Extracting CDOS and CP/M) files

Roy J. Tellason rtellason at verizon.net
Fri Oct 12 20:00:18 CDT 2007

On Friday 12 October 2007 18:15, M H Stein wrote:
> ------------Original Message:
> Date: Fri, 12 Oct 2007 16:43:03 -0400
> From: "Roy J. Tellason" <rtellason at verizon.net>
> Subject: Re: Extracting CDOS and CP/M) files
> On Friday 12 October 2007 03:23, M H Stein wrote:
> <snip>
> > Want to copy your SDSS 8" disk to a DDDS 5" one? No problem.
> > Friend or business partner has some data on SDSS 5" disks that you
> > want on DDDS 8"? Just pop in the disks and copy away; add some
> > software and you can even copy to/from MS-DOS disks if you must.
> > Run Z80 CDOS/CP/M Wordstar on your 68000 Cromix+ CS-400?
> > No sweat (although a different issue). Process your old CDOS data
> > files with your UNIX software? Not much harder.
> >
> > It all just looks different from today's PC-centric perspective.
> So what sort of hardware does it take to be able to do stuff like that?
> I know my Bigboard II has both sizes of floppy drive connectors,  though I
> think there's a jumper change involved to deal with different data rates
> IIRC.  And there might be some potential for that board that's in my
> Cromemco,  as well.
> I'm sure that a lot of my CP/M boxes have controller chips that are much
> more capable than the pc-centric stuff is,  too.
> And how would the OS have to handle this?  Some serious BIOS hacking?
> ---------Reply:
> The simple answer for a Cromemco box is a minimum configuration of a DPU,
> 16/64FDC, 128KB of memory and optionally a hard disk & controller.
> (You'd need somewhat more to run UNIX).

That's more than I've got in there.  It's a ZPU,  64KB ram card,  I *think* 
that 64FDC,  and an I/O card,  not real sure but I think maybe it's the 

> AFAIK, as far as Cromemco systems go (assuming a 16FDC controller or later,
> and soft-sector disks):
> CDOS can read/write any one of the 8 (10?)possible CDOS formats and 8"SSSD
> CP/M (which, essentially being the first floppy "standard", was a
> more-or-less universal distribution medium for software such as WordStar,
> SuperCalc etc).

No CDOS handy,  I'm not even sure what I got for disks with that box,  though 
I did get some,  the problem with the drive having done some physical damage 
to the one that was in it.  Somewhere around here I have a box of 8" 
floppies,  but that would include what came with this system and also what 
came with the Imsai,  at least,  plus probably some stuff that folks have 
sent my way over the years.

> Third-party software was available to handle other formats, and there were
> also custom versions of CP/M configured for a Z80 Cromemco.

I'm not sure if I even have CP/M specific to that box.

Mostly I was looking for what sort of hardware capabilities would be needed...

> CDOS itself is a clone of an early 1.x version of CP/M, which Cromemco
> licenced from DRI and enhanced somewhat with some additional calls, and it
> can run most CP/M software (at least early pre-2.x versions).

I don't think I've ever actually seen anything WRT 1.x,  or if I have it's 
been so long ago that I've forgotten.

> Any version of Cromix (Cromemco's early Z80 and 68000 pseudo-UNIX) can
> read/write any version of CDOS or Cromix disk (floppies, that is; hard
> disks are a different story).

I'd love to get some info on that software,  particularly if I can ever get my 
hands on a DPU card to stick in there.

> Third-party software (e.g. CsCopy) can read/write MSDOS disks but requires
> Cromix+ (and a 680x0 CPU) which was the current Cromix version when the PC
> became commonplace.

Around the time I got that box I remember trying for some info and being told 
that the company wasn't doing anything but making 68K boxes for some 
specialized applications any more.

> Cromix+ and UNIX both read/write UNIX format disks; anything else that
> Cromix+ could handle was transferred to UNIX via a shared HD partition.

What's a "unix format disk"?

> Anything else would indeed require some custom programming; the FDC
> controller cards were reasonably well documented.

That's mostly what I was looking for,  if the common FDC chips back in those 
days were likely to be sufficient to handle a wide variety of "stuff" out 

> If the main CPU was a 680x0 instead of a Z80 then Z80 & CP/M software was
> run either on a dual (Z80/68000) DPU card or, if there was only a 680x0 CPU
> then it was run on the Z80 on an I/O card such as the IOP I/O processor or
> the Octart 8-port RS-232 card, if available.

I saw the sheet on the IOP in my book just now,  but don't know about that 
other one.  Why would they stick a processor on an 8-port serial card?

> Their first hard disks were 11MB 8" IMI drives using a WDI controller; they
> were superseded by 5 & 20 MB 5" IMI drives requiring a WDI-II. Then came
> MFM disks using an STDC controller and SMD drives & controller, and finally
> ESDI and SCSI drives using the ESDC controller.

Rigging up some sort of mounting hardware and finding 12V power for some of 
the 3.5" HDs I have kicking around here should be an interesting 
exercise.  :-)

I have nothing around for a controller,  but given the choice I'd rather go 
with SCSI if possible.

> The floppy controller also supported the small tape drives while the larger
> tapes required the ESDC controller, and there was also a controller and OS
> support for 9-track mag tape.


And then there's the Bigboard II,  which has this "SASI" port on it.  From 
what I was able to discover back when,  there didn't seem to be a whole heck 
of a lot of difference between that and SCSI at the hardware level as far as 
I could find out.  I also have a *very* vague recollection of some mod that 
somebody or other did that allowed the use of both sizes of floppy.  I guess 
that would'be had to involve selecting the data rate under software control 
instead of the switch or jumper that ordinarily set it (I don't recall which 
it was).

I don't know what might be needed to take advantage of the resemblance between 
SCSI and SASI and have no idea of where I might even start as far as the 
software is concerned.  Going to MFM I also did get a hold of a Xebec (?) 
board of some sort that would allow the interface,  but there's still the 
software issue to contend with and I don't even know what I have around any 
more for MFM drives.

I never got CP/M for that board at all,  deciding at the time I purchased it 
that it'd be better if I could spread the expense out a bit.  Then finding 
out that the company had shut down operations between me getting the hardware 
and trying for the software.  I'm open to suggestions as to how I might make 
a bootable disk that'll use the hardware that's there (DSDD) - -at this point 
it _will_ boot a Xerox 820 SSSD disk but that only gives me SSSD operatoin.  
And I'm not sure how to proceed from there.

The 'net is surprisingly short of any information on that board,  which is a 
shame because it's a damn nice board.

Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

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