Epson Apex 20020 - Manual (Page 214)

See Appendix D for instructions on performing a low-level
format. If you need to format the disk, be sure to do it before
completing the steps in this appendix.
WARNING
The procedures described in this appendix destroy any data
on the hard disk. If your disk contains data, use the
BACKUP command to copy all the data before completing
the steps described here. See your MS-DOS Reference
Manual for instructions on using BACKUP.
Partitioning the Hard Disk
You need to partition the hard disk so it can run the MS-DOS
operating system. The partitioning process divides the single
physical disk into one or more logical drives. You can access each
logical drive as though it were a separate physical device. The
first logical drive is drive C, the second is drive D, and so on.
Note
If you install a second hard disk, MS-DOS refers to that disk
automatically as drive D. In this case, the second logical
drive on your first disk is referred to as drive E, the third is
drive F, and so on.
The first logical drive (drive C) is also called the primary
partition. All remaining logical drives together make up what
MS-DOS calls the extended partition. Extended partitions are
necessary on a hard disk with a capacity greater than 32MB
because MS-DOS (version 3.3) cannot manage more than
32MB at a time.