[sdiy] Atari disk drive

[Hallvard Tangeraas]

At 19:53 +0100  29-11-01, Andre Majorel wrote:


> On 2001-11-29 07:05 -0800, Jim Patchell wrote:
>
>> trouble
>> is, my Atari is getting tired as well.  I am down to my last floppy drive,
>
> You can replace a DD drive by an ordinary PC HD drive. The only
> gotcha is that PC drives are hard wired for drive B (which is
> why PC floppy cables have a twist), but that's a Simple Matter
> Of Soldering.

Correct. Most drives these days have a "zero ohm" SMD "resistor" set to
drive 1 (which is "A" on a PC). This has to be desoldered and placed on
the "drive 0" solder-field.
You also have to short the "disk-detect" switch. If you don't you'll
end up with overwriting files when changing disks!!
You also have to rotate the IDC connector 180 degrees and possibly
rewire the power connector.

And if you don't want to cut the ST's casing for the PC styled front
panel of the drive you have to modify it slightly for the old
frontpanel.
I've had success with several Sony drives and have written and drawn
documentation about this.
Just go to my "Atari launchpad" (see my signature), and when you get
there to the "hardware" section where you'll easily find it.


> I've been warned that disks *formatted* with a HD drive might
> not read well on a DD drive because of the weaker write current.

Never heard of this, but another issue which shows up a lot is people
using HD floppy disks as DD disks by fooling the drive (i.e. placing a
bit of tape over the "HD-detect" hole. This is certainly not a good
thing.
You should use HD disks for HD mode and DD disks for DD mode.

You should have no problems if you follow my instructions which will
exchange a broken DD (720 Kbyte) disk drive with a standard PC styled
HD drive. To be able to use it in HD mode (1.44 Mbyte disks) you need
some added electronics and a new disk-controller chip. I'm working on
this and will present it when I'm done, but until then you'll be fine
if you want to replace a broken drive.


Hallvard
-- 
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