aureal wrote on 2022-05-14, 08:02:

Alistar1776 wrote on 2022-05-14, 06:42:

Question... if a 3.5 1.44mb FDD can read and write 720k 3.5 disks, can those disks still function just fine in a normal 720k FDD?

Yes they should read fine unless the 720k disk was formatted into a 1.44mb disk. On the ibm ps/2 it was not necessary to have the extra hole to format to 1.44mb either.

and a 1.44mb FDD cannot format 720k disks as 720k, only 1.44m?

It can format it to 720k or 1.44mb if you mod it with a extra hole. (unless you have a ps/2 drive and you dont need to mod it)

Alistar1776 wrote on 2022-05-14, 08:14:

aureal wrote on 2022-05-14, 08:02:

Alistar1776 wrote on 2022-05-14, 06:42:

Question... if a 3.5 1.44mb FDD can read and write 720k 3.5 disks, can those disks still function just fine in a normal 720k FDD?

Yes they should read fine unless the 720k disk was formatted into a 1.44mb disk. On the ibm ps/2 it was not necessary to have the extra hole to format to 1.44mb either.

and a 1.44mb FDD cannot format 720k disks as 720k, only 1.44m?

???
it's no problem to format a 720k disk in a 1.44MB drive. just specify it, ie FORMAT /F:720

weedeewee wrote on 2022-05-14, 10:38:

???
it's no problem to format a 720k disk in a 1.44MB drive. just specify it, ie FORMAT /F:720

oh ok. I didnt know that, thanks

aureal wrote on 2022-05-14, 08:02:

Yes they should read fine unless the 720k disk was formatted into a 1.44mb disk. On the ibm ps/2 it was not necessary to have t […]
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Alistar1776 wrote on 2022-05-14, 06:42:

Question... if a 3.5 1.44mb FDD can read and write 720k 3.5 disks, can those disks still function just fine in a normal 720k FDD?

Yes they should read fine unless the 720k disk was formatted into a 1.44mb disk. On the ibm ps/2 it was not necessary to have the extra hole to format to 1.44mb either.

Tetrium wrote on 2022-04-28, 09:50:

Virtually all the other 3.5in FDDs I found were HD drives except for a few which were 2.88 ED drives.

How could you tell when you had a 2.88 ED drive without a 2.88mb disk. Is it always on the label?

I have a weird 1.44mb fdd which on the back has less ground pins than normal. I thought they were ripped out and the drive was damaged but when I popped the model into google it seems to be like that. It is a Mitsumi D359m3d https://www.amazon.com/D359M3D-Mitsumi-Floppy … e/dp/B000EISIQ6 . Any ideas know why this is so? Its the only fdd I've seen like this.

One way (and imo the best way) is to look up the part number. This doesn't have to be 100% absolutely reliable though as there can still be some mis-information online about these drives. This was before the internet so when internet was finally a thing the 2.88MB drives were already archaic so little exists online from when these drives were actually current.

Most 2.88MB drives actually have "2.88" somewhere on the front bezel (usually either the eject button or it's just somewhere on the bezel). In some cases the stickers have a different color.

I found mine mostly from memorizing part numbers and going through stacks of 3.5in drives. I'd pick out any with "2.88" on the bezel right away so nobody else could snatch it up 😜

Some drives have fewer ground pins, I presume because it was cheaper to make them that way. Iirc Mitsumi D359 is a more recent drive so probably more cheaply made. The really old ones usually are build somewhat more robustly, kinda similar to how old ODDs are often a bit longer and often a lot heavier.