I see from time to time articles in various magazines,suggestions
on how to get 720K disk to format to 1.44Min 3.5 inch 1.44 meg drives.
They range from modifying the drives by adding shorting wires or blobs
of solder to defeat the Media switch to butchering the Disks themselves
by adding an additional hole to simulate a 1.44M disk. They also result
in the inability to format disk to 720k.

So here is my solution which eliminates the possibility of
irreversibly modifying either the disk or drive.

This applies specifically to the Toshiba 3.5 inch drive series ND356,
but may be applicable to drives of other makes. Some experimentation may
be necessary on other brands. It involves changing the jumper position on
the drive, and is derived through specification sheet and experimentation on
the drive that I own. The layout and description is of my own making.

FRONT OF DRIVE

Pin layout 1 5
2 6
3 7
4 8

BACK OF DRIVE

Pins shorted Meaning
1 to 5 Drive select 1

5 to 6 Drive select 2

2 to 3 Default "Media Select" - the one to defeat

3 to 4 Host select "Reverse Logic"
"Media Select" Disabled will format both
1.44M and 720K disks to 1.44 megs and will
format either to 720K if the /F:720 switch
is used on the command line for Format.

3 to 7 Host select "Standard Logic"
May work on your system if the above
doesn't.

7 to 8 Disables "Media Select" and will only
format both 720K and 1.44M to 1.44M
regardless of "Format" parameters used.

This file comes to you on a 720K disk formatted to 1.44 Megs in such a drive.