CROMIX

[r...@speakeasy.net]

Hi --

Anybody know of any documentation for the CROMIX file system structure?  What about device drivers for CROMIX?  I'm trying to understand the internals of CROMIX with an eye toward adapting it to hardware other than that for which it was intended.  I'm looking at CROMIX "L" right now, but maybe 68k CROMIX at some point?  I've got several compact flash devices that could serve as a "hard drive".  Maybe one of them would work in a modified CROMIX system?

I have everything needed to run CROMIX from floppy (and have it running), but no hard drive.

Are the chances slim to none?

Roger

 
 

[MikeS]

I don't know if it will help, but have a look at 023-4052, Modifying Cromix Drivers, available on Marcus' most excellent site. There are also similar manuals for Cromix+ (-5027) and UNIX (-5028) but I don't know if they're out there anywhere.

 

The Cromix manual gives a pretty good description of the higher level file system.

 

STDC controllers and compatible ST412/506 type hard disk drives are still reasonably available; WDI and WDI-II controllers are also available, but the compatible IMI drives are getting pretty scarce.

 

A solid state HD replacement would certainly be welcome, especially if it were compatible with the existing controllers; instead of modifying the drivers for the various versions of Cromix it might be easier to just accurately emulate the disk drive so it could be used with existing controllers and drivers, either IMI or ST506.

 

I think we'd all be interested...

 

mike

 

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[Marcus Bennett]

Roger,

This is just an approximate posting from memory, so others feel free to improve the accuracy ...

Many people has thought about running Cromix from a Flash based alternative to Hard drives and failed.   The source to the disk drivers and OS is not freely available and so the method I had wanted to use was a plug compatible ST506 disk.  This would attach to the STDC disk controller, and then Cromix would be none the wiser.

One or two horrendously expensive flash ST506 emulators exist.

On the Floppy front emulators exist, but the most hopeful which are plug compatible digital replacements for Asian Sewing machines that used floppies tend to replace a 5.25 360K disk or 720K 3.5 diskette and not th 1.2MB 8 inch 360 rpm floppy that would be great to run full Cromix from.   the 360 rpm emulation (detected by 64FDC et al) needs to be implemented and I ran out of patience ordering these emulator that come with no documentation and seeing if I could twiddle with them to get them to work.

For Character mode drivers in the Z80 sphere then Cromemco did publish some docs on howto create new IO drivers.

See my scan

http://maben.homeip.net/static/S100/cromemco/cromix/Cromemco%20Modifying%20a%20Cromix%20Driver%20023-4052%20198302.pdf

This was mainly I think to write a character mode driver on the slave IOP card and  I recall it was z80 assembler which I used really only on a test basis.

Anybody else care to comment?

regards marcus

[Brett Hunter]

Hi Marcus,

  I have used the HxC Floppy emulator (the SDcard version) to great effect on the Cromemco C-10.  It supports lots of retro computers, and I think it is supposed to support 8’’ drives as well. From the web site is says:

 

- Read / Write support
Track mode based floppy emulator (Full track pre-encoded in the HFE image file)
> Read support: Most of existing formats (FM/MFM/Amiga/E-mu track...) supported. Custom tracks supported.
> Write support: ISO MFM/DD 256/512/1024Bytes sector write supported.
> Write support: ISO FM /SD 128/256/512/1024Bytes sector write supported.
> Amiga Write support (Since the Rev.C Hardware)
> E-mu (Emulator I / II / SP1200) Write support (Since the Rev.C Hardware)

-RPM:
> 300 RPM , 360 RPM supported.
(others RPM possible).

- Floppy bitrate supported
>250/300Kbits/s (DD floppies)
>500Kbits/s (HD floppies) (others bitrates possible)
(Note : Variable bitrate not supported. So protected floppy disk image (IPF and STX file format) file support will be only partial !

 

 

I think I paid about $90 for it, so not cheap for retro use, but I have found it fantastic it copy to/from real disks and to use it as a real drive instead of old floppies.

 

Hope it helps

Brett

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[MikeS]

I don't see floppy emulation as a big issue, especially if a hard disk solution is found; as you and Brett point out, emulators presently exist (at least for 360K CDOS & CP/M diskettes) and since I do have hard disks in my systems I personally don't mind using floppies for testing or the occasional file transfer.

 

Regarding the hard disk issue I've always agreed that emulating the drive or the controller/drive combination at the hardware level would be much more feasible than modifying the drivers for all the various versions of Cromix and even CDOS, especially considering the lack of information.

 

A solid state more-or-less universal replacement for an ST-506 drive would certainly be welcome; considering that the commercial Datex units sell for around $2000 (on sale! ;-), it might even be a real money maker for someone. I'm really surprised that AFAIK no one has come up with one yet, although it's certainly been discussed a lot on the various forums and mail lists.

 

Another feasible solution might be a solid state replacement for the WDI-II/HD20 combination. Unfortunately the very latest versions of Cromix+ no longer support it, but for everything else (including CDOS) it might be simpler to implement and would not require a Cromemco controller card, and it is fairly well documented; maybe it'd be possible to add an embedded controller to the N8VEM S100 IDE controller, for example...

 

ESDI and SCSI are probably not really useful since only the very late Cromemco systems used them, and AFAIK SCSI was in fact only natively used for the tape drive.

 

Wish I had the time and the skills myself; compared to some of the impressive modern emulators and add-ons for some of the popular old computers (e.g. Apple, CBM, Atari etc.) it can't be THAT much more difficult...

 

mike