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1.2MB floppy drive with 360kB controller...

cr1901

cr1901

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First off, thank you in advance Chuck(G) for answering this question (well, most likely) XD, but just like the question says... is it possible to use a 1.2MB floppy drive with a 360kB controller and 'fool' the controller into thinking its a 360kB drive (as long as I only put in 360kB floppies of course)?

Actually, since all drives have the same pinout/use the same encoding to send to the controller, why aren't they all universally interchangable? Hmmm...
 
Is it possible to set a 1.2MB floppy to 360K in a 286/386/486 and get it to work? And that's with a controller that understands a 1.2MB drive.
 
Stone said:
Is it possible to set a 1.2MB floppy to 360K in a 286/386/486 and get it to work? And that's with a controller that understands a 1.2MB drive.
Click to expand...

The controller I have doesn't 'understand' 1.2MB drives... I just want to substitute until I can find an 8-bit ISA floppy controller which can tolerate 1.2MB drives.
 
You need to beware... using a 1.2 as a 360k invites troubles, as the erase path on a 1.2 is narrower than the older 360...
READING 360 disks will not be an issue, but if you WRITE to them they will be unreadable in a NORMAL 360k drive...
Some of the original data WILL be missed by the narrower erase head and confusion will be the result.

If you don't intend to use them in a normal 360 again then you will (likely) be okay...

I HAVE been able to do the '1.2 as 360' in the BIOS before... but I had to ensure that I did not attempt to use HD disks...
:D
 
cr1901 said:
...Actually, since all drives have the same pinout/use the same encoding to send to the controller, why aren't they all universally interchangable? Hmmm...
Click to expand...
Well, because they spin at different speeds, the tracks are spaced differently, the heads are not the same width and they use different magnetic field strengths, for starters.

If you set the jumpers correctly you could probably read and write 360kB floppies, but they would in fact be 1/2 of a 720kB floppy and not compatible with anything except itself.

So, the answer is no, mainly because a single step of the 1.2 drive is only half the distance of a 360K step.
 
leeb said:
You need to beware... using a 1.2 as a 360k invites troubles, as the erase path on a 1.2 is narrower than the older 360...
READING 360 disks will not be an issue, but if you WRITE to them they will be unreadable in a NORMAL 360k drive...
Some of the original data WILL be missed by the narrower erase head and confusion will be the result.

If you don't intend to use them in a normal 360 again then you will (likely) be okay...

I HAVE been able to do the '1.2 as 360' in the BIOS before... but I had to ensure that I did not attempt to use HD disks...
:D
Click to expand...
With a 360kB DD controller???
 
AH... yes. Sorry, forgot about the double-step issue...

As I understood it, the idea was to use a 1.2 on a 360k controller, presumably to read/write(?) 360k disks...

... or am I confuzzed too?
 
leeb said:
As I understood it, the idea was to use a 1.2 on a 360k controller, presumably to read/write(?) 360k disks...
Click to expand...
^This. lol... I think I caused a chain reaction that blew a hole in the forums... :/
 
cr1901 said:
^This. lol... I think I caused a chain reaction that blew a hole in the forums... :/
Click to expand...
No confusion; to read/write a (standard) 360kB formatted disk in a (standard) 1.2MB HD drive the controller must be able to
a) send 2 step pulses for every step requested by the software
b) compensate for the different RPM by changing the data transfer rate
c) set the write current appropriately
- none of which a (standard) 360kB controller is capable of.
 
Some HD drives have jumpers that let the rotation rate be changed and automatically double step. I don't know if the result is close enough to an actual 360KB drive to transfer data with other 360KB drives.

There are probably other ways of writing a good enough 360KB diskette without using a proper 360KB drive. Anyone who knows of one, please share.
 
With some "1.2M" floppy drives, it is possible to set up "dual speed" (360/300 RPM) mode. so (b) above is taken care of.
(a) can be handled with an installable device driver, but that also means that you won't be able to boot from a 360K floppy
(c) is usually performed automatically on most modern drives--just leave pin 2 open.

Can you do it? Sure, but there are easier (and more satisfying) ways to torture yourself. Personally, I'd just install a 1.44MB 3.5" drive and run it in 720K mode. You can still put a 360K image on a 3.5" 720K floppy and boot from it. As a general rule, 720K floppies are quite reliable.
 
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Well, yes it is possible if you have a dual-speed jumper-selectable drive and a double-step driver; is such a driver available somewhere?

I was just trying to point out that despite having the same interface there are several differences among floppy drives that a high-density controller normally takes care of, so it's not quite as simple as just plugging it in as it is with a 1.2MB controller.
 
Oh, I probably have one somewhere in my bag of tricks... :)

Regardless, I wouldn't recommend using a 96 tpi drive in a 48 tpi application. It's just not good practice.
 
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