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Lazy 8" floppy disk question

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alan8086

Experienced Member
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Hi - Just a quickie regarding 8" disk compatibility


I'm after a sealed (and hopefully working) box of SSDD floppy disks. My IMS 8000 will go up to SSDD. Its system disk is SSDD but on reading the sysgen / IMSgen part of the manual, If I want to make a working copy of the system disk, it has to be SSDD. I have abundant SSSD 3M disks and no decent SSDD - I have dozens of old flaky disks that came with the machine but they are for archiving use only.

I have spotted on eBay a sealed pack of DSDD disks that could be worth a go - £40 inc postage.


Question is - would my SSDD Shugart SA800-1 and SSDD drive controller use DSDD disks Ok and just ignore the one side, or is it more involved than that? These disks would also work well for my NEC APC which has two DSDD drives.


I have been offered a pack of 10 DSDD disks in the past by a forum member, slightly lower price and a lot closer - I'm always a bit reluctant to dive into someone else's stash if I can possibly help myself out via eBay etc though.


Other thing - I have two boxes of 8" untested HARD SECTORED disks I have no use for. Is asking £40 a box for them too much/a miserable thing to do when I could just offer them here?! My goal is just to have enough cash to buy 10 disks for my IMS8000/NEC APC and one cheap HxC Gotek Chinese clone floppy drive emulator - then my floppy/imaging woes will be over!

Thanks for your opinions.
 
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That answers that then!

I've got lots of good SSSD disks - I need SSDD disks to make a working system disk however - unless i'm reading the manual wrong?

I am still getting odd behaviour when formatting floppies, movcpm/sysgen'ing a sssd disk always ends in an odd failure. Part of the issue was defective RAM chips -I've tested all 128 of the 2114 chips and replaced maybe 11 of them. After that I haven't seen any more Parity Errors and was able to format a SSSD disk in the B: drive - once. Still cant movcpm or sysgen to create a working system disk however. I've tried SSSD disks and a few SSDD disks that at least look good visually but it wont touch SSDD disks. Says 'Drive Not Ready'


I wanted a box of SSDD disks that I know are good (sealed, NOS etc) to eliminate more nonsense from the list of possible issues.
 
Al Kossow said:
nope, the index hole is in the wrong place

a good brand of sssd disks should work dd
Click to expand...

- Sorry I just re read your message - So my IMS 8000 system should work just as well if I con it into thinking the SSSD 3M disks I have are double density? For example - during format - tell it I have DD disk inserted even though its a Single density?

Hmm - that would make things easier. However, I'm pretty sure when I try and movcpm from the DD system disk to a SD blank disk, it detects that it has a SD disk inserted.

I'll keep fiddling with it!
 
alan8086 said:
- Sorry I just re read your message - So my IMS 8000 system should work just as well if I con it into thinking the SSSD 3M disks I have are double density?
Click to expand...

Yes, there is no physical difference between late single sided SD and DD.
The big thing that changed was vendors polishing the surface of disks (I think Dysan was the first company to do that)

If you have a bulk tape eraser, you could try erasing the surface before formatting to guarantee the system thinks the disk is blank before attempting a DD format.
The other thing would be finding a utility that formats and verifies DD sectors at the same time.
 
alan8086 said:
That answers that then!

I've got lots of good SSSD disks - I need SSDD disks to make a working system disk however - unless i'm reading the manual wrong?

I am still getting odd behaviour when formatting floppies, movcpm/sysgen'ing a sssd disk always ends in an odd failure. Part of the issue was defective RAM chips -I've tested all 128 of the 2114 chips and replaced maybe 11 of them. After that I haven't seen any more Parity Errors and was able to format a SSSD disk in the B: drive - once. Still cant movcpm or sysgen to create a working system disk however. I've tried SSSD disks and a few SSDD disks that at least look good visually but it wont touch SSDD disks. Says 'Drive Not Ready'


I wanted a box of SSDD disks that I know are good (sealed, NOS etc) to eliminate more nonsense from the list of possible issues.
Click to expand...


Unfortunately, sealed or NOS is no guarantee they are still good either. Although it is better than used, so... :)

I would rather ask if someone can format/test one for you first, as that would eliminate it.
 
Al Kossow said:
Yes, there is no physical difference between late single sided SD and DD.
The big thing that changed was vendors polishing the surface of disks (I think Dysan was the first company to do that)

If you have a bulk tape eraser, you could try erasing the surface before formatting to guarantee the system thinks the disk is blank before attempting a DD format.
The other thing would be finding a utility that formats and verifies DD sectors at the same time.
Click to expand...

'Bulk Tape Eraser' - sounds like a big magnet?! Would Dave Dunfields IMD software do something similar? It has Erase and Format functionality, although I've used it to format in SSSD in the past and the IMS 8000 still see's it as a blank disk.

Oh - the SSSD 3M disk surface is very shiny! I had come to take that as a sign of 'goodness'!! I now know better, so thanks for that.
 
I don't know if this would be any help at all, but...

I've got a pack of 8" disks but no drive for them, although I've long hoped to 'find' an 8" drive and get them working.

The disks are marked CD Control Data (which I assume to be a hardware mfg, not the maker of the disks).

The label on each says

1225-60
Double Side
Double Density
Record Length
256 bytes
26 sectors

Which I would assume means that the disks are ready formatted for a specific machine?

The disks are NOS, unused/unmarked, but not sealed. There is one index hole, so they're soft sector.

I would really like to keep some, but I'm sure I'll never need ALL 10.

On the general point, a SS drive should not have any problem formatting a DS disk. I've never had any SD disks to check, but I'd not expect any problems with a SD drive using a DD disk, although I might worry about a DD drive using a SD disk. As another poster suggests above, this is less likely a problem with later production, as I very much doubt that the manufacturers distinguished between production runs, although they might have had different testing/verification processes.

Geoff
 
The usual way for manufacturers to ship preformatted disks in 8" was either SSSD 26/128 (IBM 3740) or DSDD 26/256 (IBM System/3) format. There are certainly other IBM formats, but those were the most common. Remember that not all old gear using 8" disks could low-level format them.
 
8-inch (soft sectored) diskettes are physically either single-sided, or double-sided. The difference is NOT in the rotating media inside the sleeve; the difference is in the location of the index-hole in the SLEEVE. The sleeve's index hole is at a different location (rotary angle) for SS versus DS. But the rotating media (the cookie with the magnetic coating) is almost always the same for both; coated on both sides. And the magnetic coating is the same for single-density and double-density. So you can reformat between single-density and double-density (with controllers that can do that). Drives are NOT "single or double density"; they are single or double sided (one head or two heads).

Why doesn't matter much. But a 8" double sided drive, can 'tell" immediately if a diskette is single sided or double sided. Then it knows where the track starts (relative to the rotary angle of the rotating media). And an 8" single-sided drive, cannot operate a double-sided diskette (and goof up half the diskette).

Regarding "bulk erasers". Look up "bulk audio tape erasers". From the era of audio tape. They are good for scrubbing diskettes too. - Herb
 
Somewhere on this forum I detailed a pretty good floppy eraser that uses magnets from a discarded magnetron (think microwave oven). Seems to render disks that I've tried it with completely unreadable. It's a little tricky to assemble unless you've got some good clamps, as the magnets are assembled with like poles facing separated by perhaps 1/8".
 
Chuck(G) said:
Somewhere on this forum I detailed a pretty good floppy eraser that uses magnets from a discarded magnetron (think microwave oven). Seems to render disks that I've tried it with completely unreadable. It's a little tricky to assemble unless you've got some good clamps, as the magnets are assembled with like poles facing separated by perhaps 1/8".
Click to expand...

I've been known to wrap a few layers of paper around a supper magnet and place the disk against the refrigerator ( assuming it has a steel door ). I drag the magnet around
the disk. If it is too hard to move, add layers of paper.
While for audio tape, it is best to not use a single polarity bias, digital media is always erased with a single direction of bias so it is not an issue for disk.
Dwight
 
Info regarding position of index hole noted. Thanks. The hole on the disks I have is roughly at a 1:00 position looking at the front of the disk. What's the position for a SS disk, maybe 11:00? I'm sure the hole for the head(s) is standard at 6:00.

Geoff
 
Dwight Elvey said:
While for audio tape, it is best to not use a single polarity bias, digital media is always erased with a single direction of bias so it is not an issue for disk.
Click to expand...

Digital media is always recorded at saturation levels, so bias hardly matters; i.e. you're working at the tip of the magnetization curve. Analog media employs the most linear (in theory) portion of the curve, so bias matters.

As far as index hole positions, look at PDF page 11 here

As an aside, note that the original IBM 8" diskettes looked like this:

IBMdiskette8.gif
 
If you don't have a bulk eraser, and don't want to get one, just format the disk a few times if the first time fails. It's at least not like HD vs DD drives in the 5.25" world -- the track width and coercivity is the same.

You can hole-punch a new index hole opening in the correct place to turn double-sided media into single-sided, or the other way around. You should put a sticker over the index hole you're not using. I've also got some 8" single-sided disks with two index holes, so they can be used as "flippy" disks.
 
Make sure to put a small piece of thin cardboard between the punch and the media. You need to protect the disk from the back side of the punch. I usually use a cereal box. I cut a strip that will fit through the head window opening.
Dwight
 
That's a very kind offer Geoff!

You must 'find' some 8" drives - they really are a sight in operation!

However - I think I've got to the stage where I have realised I still have hardware issues - yesterday I managed to 'copy all' the diagnostics disk that came with the IMS8000 to my one successfully formatted disk. I watched with glee as the drives copied a sector at a time - the head load solenoids clacking away every second or so with increasing duration, the further toward the disk centre they got! I don't watch television but I could have watched that over and over!! However - I still cant format disks!


GeoffB17 said:
I don't know if this would be any help at all, but...

I've got a pack of 8" disks but no drive for them, although I've long hoped to 'find' an 8" drive and get them working.

The disks are marked CD Control Data (which I assume to be a hardware mfg, not the maker of the disks).

The label on each says

1225-60
Double Side
Double Density
Record Length
256 bytes
26 sectors

Which I would assume means that the disks are ready formatted for a specific machine?

The disks are NOS, unused/unmarked, but not sealed. There is one index hole, so they're soft sector.

I would really like to keep some, but I'm sure I'll never need ALL 10.

On the general point, a SS drive should not have any problem formatting a DS disk. I've never had any SD disks to check, but I'd not expect any problems with a SD drive using a DD disk, although I might worry about a DD drive using a SD disk. As another poster suggests above, this is less likely a problem with later production, as I very much doubt that the manufacturers distinguished between production runs, although they might have had different testing/verification processes.

Geoff
Click to expand...
 
Hello Herb - I've been on and off your venerable website for all the years I've been into old computers - I'm glad it's still up and running! I read the IMS5000 saga from the guy in Australia, very interesting.

It IS interesting why manufacturers could go from SSSD to DSDD without needing to change the rotating media itself - I wont ask why however...

All the bulk tape erasor devices I see on eBay are on your side of the Atlantic we're a fairly boring lot over here! As suggested in another reply, I'll look out for an old Magnatron - being careful of the Beryllium Oxide spacer - and try and make a home brew disk eraser.

hjohnson said:
8-inch (soft sectored) diskettes are physically either single-sided, or double-sided. The difference is NOT in the rotating media inside the sleeve; the difference is in the location of the index-hole in the SLEEVE. The sleeve's index hole is at a different location (rotary angle) for SS versus DS. But the rotating media (the cookie with the magnetic coating) is almost always the same for both; coated on both sides. And the magnetic coating is the same for single-density and double-density. So you can reformat between single-density and double-density (with controllers that can do that). Drives are NOT "single or double density"; they are single or double sided (one head or two heads).

Why doesn't matter much. But a 8" double sided drive, can 'tell" immediately if a diskette is single sided or double sided. Then it knows where the track starts (relative to the rotary angle of the rotating media). And an 8" single-sided drive, cannot operate a double-sided diskette (and goof up half the diskette).

Regarding "bulk erasers". Look up "bulk audio tape erasers". From the era of audio tape. They are good for scrubbing diskettes too. - Herb
Click to expand...
 
Thanks for your suggestion - I can only format disks using Dave Dunfields IMD software and my Pentium 133 Imaging rig. I cant yet format out of CP/M on the IMS8000 although things started going in the right direction once I realised the HL jumper was missing on the A drive - it had been bashed off in decades passed. All the time I've had this machine, The A: drive would'nt activate the HL solenoid - I assumed some logic fault or one of the power transistors on the SA800-2 logic board. I've always had the A: and B: drives swapped until recently.


A couple of weeks ago I realised this HL jumper was missing (its present and jumpered on the B: drive), replaced it and now it reads and in certain circumstances, writes to floppies.
I have A: and B: drives in their original positions now (with device no jumpered correctly) If I try to format on either drive, on selecting single density - the drive seems to get to the first sector, then the computer locks up and needs a hard reset. It locks up instantly with Double Density selected.

I do have RAM issues in the background - I ordered 15 2114 RAM chips off Jameco a few weeks back and have been testing all 128 chips in my ABI tester (which broke yesterday - my repair is detailed in the 'Tools' section) Initially I found 2 dead RAM chips, replacing them is what bought the machine back to a boot prompt after years of storage. Testing again and replacing a couple more chips and I was able to read disks without any Parity Errors - plus working out the correct jumper settings on the drives.

I am still getting Parity Errors when trying to movcpm and sysgen from the system floppy to a new floppy - plus the issues I have trying to format a floppy - which I have only successfully done once.

Anyhow - I need to work out these hardware issues before deciding bad floppies is the issue - certainly if SSSD disk (which I have many of) are just as good as SSDD, I don't have many issues there.


glitch said:
If you don't have a bulk eraser, and don't want to get one, just format the disk a few times if the first time fails. It's at least not like HD vs DD drives in the 5.25" world -- the track width and coercivity is the same.

You can hole-punch a new index hole opening in the correct place to turn double-sided media into single-sided, or the other way around. You should put a sticker over the index hole you're not using. I've also got some 8" single-sided disks with two index holes, so they can be used as "flippy" disks.
Click to expand...
 
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