Jumper 300 on 3,5 floppy drives - what use?

[pgru2]

Hi and thank You for reply in advance
I have an YD-701B-6031B floppy drive(sadly no manual for it, if You have a manual/service please share) - and according to similar drives manual on Internet I guess that jumper 300 is not the speed of the drive(like in case of 5,25 probably) but it is the speed of data transmission. As it is a HD 3,5 floppy drive I am trying to find/know more:
1) Does this mean that e.g. in case of reading HD floppy disks it will lower to 300 instead of 500?
2) If yes - would it work(e.g. read HD floppies) with some "vintage" controllers - like that in Amiga, or even first used in IBM 5150/similar?

 

[krebizfan]

The only case I can think of where 300 would apply to transmission rate would be the 300 kbps mode used by 1.2 MB drives to read/write double density (360/720k) disks. I haven't seen such with a 3.5" drive but the references I have suggest that the first 3.5" high density drives were designed around the same 360 RPM and 1.2 MB mode as the 5.25" high density drives.

YD-700 seems to be a dual speed (360 and 300 RPM) drive that supports the 1.2 MB format not the 1.44 MB. YD-701 and YD-702 can use the 1.44 MB format but the manuals on Bitsavers are all for the 702 model which doesn't do the 1.2 MB mode. 701 seems to be PS/2 model which flips the density pin from the AT signal. Some of the 701 and 702 models have to be the 3 mode drives which I know YE Data was selling.

Does the drive work with standard 1.44 MB and 720K disks when used with a standard controller?

 

[Chuck(G)]

PC98 systems carry the 1.3MB format (8x1024) across the entire family of floppies, from 8" to 3.5". That is, the format is constant no matter the physical drive size. For this to work, the spindle speed is the same; namely 360 RPM. This is the reason for the "3 mode" settings you sometimes see in BIOS setup - 1.44, 1.23 and 720 for motherboards that support this.

It's more common than you'd think. For example, Mitsubishi/Mazak PLCs equipped with 3.5" drive support use the PC98 standard.

Take a look at the datasheet for the Samsung SFD-321B drive--note the jumper options for 1MB, 1.6MB and 2MB (unformatted) operation.

 

[krebizfan]

More important to the OP's questions, the drive that would allow the use of high density 3.5" disks with a double density controller would need to rotate at 150 RPM. The small number of drives that can do that are listed at various Amiga affiliated sites but this YE Data drive is not one of them.

 

[Chuck(G)]

In any case, having a drive rotate at half-speed is a lousy idea, even if somewhat workable. Weltec in the 1980s introduced a 5.25" 96 tpi floppy drive that could be programmed to spin at 300 RPM as well as 180 RPM. The idea was that you could read 5.25" 720 and 360 floppies and read/write 1.2M using the original 5150/60 FDC. It was fraught with problems, was expensive and never got past the trial balloon stage, as far as I know.

One of the problems is that the induced EMF in a read head is directly proportional to the linear speed of the medium. Slower speed = less signal. I've long suspected that was the reason that the first Sony 3.5" drives spun at 600 RPM.

 

[krebizfan]

The 3.5" drive that downshifted to 150 RPM when handling high density disks is the Chinon FZ-357A. Worked with the Amiga's floppy controller. I don't know if anyone ever tried it with a double density PC controller. By the time it arrived, getting an 8-bit high density floppy controller was an easy and cheap option for any XT compatible.

 

[pgru2]

Thanks for replies.

About this drive - it was working more than 15 years ago in my Compaq Prolinea(486 class), but as a DD drive ~720KB. It is more than possible, that I just don't switched in Compaq BIOS it correctly, but Compaq worked with cheap (probably less than 4$ then, "no jumper", but need to check it 3,5 drive) as a HD drive. Drive itself is probably HD - not only jumpers, but have 2 sensors, on other sides. It is probably - the 3-mode drive, because it have an IF switch(according to other TEAC manuals).

Sadly I still don't known for what is P1 and JP12...

According to Wikipedia Amiga can read up to 500 in DD mode, and 250 in GCR/SD mode. The technical limitation is write speed - it must be probably 500 or 250 exactly. But Amiga can read with other - it was probably used as a "lock" because same games were trying to read data, measure time and if it was written with 500 or 250 it was a problem, because game should have this data written at different speed that Amiga can? What do You think about this?

 

[krebizfan]

You may want to try to clean the high density sensor. This drive should be able to write high density disks.

Check with a more game oriented Amiga forum. I have never heard of an Amiga using 300 kbps mode for anything.

The JP is just the marker for the block of jumpers. P1 isn't listed in any manual I have found. If it matters, you could try following the traces from the jumper to whatever it connects to. Maybe that could provide a clue for its use.