That 250 MB drive has been DoubleSpaced by either DOS or Windows.
Let me explain a few things...
A drive storage is build up in clusters.
One cluster can litterally house ONLY ONE file, even if more files wil fisically fit in that cluster. (32Kb on FAT-16 means 31Kb lost when placed an 1Kb file in it)
As you see, with small files, there is wasted space!
There comes DoubleSpace, and lateron DriveSpace.
This is what happens when you use one of those:
1 A small piece of drive wil be leaved intact, the rest will be used to house ONE gigantic file. (dblspace.000)
2 The label is renamed so the operator can determine the way the drive was used
3 INSIDE that large file, your complete contens of your hard drive is stored head-to-tail in it, so there is NO wasted space by allmost empty clusters.
4 In the OS, in conjunction with the statements in Config.dos and Autoexec.dos there wil be a conversion shell started who "Creates" a virtual disk and links the file "dblspace.000" to it.
5 The norml disk "C" will be moved to drive "D"
6 The virtual disk becomes the new "C".
Those drives should NOT be used in a multi-drive system.
If you want to access your data, start it up ALONE in the system.
You could be copying the files to a floppy, or begin a "DiskJockey" session.
In a Multidrive system, "C" wil be assighned to the Primairy master, Partition 1.
"D" will be assighned to Primairy slave partition 1.
"E" will be assighned to Primairy Master partition 2.
"F" will be assighned to Primairy Master partition 3.
... untill ALL partitions on the Primairy master are assighned.
The rest of the slave's partitions will follow up.