that on 
a "personal computer"...

--Chuck

-----REPLY-----

Hi Chuck, Jules!  At least in theory, the N8VEM SBC mated with its Disk IO
board provides this capability right now.  The N8VEM SBC has 512K SRAM
for immediate storage, the Disk IO supports IDE and NEC765 FDC
capability.  Attach a IDE to CF adapter (several varieties of those have
been demonstrated to work or just use an old IDE hard drive) for storage
and use the SBC serial port for operator IO.  

Connect the SBC to the Disk IO board via a 64 pin DIN 41612 IDC
connector and short 64 conductor ribbon cable for a nice and compact two
board (stacked Eurocard) solution powered by 5VDC only.  The SBC boots
CP/M 2.2 from its ROM drive which could be easily augmented with CP/M
applications to manage the floppy disk transfer functionality.  I
designed the system with something like this in mind and there are at
least the beginnings of the software necessary to accomplish it.  The
Disk IO board even includes special control and data signal access for
raw disk reads and 8" floppy drive manipulation if someone were *REALLY*
ambitious.

I spent quite a bit of time working on this design along those lines but
the Disk IO was such a beast I rather burned out on it.  Since the PCBs
and parts are all available now if someone wanted to pick this up the
hardware is essentially completed, some of the software, and you're most
of the way there.  It would "only" take someone with the desire to write
the software to make this happen -- basically comfortable old CP/M and
Z80 assembler.  I've moved on to other things in the N8VEM project.

Thanks and have a nice day!

Andrew Lynch