Top 50 DOS Problems Solved: Doubling Disk Capacity

Q: I have been told that it is possible to convert 720K 3.5-inch floppy disks into 1.44Mb versions by drilling a hole in the casing. Is this true? How is it done? Is it safe?

A: It is true for the majority of disks. A few fail immediately, but the only way to tell is to try it. The size and placement of the hole is, near enough, a duplicate of the write-protect hole.

If the write-protect hole is in the bottom left of the disk, the extra hole goes in a similar position in the bottom right. Whatever you do, make sure that all traces of plastic swarf are cleared away. As to whether this technique is safe, it is a point of disagreement. In theory, you could find converted disks less reliable. My own experience over several years has been 100 per cent problem free other than those disks which have refused to format to 1.44Mb in the first place.

You can perform a similar trick with 360K and 1.2Mb 5.25-inch disks.

Hands up who remembers doing this. I certainly do…

6 thoughts on “Top 50 DOS Problems Solved: Doubling Disk Capacity

    • Oh, I’m sure lots were, because this was a cheapskate thing to do. I was a schoolboy, so I did it. My parents, running a business, did not :-)

  1. I upgraded from dual 360K drives to a high density 3.5″ disk so late that 1.44MB disks were reasonably priced.

    The trick that was worthwhile, even at this late state, was jamming a few extra tracks on your HD 3.5″ disk to increase its capacity still further. This was so popular that some software install disks had this done to them by the vendor! Wikipedia tells me this was Microsoft, and they fit 1.68MB on said disks.