Heatkit 5 1/4 floppies

From: Richard Erlacher <edick_at_idcomm.com>
Date: Thu Apr 8 14:44:23 1999

Not all mini-floppy drives have the ability to load/unload the head. If
yours doesn't, it's advisable to fix the spin-up/spin-down problem with
either software or hardware, i.e. jumpers or the like. The decision to go
ahead and wear down the emulsion of your floppy diskette was made when
drives and media were common. That's no longer the case, and since you're
into retrocomputing, the slower(oops, I mean "more realistic") it is, the
better you'll like it, right??? The last time I checked (a long time ago)
my CP/M-ulator ran at 6-7x the speed of the "real McCoy" so I doubt you're
running the old hardware just to run those old programs.

While it's true that 8" drives can run constantly without media or head
damage they had head-load solenoids as opposed to a spring which loads the
heads once the drive door is closed as the mini-floppies often do. The
emulsion on a floppy diskette becomes increasingly abrasive as the emulsion
ages and, not only will it dirty the heads by leaving whatever dust or other
glutch is present on the diskette in the head gap, but it will polish and
grind on your heads. If you want your heads worn and dirty, running them in
constant contact with the media and spinning will do it just fine.

Dick

-----Original Message-----
From: Joe <rigdonj_at_intellistar.net>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Thursday, April 08, 1999 1:21 PM
Subject: Re: Heatkit 5 1/4 floppies


>Dick,
>
> I don't know if they're supposed to run all the time or not, but both
>drives do it so I don't think it's a problem in the drives. A lot of the
>older drives had jumpers to cause them to run continously. I guess it
>saved the time needed to spin the drive up to speed. Several people have
>said that they have systems with 5 1/4" drives that spin all the time so it
>may be normal. Allison says that her 8" drives have run thousands of hours
>without problems so I hope it's not a problem.
>
> Joe
>
>At 11:50 AM 4/8/99 -0600, you wrote:
>>8" drives typically spun all the time, as their motors were AC types. If
>>your 5-1/4" drive spins all the time, something's wrong. They had a
>>nMOTOR_ON signal which you can monitor to determine whether it's a
defective
>>drive or a bunged-up driver. One important reason for the popularity of
the
>>smaller drives over the AC-powered 8" types was noise. If the drive is
>>running all the time, clearly there's something wrong. It could be in the
>>jumpering of the drive or in the controller firmware. It could even be a
>>jumper option on the controller. You'll ruin lots of floppies in a drive
>>which doesn't stop and which doesn't unload its heads. It's easy to
monitor
>>the control signals. If the controller tells the disk drive to keep
>>spinning, you need to "fix" the BIOS code.
>>
>>Dick
>>-----Original Message-----
>>From: Joe <rigdonj_at_intellistar.net>
>>To: Discussion re-collecting of classic computers
>><classiccmp_at_u.washington.edu>
>>Date: Thursday, April 08, 1999 9:13 AM
>>Subject: Re: Heatkit 5 1/4 floppies
>>
>>
>>>At 09:43 PM 4/7/99 -0700, you wrote:
>>>
>>>People today don't realize that the old
>>>>systems used a floppy like present systems use a hard drive, almost all
>>the
>>>>time, which is a heck of a lot of wear for a contact media.
>>>
>>> I used to work for Burroughs and they had a computer that used 8"
>>>floppys that spun continously. Burroughs said to replace the disks every
>>>100 hours. I have no idea how long they would actually run before
failing.
>>> Does anyone know? I have a CPM machine that spins it's 5 1/4" disk
>>>continously but I haven't run it enough for a disk to fail.
>>>
>>> Joe
>>>>
>>>>
>>>
>>
>>
>
Received on Thu Apr 08 1999 - 14:44:23 BST