IBM Stared (*) 5 1/4" drives - What did it signify?

[Shadow Lord]

I just wanted to make sure on this: the star on the bezel simply signified whatever you wanted correct? i.e. it was not preset or always meant the same thing. I've usually taken it to mean "B" drive vs. "A" drive? But did it also signify a density (i.e. low vs. high density drive)?

 

[vwestlife]

I just wanted to make sure on this: the star on the bezel simply signified whatever you wanted correct? i.e. it was not preset or always meant the same thing. I've usually taken it to mean "B" drive vs. "A" drive? But did it also signify a density (i.e. low vs. high density drive)?

The star on the bezel indicated a 360K drive. Since they made 360K drives with both black and beige faceplates, the star gave you a way to differentiate a beige 360K drive from a beige 1.2M drive. (The black 360K drives, as used in the later XT and XT-286 with half-height drives, had the star as well.)

These floppy drives are also notable for the loud THUNK sound they make when the spindle motor turns on, and another loud CLICK when it shuts off. Therefore, copying a bunch of files is bound to result in a cacophany of THUNK ... CLICK - THUNK ... CLICK - THUNK ... CLICK...!

 

[SpidersWeb]

It was the marker to show which drive was 360KB

AT's had a 1.2Mb drive standard, and many came with a 360KB B-drive for backward compatibility. The * was to help people know which one was the low capacity drive.

Edit: vwestlife bet me to it

 

[Shadow Lord]

See, thats what I thought as well. Since i have two known 360KB drives w/ the star. However, I have one other system that came pre-installed w/ the black half height drives. One with the star one w/o. So I configured them as 1.2 and 360. Here is the strange part:

I formated a DSDD disk in the 360KB drive, took it to a DSHD drive, wrote to it, brought it back and it is being read perfectly fine. In fact a full disk was read back w/ no problem. I did this on four different floppies. I have never had any success in reading a DSDD disk in a low density drive after it being written to by a HD drive. In fact, taking the same disks that are being read in my HH LD drive and putting them in the 5150 FH drive produces an error (sector not found). I have to copy the files off, reformat in the LD HH drive, copy the files back on for the disk to work in my FH LD drive. Is this a fluke, a relatively common occurrence, or what?

The other strange thing is that the HD drive in the system will not read these disks. I guess this could be an alignment issue, but both drives will read and run programs on other disks.

I am a bit confused - mostly because I guess there I have no good way to guarantee one or more drives are not out of alignment. Therefore, any strange behavior makes me think the drive could be out of alignment.

 

[SpidersWeb]

It'll most likely be because you formatted it in the DD drive first and wrote to it with the HD drive.
It's only when you use a HD drive to write to a DD disk which has data written to it by a DD drive beforehand.

I'm not sure if it was an immediate/instant failure, I haven't tried recently, but the DD head is wider than the HD head.

 

[Shadow Lord]

It'll most likely be because you formatted it in the DD drive first and wrote to it with the HD drive.
It's only when you use a HD drive to write to a DD disk which has data written to it by a DD drive beforehand.

I'm not sure if it was an immediate/instant failure, I haven't tried recently, but the DD head is wider than the HD head.

So are you saying a blank DD disk shouldn't have read issues in a DD drive after being written to by a HD drive? I am not sure that is true as the narrower write width on the HD head should write in between the sectors and make the disk unreadable on a DD drive.

In either case though the HD drive shouldn't have problems reading the disks and it does.

I may have to take the drives out and see model numbers to double check but I believe the drives are YD-380 (HD) and YD-580 (DD) for the system in question.

 

[SpidersWeb]

When you ask a HD drive to write to a 360KB DD disk, it will double step. So it writes in the exact same places a DD drive would, BUT it writes a thinner track.
The problem occurs when the disk being used has had actual data written with a wider DD head, then the narrower HD head is only able to replace part of the track. So when it goes back in a DD drive later it can have issues being read.

I've often used a HD drive to make a 360KB boot disk (using DD media). I just make sure the disk is blank first. I wouldn't rely on it lasting forever but it works.

Not sure about the HD drive having read issues, part of me wonders about alignments and part of me wonders about write current + media differences and perhaps your HD drive is being picky - if it was a tiny bit off alignment that'd add to the situation as well, you end up with a thin weaker track on the disk which the head can only partially see. If it reads normal HD disks, then that's all good though.

Edit: just theories, someone back me up OR call me an idiot please

 

[Ole Juul]

In case it helps anyone clarify. Think of "track width" and "track spacing" as different things.

I've often used a HD drive to make a 360KB boot disk (using DD media). I just make sure the disk is blank first. I wouldn't rely on it lasting forever but it works.

Yep, that works just fine if you need a boot disk or one to make an image.

Edit: just theories, someone back me up OR call me an idiot please

I can't back you up other than to say that I hold much the same theories.

 

[Shadow Lord]

I see what you are saying. So if it is blank it may work and it may even work in a DD drive because the data is still written at the same starting "point" for a track. So theoretically a disk that is written in a HD drive that is practically full should be readable in a DD drive. It just maybe unstable.

I am not sure on the HD drive myself either. I think first order of business is a good run of drive cleaning and then seeing which drives are misbehaving. I don't know if it is an alignment issue because the HD drive has no issues reading disks made in other machines or manufactured (i.e. original SW) disks.

 

[krebizfan]

I see what you are saying. So if it is blank it may work and it may even work in a DD drive because the data is still written at the same starting "point" for a track. So theoretically a disk that is written in a HD drive that is practically full should be readable in a DD drive. It just maybe unstable.

I am not sure on the HD drive myself either. I think first order of business is a good run of drive cleaning and then seeing which drives are misbehaving. I don't know if it is an alignment issue because the HD drive has no issues reading disks made in other machines or manufactured (i.e. original SW) disks.

Not really ustable, I have 360KB floppies that I wrote with a 1.2 MB drive that still work more than 20 years later. However, the thinner track means that if a 360KB drive is slightly out of alignment, the 360KB drive won't find the track while still being perfectly fine with the thicker tracks laid down by other 360KB drives.

 

[barryp]

I have an IBM 4869, which is a standalone 360KB ALPS with the star, I think there's a DB-37 connector on it. I also have a few of the bare drives with the star. I don't have a model number in my files...