Formatting 720KB Floppy under XP/Vista

**Harrison** · 9th October 2008, 19:50

As some of you know, from the introduction of XP onwards it no longer supports the formatting of floppy disks smaller than 1.4MB. So how do we format a DD floppy disk as a 720KB PC disk to use for transferring files to an Amiga?

There are two fairly simple solutions. The first is still built into Windows.

Method 1:

Open a new command prompt by going to Start->run and typing CMD
Insert your blank floppy disk into the drive.
Type Format A: /T:80 /N:9
Your floppy disk will be formatted as a 720KB Double Density Floppy Disk ready to be read by an Amiga.

Method 2:

Download the program FMT (attached to this post)
Extract the FMT.EXE file anywhere on your HD in a location you will remember.
Open a new command prompt by going to Start_>run and typing CMD
Navigate to the location of the FMT.EXE file on your HD
Type FMT A: /f:720
Your floppy disk will be formatted as a 720KB Double Density Floppy Disk ready to be read by an Amiga.

Both of these methods work just as well, so it is up to you which one you use.

If you look at the command for the Windows Format command, from XP you now need to specify the number of tracks and number of sectors to format a 720KB disk. Before XP you used to be able to type Format A: /f:720 just as you do for the FMT command. But that now no longer works so you need to specify the tracks and sectors.

The FMT program has some interesting options beyond just formatting a 720KB disk. If you also need to format other sizes it supports many different ones from 360KB up to 1.68KB.

To read a 720KB PC formatted floppy disk in an Amiga you must have a version of CrossDOS installed on your Amiga. This is built into Workbench from version 2.1. If you have an older version of Workbench then you will need to try and get hold of the standalone version of CrossDOS and install it into your copy of Workbench.

With WB2.1+ you first need to mount the PC0: device driver by typing mount PC0: into an Amiga shell. Then you can insert the PC formatted floppy and the Amiga will be able to read and write to it.

**Harrison** · 9th October 2008, 22:32

Something strange I just encountered that I remember being a problem back when I used Amigas as my main system was how fussy they are at reading PC formatted floppy disks.

I just formatted a 720KB disk on a PC, copied some files onto it, put it into the Amiga, the Amiga recognised it as a PC disk, I could access the contents, but when i tried to copy them onto the Amiga HD Workbench threw up CRC and cyclic redundancy error messages.

So I remembered that sometimes formatted the disk on the PC didn't always work, so I formatted it again as a PC disk from the Amiga. But then the PC couldn't read the disk!

So next I tried formatting the disk on the PC again and the same thing happened again. Same read errors on the Amiga.

Finally I formatted the disk as a standard 880KB Amiga disk, then formatted it again on the Amiga as a PC disk. This time the PC read the disk perfectly well, and when I copied some files onto the disk the Amiga read and copied the files perfectly to its HD.

So what causes this strange behaviour? Does the Amiga sometimes not really format the disk completely if it thinks the disk is already in the right format, so the PC has trouble understanding it? And why would formatted the disk on the PC cause read errors when the Amiga tries to read it? Strange. For a moment I thought the Amiga's drive as dying!

**woody.cool** · 10th October 2008, 12:48

Are you using DD or HD disks?
HD disks (with the hole taped over to make it be recognised as a DD disk), don't work as reliably when used as DD (720KB/880KB) disks - it's best that you use proper DD disks.

**Harrison** · 10th October 2008, 14:37

I'm using real DD disks. I first tried with a used disk from my Amiga disk boxes, but when that cause read errors on the Amiga I thought the disk might be old and damaged so I opened up a new pack of Sony DD floppy disks (I've a few packs of 10 Sony DD disks still sealed) and the same errors happened until I first formatted the disk as an Amiga disk and then as a PC disk. Since doing that it has worked perfectly.