Cumana Dual 5 1/4 floppy drive

for bbc micro/electron hardware, peripherals & programming issues (NOT emulators!)
austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Cumana Dual 5 1/4 floppy drive

Post by austindan » Sun Dec 17, 2017 3:11 pm

Hi,

I have recently got hold of a Cumana dual 5 ¼ floppy disk drive. It is basically new in box and in amazing condition. It was used by the previous owner on a ti994a rather than a BBC.

When I hook the drive up to my BBC Master (DFS 1770), upon a *CAT, drive 0 spins but returns a Disk Error 18. In fact, both drives return the same error. I have tried a different disk drive cable and so I know the cable is OK. Could it be that the jumper settings on the drive need changing to match the BBC? I am pretty certain the drives are mechanically OK.

I have attached a photo of the current jumper settings. Any suggestions would be massively appreciated!
Dan.
Attachments
IMG_0162.jpg
IMG_0163.jpg

User avatar
MartinB
Posts: 4980
Joined: Mon Mar 31, 2008 9:04 pm
Location: Obscurity
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by MartinB » Sun Dec 17, 2017 6:58 pm

Could you find and post the drive mechanism model number on a label on the back of the drives? They're probably FD-1057 or similar but knowing might help us to validate the jumper settings.

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Sun Dec 17, 2017 9:47 pm

hi,
Thanks for the quick response. Both drives are NEC FD1055 drives.
Hope this helps - i am pretty certain its a jumper or 'little solder link' setting i need to change. Each drive does start to spin when i do a * CAT for drive 0 and 1 but doesn't return a catalogue.

User avatar
danielj
Posts: 6652
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by danielj » Sun Dec 17, 2017 9:57 pm

Have a looky here: http://ana-3.lcs.mit.edu/~jnc/cctalk/19 ... /2077.html

Code: Select all

NEC FD1055 5.25" HD/DD -- settings for BBC Micro 
DCG: 2 
USE: 2 
HDE: 2 
LUS: 1 Note LUS, MON, HS, LED : unclear which pins the labels refer to 
HS: 1 
LED: 1,5 
Does that help?

d.

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Mon Dec 18, 2017 1:58 pm

hi,
massive thanks for the jumper info. I applied all the jumper settings and alas no joy. Any other suggestions would be appreciated.
Thanks
Dan.

cmorley
Posts: 671
Joined: Sat Jul 30, 2016 7:11 pm
Location: Oxford
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by cmorley » Mon Dec 18, 2017 2:24 pm

Can you format a disk and read/verify that disk in the same drive?

Also, give the heads a good clean.

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Mon Dec 18, 2017 2:53 pm

hi,
I can't even format a disk :-(

I'll try cleaning the heads now.

User avatar
1024MAK
Posts: 8009
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by 1024MAK » Mon Dec 18, 2017 2:57 pm

A couple of things:
  • Check the connectors on the computer, the drive(s) and the cable(s). Are the pins clean and straight (not bent)?
  • Are the drives known to work with another computer?
  • Have the heads been cleaned?
  • What is the condition of the disk surface? Any signs of scoring, or discolouration (signs of the surface breaking up, or of mould)?
    Is your Beeb known to work with disk drives? Do you have another drive to try?
Mark

User avatar
1024MAK
Posts: 8009
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by 1024MAK » Mon Dec 18, 2017 2:59 pm

On the drives, one should be set to DS0 and the other to DS1 (or DS1 and DS2 if the numbering starts a 1 and not at zero). If they're both set the same, they may both transmit "data" to the computer on the same signal line at the same time :(

Mark

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Mon Dec 18, 2017 3:20 pm

Thanks for all the suggestions. The drives are brand new - no crud on the heads. Drives set to 0 and 1 respectively. BEEB works with other floppy drives. It's driving me nuts!

User avatar
danielj
Posts: 6652
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by danielj » Mon Dec 18, 2017 3:28 pm

One thing I note with old drives is the head sometimes get sticky - is it managing to move them successfully? Can you move them by hand (with power off)?

d.

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Mon Dec 18, 2017 3:32 pm

hi,
yes, i can move the head all the way 'up and down' the disk manually. If i leave it at the furthest point from track 0, it then correctly drives back to the start when i do a *CAT but then nothing...

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Mon Dec 18, 2017 3:38 pm

BOOM!!!!!!!

I figured it out (sort of). OK there was a little silver metal rectangular lid over each head. Once i removed them, the drives work PERFECTLY! Yeah ha! OK so now i need to understand what those little caps do?

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Mon Dec 18, 2017 3:40 pm

i think someone may have 'clamped' the little metal lids to the heads which was stopping the drive stepping through the disk. I think i'm going to leave the caps off - all seems to be working great!!!!!!!!

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Mon Dec 18, 2017 4:22 pm

OK a little more: both drives now *CAT perfectly but are a little intermittent in their ability to properly read disks. They seem to format disks in 40 and 80 track mode with no problems whatsoever. Do i need to perhaps re-align the heads? If so, does anyone have a good guide for doing this?

Also: does anyone know the purpose of the little metal rectangular cap that was stopping the drive head from working OK?
Thanks all,
Dan.

User avatar
1024MAK
Posts: 8009
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by 1024MAK » Mon Dec 18, 2017 4:48 pm

austindan wrote:BOOM!!!!!!!

I figured it out (sort of). OK there was a little silver metal rectangular lid over each head. Once i removed them, the drives work PERFECTLY! Yeah ha! OK so now i need to understand what those little caps do?
Put the "little silver metal rectangular lids" in a safe place (well away from the drives) such as the recycling bin!
The drives work fine without them. They would have originally been stuck on with either glue or double sided sticky pads.

Mark

User avatar
1024MAK
Posts: 8009
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by 1024MAK » Mon Dec 18, 2017 4:53 pm

If there is an alignment problem, that would not affect a drives ability to read a disk it has formatted and written to itself.

Disk drive alignment can be rather tricky, so best not to try until you are 100% certain. Also, you would really need a special alignment disk, but these are unattainable.

Mark

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Mon Dec 18, 2017 5:06 pm

hi Mark,
The drives are 100% fine formatting > saving > re-reading from their own format (in both 40T and 80T). The problem is with existing disks that work fine in my other machines that don't seem to work in the Cumana.
Cheers,
Dan.

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Mon Dec 18, 2017 10:18 pm

OK i'm closer but perhaps not...

It turns out, the 2 drives work perfectly when switched to 80 track mode. They can format, read, write from/to their own data. They can also read 80T disks that have been made on another BBC computer with an 80T drive. All 100% good when switched to 80T mode.

The problem is this: when i switch to 40T, the drive doesn't really switch to 40 track mode and so any read/write of course fails. What i need to figure out, is whether there is some sort of jumper/solder i need to make to enable the drive to behave as a 40/80 switchable drive. The physical 40/80 switch on the unit is giving a 5v and 0v reading when i toggle between 80 and 40T.

Does anyone know how to make this drive adhere to the physical 40/80T toggle?

Thanks!
Dan.

User avatar
1024MAK
Posts: 8009
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by 1024MAK » Mon Dec 18, 2017 11:06 pm

There is usually either an extra PCB with wires to the disk drives and some wires to the switch, or one of the boards of the disk drive has been modified.

Mark

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Tue Dec 19, 2017 2:16 pm

Thanks Mark,
As per the photo, there is already a physical 40/80T switch wired into the drive. When i toggle the switch i get a 0 and 5v reading across the 2 wires and so i know the switch is functioning OK. What i don't know though is how to configure the jumpers/solder links on the drive to make it actually work in switchable 40/80T mode. As mentioned, the drive(s) work perfectly in 80T mode.

If anyone has any ideas on this or perhaps has a Cumana drive that they can send me a photo of so that i can compare jumpers/solder links, i would hugely appreciate it. I feel like i am very close on this project...
Dan.

User avatar
danielj
Posts: 6652
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by danielj » Tue Dec 19, 2017 2:17 pm

I'll check my other cumana drive - the dual unit I have contains mitsubishi drives (I had a look yesterday evening)...

d.

austindan
Posts: 23
Joined: Fri Feb 03, 2017 9:35 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by austindan » Tue Dec 19, 2017 2:54 pm

Big thanks for checking. OK a little more progress: if i tell the BEEB that the drive is 40 track by typing "*drive 0 40", the drive works in 40T mode. I've never had to explicitly type this on other BBC machines - I've only ever had to change the physical drive switch on the drive.

I guess if this is the workaround, then i am more than happy to use the *drive 0 40 command when flipping the track switch on the drive.

Anyone else had to do this to get switchable drives to work?

Cheers,
Dan.

User avatar
danielj
Posts: 6652
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by danielj » Tue Dec 19, 2017 3:03 pm

Just leave it on 80 and the *DR. 0 40 will work. Looks like it's ignoring the switch for some reason.

Lots of people had 80 track only drives and used that method on the master.

d.

User avatar
1024MAK
Posts: 8009
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by 1024MAK » Tue Dec 19, 2017 3:30 pm

80 track drives can be made to read 40 track disks via these methods:-
  1. Software: the computer sends TWO step commands when moving track (that's what the command you are using does),
  2. Hardware: some extra electronics between the computer and the disk drive controller board, this generates an extra step command after the computer generates a step command, hence two steps,
  3. Hardware: with some disk drive controller boards, it has been found that the controller board can be "hacked" so that it steps the head twice instead of only once per step command,
  4. Hardware: it is also possible that some disk drives have a double step mode built in at the design stage.
Option 1 should work with all drives.

Your disk drives look like they are either 3 or 4.
If it is selected by a link, you'll need help from someone else with the same make and model of disk drives...

Mark

Coeus
Posts: 1080
Joined: Mon Jul 25, 2016 11:05 am
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by Coeus » Tue Dec 19, 2017 3:35 pm

danielj wrote:Just leave it on 80 and the *DR. 0 40 will work. Looks like it's ignoring the switch for some reason.

Lots of people had 80 track only drives and used that method on the master.

d.
And prior to the master some other DFSes also has a double-step feature which is essentially the same thing, i.e. the DFS sends two "step" commands to the controller each time it wants to step to a new track to compensate for the fact the head on an 80 track drive normally steps half as far as that on an 80 track drive.

On the question of compatibility, do bear in mind you may not have success in writing a disc on an 80 drive, and that includes a switchable one, for reading on a 40 track drive, particularly if the disc has been written to previously with a real 40 track drive. It is more likely to work if the drive is made to record the same signal on each of the two 80 track tracks that make up one 40 track track.

Really, the idea of switchable drives is to enable software distribution of 40 track discs on the basis that everyone can read them - an 80 drive double stepping should be fine with that,

User avatar
danielj
Posts: 6652
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by danielj » Tue Dec 19, 2017 3:42 pm

Indeed. I wouldn't bother trying to write 40 track discs with an 80 track drive.

d.

VincentVega
Posts: 295
Joined: Thu Sep 11, 2008 9:19 pm
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by VincentVega » Tue Dec 19, 2017 7:04 pm

I've got a Viglen dual floppy drive, also with a pair of NEC FD-1055s. Both drives have a circuit board hanging off the back that's connected to several points on the drive and to a toggle switch that allows you to change between 40 and 80 track mode. This worked fine on a Beeb with the older 8271 DFS and it could read and write 40 and 80 track floppies correctly.

The circuit consists of 74LS123 and a 74LS38 chips, together with a bunch of resistors and a pair of capacitors. One of my "never got around to finishing it" projects is to reproduce this as both boards are past their prime. The boards look like this:

Image
Image

The wires on the left of the second image go to the drive's PCB; the two on the right are for the toggle switch.

I can see if I can get the jumper positions for both drives if you want; the images I've included above were taken a while ago.

alienkidmj12
Posts: 48
Joined: Sat Aug 26, 2017 8:30 am
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by alienkidmj12 » Tue Jun 19, 2018 5:48 pm

austindan wrote:
Mon Dec 18, 2017 3:38 pm
BOOM!!!!!!!

I figured it out (sort of). OK there was a little silver metal rectangular lid over each head. Once i removed them, the drives work PERFECTLY! Yeah ha! OK so now i need to understand what those little caps do?
what is this clamp you talk of, i have the same drive , same issue

dave

User avatar
danielj
Posts: 6652
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester
Contact:

Re: Cumana Dual 5 1/4 floppy drive

Post by danielj » Tue Jun 19, 2018 7:27 pm

There's a metal plate attached to the drive head by a small piece of foam. The foam deteriorates and the head cover falls off and jams the mechanism. The covers add weight to the heads and it will perform better with them in place. You'll need to work out a replacement for the foam and re-fix ideally.

Post Reply