Cromix running on ZEMU emulator

[Oscar]

Hi,

Ever since I got a Cromemco System III in the mid 80s, I've wanted to experience Cromix. Something of a high point in Z80 development: multi-user, multi-tasking, all seriously functional on a Z80. Alas, I never got the Cromemco's hard drive to work and after some years, the PerSci 8 inch drives became tricky too.

So Cromix remained out of reach for almost 30 years... aww.

Maybe I'm just late finding this out, but there finally is an emulator which boots Cromix!
http://www.z80.info/zip/zemu.zip
http://www.z80.info/sample_disks/Cromemco.zip

Only thing that needed figuring out was that you need to select Disks->Tools and Options->Select Disk Clock Compare->Don't Care. And follow the Cromix.txt instructions. There it is! 3 terminal screens with a Cromix prompt!

Just in case there's others who care but didn't know either.

Cheers,

Oscar (now very busy going through the Cromix manuals I stored back in 1986).

 

[cluttered]

Just in case there's others who care but didn't know either.

I fit that description

I remember reading about Cromix many years ago and thinking it sounded amazing for a Z80 system, now I can finally experiment with it (albeit on an emulator). Thanks!

 

[MikeS]

Hi,

Ever since I got a Cromemco System III in the mid 80s, I've wanted to experience Cromix. Something of a high point in Z80 development: multi-user, multi-tasking, all seriously functional on a Z80. Alas, I never got the Cromemco's hard drive to work and after some years, the PerSci 8 inch drives became tricky too.

So Cromix remained out of reach for almost 30 years... aww.

Pshaw!
You can use up to four 1.2MB HD (or any combination of 360K & 1.2M) floppy drives instead of the PerScis, and hard drives and controllers are also out there (both WDI/IMI and STDC/ST412); as a matter of fact Z80 Cromix will install on two 360K drives (although you won't be able to do much with it ;-) )

But thanks for the heads-up; I'll have to check it out.

 

[retrogear]

If you haven't discovered it yet, check out this archive from Marcus Bennett. It's Cromemco and Cromix heaven !! Scroll down to find the numbered disk images themselves:

http://maben.homeip.net/static/S100/cromemco/code/disks/index.html

Larry

 

[Oscar]

You can use up to four 1.2MB HD (or any combination of 360K & 1.2M) floppy drives instead of the PerScis

True, but Cromix from floppies is not great. With Perscis, it was fast enough but on a much slower and smaller 5.25" floppy disk the fun was mostly gone, like you say, also because there's not much space left. At the time, I felt it was like smelling a really nice meal but being allowed to actually eat it... Or something like that.

hard drives and controllers are also out there (both WDI/IMI and STDC/ST412)

I'd be quite eager for an IMI drive but here in Europe I never found one - and getting one from the US makes me nervous about shipping damage & cost. I should probably get an STDC. But that means I've have to find yet another MFM drive (already need 3, they're the only things that die in my Nerd Room it seems).

But thanks for the heads-up; I'll have to check it out.

It's really nicely done - recommended.

Regards,

Oscar.

 

[MikeS]

True, but Cromix from floppies is not great. With Perscis, it was fast enough but on a much slower and smaller 5.25" floppy disk the fun was mostly gone, like you say, also because there's not much space left. At the time, I felt it was like smelling a really nice meal but being allowed to actually eat it... Or something like that.

Oh, I don't know... four 1.2MB drives would give you the same capacity as an HD-5 and it'd be interesting to compare the respective speeds; having four separately positioned heads might even be an advantage in some cases.

But Cromix doesn't really come into its own until you have Cromix+ running on the 680x0 XXU boards with fast STDC drives, 8MB RAM, IOP I/O coprocessors, etc. etc. ;-) Just had a couple of CS-420s stolen, alas, presumably for their scrap value :-(

Re ST412 drives: there's been considerable interest lately in building an ST-412/506 MFM drive emulator, but I suspect that Cromemco's 10KB sectors might be a problem...

 

[smplfyi]

Okay. I made an initial stab at using the ZEMU emulator.

In the initial run I just got CDOS going using ZEMU. I will post more as analysis continues.

http://majzel.blogspot.com/2014/02/running-cromemco-cdos-under-microsoft.html

In my excitement I'm having a Cromemco week and by Sunday I hope the real physical Cromemco systems (at least 2) will be up and spinning again.

It is a bit of an aside but

a) I'm going to revisit the Plug replacement Floppy emulators. I'm interested in a 1.2MB replacement 360rpm FM/MFM capable emulator at not ridiculous cost
Most of the cheap ones emulate 100 disks but not sure about everything else. And you will all remember that the Init program checks the RPM of the spinning floppy, so it must be within tolerance

b) After some more hours googling, [still] no joy on MFM solid state replacements , except again the really expensive (>1000 USD) units.

To concur with others: a Z80 simulation is quite remarkable in that it does manage to run CDOS and even the screen editor worked! However not sure about the Z80 cromix (how is banked memory supported?) & running from floppy is not optimal. And running 68K is where the systems really begin to shine.

To be continued!

Regards Marcus Bennett.

 

[MikeS]

In my excitement I'm having a Cromemco week and by Sunday I hope the real physical Cromemco systems (at least 2) will be up and spinning again.

Good Luck! Connect it to the 'Net and I'll log in via Telnet ;-)

a) I'm going to revisit the Plug replacement Floppy emulators. I'm interested in a 1.2MB replacement 360rpm FM/MFM capable emulator at not ridiculous cost

So am I; looks like the DECheads have got 'em working and I'm sure we can do anything they can do.

b) After some more hours googling, [still] no joy on MFM solid state replacements , except again the really expensive (>1000 USD) units.

As a matter of fact at least one design seems to be coming along pretty well so far, so there's hope; whether it'll handle Cromemco's 10KB sectors is another question...

To concur with others: a Z80 simulation is quite remarkable in that it does manage to run CDOS and even the screen editor worked

Incidentally there are patches and patched versions of Screen around that let you use a non-3101-compatible terminal; I think the help system is really the only place where a 3101 emulation is nice to have, and it's pretty well required for the HDTEST IMI drive test program.

However not sure about the Z80 cromix (how is banked memory supported?) & running from floppy is not optimal.

Certainly an interesting concept and fun to play with, especially if the emulation runs substantially faster, but

...running 68K is where the systems really begin to shine.

Well, IIRC 20-series on a DPU is actually slower than the Z80 11-series, but yes Cromix+ on an XXU (or even an XPU) is much more useful.

To be continued!

Look forward to it!

 

[Oscar]

Marcus,

However not sure about the Z80 cromix (how is banked memory supported?) & running from floppy is not optimal. And running 68K is where the systems really begin to shine.

ZEMU simulates 7 64KZ cards.

It's quite an, er, lovely emulator. Even the Cromemco terminal emulation seems flawless. Apparently ZEMU even allows you to switch the terminal connection to serial and even telnet ports. So I'm going to have a virtual Cromemco weekend, given that there's 800km between me and my physical Cromemco's. When I moved, I should have put them in the van with the rest of my meagre posessions. Now, it's hard to bring them over...

Mike,

But Cromix doesn't really come into its own until you have Cromix+ running on the 680x0 XXU boards with fast STDC drives, 8MB RAM, IOP I/O coprocessors, etc. etc. :wink: Just had a couple of CS-420s stolen, alas, presumably for their scrap value

Darn. Seems that your local thieves have no respect for occupational health & safety regulations. Stealing a Cromemco involves lifting it up - the relocation guys that I once asked for the same, refused on those grounds. Wimps. Maybe they should swap jobs with your band of thieves then.

Regards,

Oscar.

 

[TonHek]

Hi Oscar

It might be that I can help you with a IMI winchester for your Cromenco hardware. Yes, they are very rare.

I have an early Corvus systems rev C external HD, which spins up fine and goes ready. I have it in my possession since it was new.
In the cabinet is a IMI-5007 6MB (or 5 ?) 5,25 Disk. It has 26 pin connector (no not the later ST506/412).
Inside the cabinet is also a controller board, with z80 cpu, z80 pio's some eprom etc. On the edge of the board it shows: "Model 5000 controller". The other side of the controller has edge connector 120 pin? or something like that.
Outside the cabinet is 34 pin flatcable connector...
I can post some pictures if needed.

Cromenco compatible ?? I don't know. !! But for sure it's a 1981 IMI drive. (stamped inside the cabinet).

As I need space.. I'm willing to sell it.

Also I have found some Tandon Pack machines.. Maybe you recall, those had the ejectables "shock-proof" disks (but don't ever dare to drop them !!) 40MB, really slow steppers.
For those who might be interested.. Those are all MFM 40MB drives st-506/412. I have several available.

BTW, next week I will continue with your Suberbrain project again. Sorry, it takes some time due to some health set-back's.

Ton Hekstra
"AND-0FH" Hard/Software Solutions

 

[MikeS]

Hi Oscar

It might be that I can help you with a IMI winchester for your Cromenco hardware. Yes, they are very rare.

I have an early Corvus systems rev C external HD, which spins up fine and goes ready. I have it in my possession since it was new.
In the cabinet is a IMI-5007 6MB (or 5 ?) 5,25 Disk. It has 26 pin connector (no not the later ST506/412).

I think you will find that there is a 34-pin connector on the board closest to the drive; this would be the IMI interface that the Cromemco would want.

But I'd think that it would be more desirable to some people (and perhaps more valuable) as part of the Corvus package...

m

 

[TonHek]

IMI 5007 Corvus interface

IMI 5007 Corvus interface

I have included some pictures to clarify

I cannot find a 34 pin connector on the drive itself.. It's 26 pin.

So, might this be a "new" IMI drive interface.?

The controller in the cabinet is also IMI branded.


Ton Hekstra
"AND-0FH" Hard/Software Solutions

 

[IBM360MAN]

I hadn't heard of the Cromemco System 3, but it sounds really neat.

 

[new_castle_j]

In my excitement I'm having a Cromemco week and by Sunday I hope the real physical Cromemco systems (at least 2) will be up and spinning again.

A Cromemco week!?! That sounds fun, i'm feeling inspired to pull my Cromemco machine off the shelf. Can you advise me on what disks I would need to get this one running?

 

[MattisLind]

A Cromemco week!?! That sounds fun, i'm feeling inspired to pull my Cromemco machine off the shelf. Can you advise me on what disks I would need to get this one running?

Interesting coincidence! Last week I brought home a Cromemco System One chassis from storage and started to investigate it. It has a XPU card, two 1024KZ cards, one BIART, one OCTART, a STDC and finally a 64FDC card. When powering it up I was greeted by message and then I could press ESCAPE and get a prompt:

Preparing to boot, ESC to abort

Cromemco RDOS 03.08
;

Now I need to prepare some floppy disks. I am very curious if the hard drive works. It spins up, but if it is working is another matter. The drive is a IMI 5021H drive. I will try to make a image of the disk with David Gesswein's MFM emulator/reader.

 

[new_castle_j]

Interesting coincidence!

Nice website of your's by the way!

I just pulled mine off the shelf and took some inventory.
It has an inspection date of 4-8-85 and contains the following cards:
ZPU , 256KZ, STDC, TUART, 64FDC

I wasn't able to identify the model hard disk or floppy drive, would need to dismantle it some more. Very impressive chassis though, super compact and heavy duty. I have not tried powering on, will have to do some voltage checks first. If you are successful in imaging the hard disk, I'd like to know how you did it!

 

[MattisLind]

Nice website of your's by the way!

Thanks!

I wasn't able to identify the model hard disk or floppy drive, would need to dismantle it some more. Very impressive chassis though, super compact and heavy duty. I have not tried powering on, will have to do some voltage checks first.

There were some 4-5 screws on the bottom side that needed removal to get the floppy and hard disk loose. The PSU is very simple so it will probably work fine. I used a variac and all cards / drives removed just to be sure.

If you are successful in imaging the hard disk, I'd like to know how you did it!

Actually I did manage to image the drive. At least a raw dump using David's MFM emulator. But then to analyze that dump require some coding. I hope that David can help me out here. The format of the STDC is not yet supported by the analyzer software in the mfm emulator. There is only one 10240 bytes sector on each track! The track format is not near like any other controller, like WD, Xebec, Adaptec or OMTI as far as I can see.

I have put the images here if anyone likes to play around with them. I did several dumps just to be sure now when the drive was spinning. The drive was quite noisy so I am not sure how long it will survive.

 

[Al Kossow]

I have included some pictures to clarify

I cannot find a 34 pin connector on the drive itself.. It's 26 pin.

So, might this be a "new" IMI drive interface.?

The controller in the cabinet is also IMI branded.


Ton Hekstra
"AND-0FH" Hard/Software Solutions

The 26 pin connector is the "old" C drive interface.
What you are looking for is inside an H drive.

They were IMI 5012 or 5018. The 5007 is the original B series interface.
You can find brochures for the drives under http://bitsavers.org/pdf/imi/brochures

If what you need is a drive with a 20 and 34 pin interface, there are many models of ST412 compatible drives that should work
You can always ignore the extra heads/tracks of a larger drive.

 

[nigwil]

I also played around with Z80 Cromix via the emulator, impressive what a Z80 can be made to do:

http://i.imgur.com/XoX0Euw.jpg

 

[BubbaShakers]

I assume a lot of folks here already know about this, but for those that don't, you can also use Udo Monk's z80-pack emulator to run a turnkey Cromix setup, complete with a 3D model of a Z-1, blinkenlights and all. I've been using the virtual IMSAI in z80-pack for the last few months to develop and test a custom monitor for my (real) IMSAI. Cromemco support is a relatively recent addition (late 2014), and the very latest builds even have Dazzler emulation.