f.y.i. Low density (DD) 3.5" floppies do not have a hole "top left" [looking at the label side with the shutter towards you]. High density (HD) FDs do have such a hole.

The finer details of DD and HD floppy discs is a bit of a minefield but this seems as good a place to comment as any...

So at the risk of techie-ing people to death...

When FD floppies first came out there was a brisk business in "DD to FD" converters, which just punched the extra hole. This was popular because HD discs were maybe 3 or 4 times more expensive than DD discs. The supporting premise was that "DD discs are just HD discs that have failed the stringent manufacturers testing. For home use there's usually no real impact." THIS IS WRONG. The magnetic media particle size and characteristics are different. Any disc used at cross purposes (be it DD used as HD or HD used as DD) will be (at best) less reliable than a disc formatted to its designed capacity.

On PCs this isn't usually an issue; most PCs check the hole and adjust the floppy disc operating characteristics to suit. Older IBM PCs (PS2 series) did not do this check; in my work there were regular problems caused when a disc wrongly handled in an IBM machine was used in a compaq portable (which does check).

I dont know if all keyboards look for the hole; so placing a DD disc in your floppy may not be detected as such. If the keyboard then treats the DD disc as an HD disc you will get problems; the disc may format but it WILL be untrustworthy.

Similarly if your gear uses DD discs then it is likely that using HD discs formatted DD will also be less reliable than use of DD discs.

[This message has been edited by MacAllcock (edited 05-23-2002).]