It is like the war with viruses and bacteria. Whenever the medicos come up with an antibiotic, the virus and bacteria mutate and build up an immunity. Stronger anti-biotics then have to be developed and so it goes on. Who will give up first the microbes or the chemists?
It is the same with hardware and software developers. As soon as the hardware gets faster and the hard disks larger, along comes a software writer to take up the extra capacity, pushing it to the edge. So hardware developers bring out even faster and larger capacities to handle the software.
No hard disk ever seems big enough.
Stac then introduced an compression program that compressed and decompressed in the background. This idea was used by Microsoft in DOS 6.0 with a sub-program called DoubleSpace, but after a court action Microsoft backed off and later versions of DOS do not carry it. DoubleSpace and Stac in effect doubled the hard-disk capacity. If you buy it for $100 or so either with DOS 6.0 or as stand-alone Stac it is a bargain. Upgrading a 40MB disk to 80MB can cost $400 to $500, though you would probably go to 120MB anyway.
However, the Microsoft DoubleSpace version is no longer available. Moreover, those who thought they were lucky enough to get with with DOS 6 may not be so lucky. It was not completely glitch-proof.
Both Stac and Double-Space work in the background compressing and decompressing files as you use them. You do not know they are running.
Now a program called Infinite Disk goes a step further. It compresses files that have not been used for several days (the user determines how many) and leaves them on the hard disk. If they are not used for, say a week or more, it prompts the user to export them to floppy disks, but it keeps the name of the file on the hard disk. If the user starts a program that requires that file or calls up data that requires that file, the user is prompted to insert Floppy Disk No 1 (or whatever number the file is on) and the file is decompressed on to the hard disk.
The hard disk space thus becomes almost limitless. The program is $199 and is in DOS or Windows (Phone 02 8887965).
On balance, it is priced too high considering the declining cost of upgrading hard drives, but laptop owners, who cannot upgrade without trading in the whole machine, should investigate it. It is easy to use. The windows work well. And there are a lot of compression statistics available. It will work in conjunction with already-compressed files, but will not compress them further.
A word of warning: always back-up before using any compression programs.