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Any Cromemco owners/users out there?

Druid6900

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A lot of old 8" drives, such as the SA800, used to have either a dip shunt or a set of staking pins on the drive logic board (usually near the connector) that designated what drive the unit was.

If you can find these, and change them one for the other, your operational drive would then become your first drive and vice versa.
 

billdeg

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hmmm...maybe. Fortunately I have all of the documentation so I can diagnose what's what.

By weird coincidence, the class I am teaching Monday is about early disk drives, and we go into the PerSci drives a little.

The best next thing to do is carefully take pull out the drives and re-seat the drive controller chips and cables. Because this system was sitting in a temperature-controlled room, cabled up and ready to go since 1979, the connections may simply need a little giggling to restore full function. I don't think I need to make any dip switch changes, etc.

You have to have seen the house that this system came from...there was a room essentially dedicated to the System Three, and old books. Imagine "walking into 1979" - the view from the computer room was a window overlooking about 20 acres of woods; a really nice computer room.
 

MikeS

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Well, I'd say the best next thing would be to be able to talk to RDOS ;-)
It'd be nice to be able to talk to the computer and verify that it's actually working (and that you have a good boot disk) before you start making changes to the configuration.

AFAIR assigning drive sequence is not quite the same as a "normal" Shugart or Tandon, but you've got the manual and in any case it would just require swapping the DS settings and drive locations.

Bill, I assume you got my phone # OK just in case?
 

billdeg

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Thanks Mike for your help.

Here is an update:
RDOS works now. It probably always did, but the terminal was bad.
The Hazletine 1510 is stuck in local mode, I need to fix. I replaced with my trusty Zenith Z-19. I ran some memory dumps, and other RDOS monitor commands, seems perfectly functional.

There is nothing in the RDOS manual about changing the boot drive to B (PerSci dual drive), using a 4FDC with RDOS 1.1. There may be a hardware solution. If I find one, then I can bypass the bad A drive and boot with the B drive. At least I'd have one drive to play with.

I plan to remove the dual drive to see if there is a mechanical problem. The system definitely tries to boot from A, but the drive does not respond fully. The drive A light comes on and then the system hangs, RDOS hangs. If I am patient and careful, I can usually shake the drive loose.

I will keep you all posted.

Bill
 

chuckcmagee

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Diddo here! I have a 4FDC controller that works fine. I don't own any 8" drives so my first drive would be "C:". I too haven't figured out how to get it to try and boot from a different drive. I really don't want to get started with the 8" drives again. The 5.25 ones are enough of a pain, as it is. I thought I might have to come up with some kind of 8" terminator cable but haven't pursued that line of attack yet.
 

MikeS

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Well, unlike later versions of RDOS it does look like the 4FDC version only boots from drive A.

But Chuck, are you sure about that drive C? Seems to me if you set the 5" drive jumper to A it should boot from that, no problem; it usually reads the drive type off the disk itself unless it's an IBM standard 8". The System 3 was the only one that had 8" disks (except for third-party stuff) so even the old 4FDC would have to be able to boot from a 5" floppy. Mind you, you'd probably have to gen a new version of CDOS.
Then again, I didn't do much with 4FDCs "in my day" other then scrap a few (and the systems they were in), so what do I know; 16FDCs could certainly boot from any drive and any size FWIW...

What kind of box i.e. which model have you got there?
 
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MikeS

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Chuck:

There's also the option of using 5 1/4" HD drives instead of the 8" drives; to the controller they're identical. Depending on the drive you'll probably have to change some jumpers and either install some jumpers on the FDC or make a custom cable to connect it to the 50-pin interface; a cheap and dirty way of tripling disk capacity in a 5" box or just replacing the 8" drives & disks with 5 1/4.

Of course you'll need an 8" drive initially (or 8" images) for the one-time conversion of your 8" disks.
 

billdeg

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From cctalk, re: PerSci Drives

From cctalk, re: PerSci Drives

I got a couple of replies from cctalk, not sure if they are accurate, but..here is a summary of what I was told:

"... it appears that they use incandescent (!) bulbs for things like index pulse, etc. in those drives. "

"Disk detection on the Persci 270 series drives (and I think on the 299
series drives as well) is simply a microswitch triggered by the leading edge
of the diskette.

There are NO electronics in the insert detection / clamp / eject mechanism.
It is a trivial circuit consisting ONLY of a DC electric motor (24 volts, I
think) and 4 microswitches (two of these are operated by cams on the motor
shaft, one is the front panel eject switch and one is triggered by the
diskette itself when it's pushed in). All you need to troubleshoot it is a
multimeter. It has no connection to the actual "electronics" of the drive.
It's just straight DC electricity. Schematics are available on the Harte
site and in other places if you don't have the manuals.

The only thing different about the CS3 implementation is that they removed
the front bezel of the drives, and then replaced the eject switches that had
been part of the drive's own front bezel (now removed) with a switch on the
CS3 chassis. I don't remember if they connected this through the switch
wires left over from the (removed) Persci front bezel or if they did eject
through the 50-pin data interface connector (Persci did allow an eject
function through the 50-pin data cable)."
 

amouse

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Bill,

A warm welcome to the cromemco community .

You need to get some initial life from your system so I would suggest
a) install minimum == cards floppy controller (4FDC), CPU (ZPU) and memory (64Kz)
b) Memory card configured so upon power up there is a hole in upper memory config to allow for BIOS on 4FDC which is at C000
c) ZPU has speed switch 2 or 4MHz so either should work
d) Serial cable from 4FDC serial port to an ascii terminal with no RS232 handshaking
e) Switches on the 4FDC to NOT select a baud rate
f) suggest connected ASCII terminal at 9600 baud

Upon power on ZPU should jump to C000 and upon you hitting enter a few times figure out the 9600 baud and print out an RDOS message

You say you have the manuals but if any are missing try my wesbite cards section

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

let me know how you are getting on
 

MikeS

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Well, hello there; fancy meeting you here!

I've talked to Bill and last I heard he had RDOS running but was having trouble with the left PerSci (A & B). Am I correct in my understanding that RDOS 1.x as used on the 4FDC can only boot from drive A, and that he'll have to swap drives (or at least the DS jumper blocks)? I only have experience with 16 & 64FDC and RDOS 2 & 3.

mike
 

billdeg

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I have a modified 16FDC card from another system. I also have a TU ART card to play with. If I can't repair the PerSci, I will try to return the 16FDC back to "stock" and then use it to assign B as the boot drive, if that's possible. Anyone know for sure that this can be done? I don't have a copy of the 16FDC manual, but I am sure that it's easy to obtain online.

I have brought the whole system downstairs into my work area, and re-assembled the desk and installed the computer into the desk. I will put up pictures of the assembled system. Post 15 of this thread contains a link to the original pics I took, while the system was still in my living room.

Bill
 

MikeS

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Hi Bill:

I would still recommend swapping drives or at least the Drive Select jumper blocks; if the 16FDC has been modified you're just adding another possible problem.

However, yes, the 16FDC with RDOS >=2.50 uses DIP switches 7 & 8 to determine the boot drive and you can also select it manually (Bx, where x=A to D); however, your CDOS should be version 2.45 or greater (and Cromix >= version 11.08 ).

You won't find this in the 16FDC manual AFAIK because it's a function of RDOS, and the relevant versions were released after the manual was printed.

Good luck!

m
 
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1980s_john

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Z-2D here

Z-2D here

Hi,

I've got a Z-2D: http://www.vintagecomputers.btinternet.co.uk/cpm/cromemco.htm

Big beast, works fine (once the old floppy drive was replaced). I have a CDOS boot disk (courtesy of a very kind UK collector), for my 4FDC based system.

I am looking for a CP/M boot disk for this set up, Dave Dunfield has an image on his site for a 16FDC based system. I know I ought to be be able to create one from scratch (starting from BDOS), but this is easier said than done and I much prefer to make / receive copies of boot disks rather than do it the hard way.

Regards,
John
 

MikeS

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Nice box, the Z-2; scrapped a couple 'cause they were kind of big and power hungry, but have regretted it a few times.

Have you actually tried Dave's image? I think it might well work with a 4FDC, but your problem would probably be the 8" format, although there are ways around that. There are others around as well, but they're 8" as well and may in fact be the same disk.

What's wrong with using CDOS? It's essentially a modified clone of CP/M after all.

m
 

billdeg

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Update - I have swapped out the 4FDC and replaced with the 16FDC. With the added capability (more jumpers and RDOS upgrade) I can get the system to boot to the good B drive. Unfortunately the system software almost immediately re-directs to read from the A drive. Fair enough, at least I got a little farther.

I have some excellent info on PerSci repair. I continue to close in on a complete restoration and will work to fix the drive.

Of note: If you flash a bright light on the drive, you can get it to "eject" the disk even if there's none in the drive. Conversely you can trick it into thinking there's a disk in the drive when there really is not. I found this out by accident!

Bd
 

MikeS

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Boy, you really don't want to swap those jumpers and bring it up on the second drive, do ya...

Alternately, you could disconnect the 8" drives and temporarily hook up a 5 1/4HD drive as drive A; needs a jumper from pin 34 to pin 22 (?) on the 50 pin connector.

Your CDOS is probably not new enough to run on B. Try a later version.

m
 

amouse

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Well strangely enough I have noticed that old versions of CDOS ... not only dont seem to support doubled sided and double density very clearly but also on booting head over to the A: drive.

In fact it will boot from B: completely then you would see the A: drive light power on.

Although you will find my versions of Cromemco CDOS on the web at this address

http://maben.homeip.net/static/S100/cromemco/code/operating systems/DOS CDOS/index.html

It might be kind of difficult for you to get them from your Web / PC onto the cromemco system. (Er a whole disasterously large topic we could go on and on about). So if you contact me offline I suppose I could post you something from Swizerland if you got desperate!

regards marcus.
 

billdeg

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I simply followed the directions in the manual for boot drive assignment, very easy. jumper switch 7 and 8 are used for this purpose, just like how one would assign a drive number to a Commdore 1571.

BTW CDOS 2.52 is the version I have.
 
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