CONFIG.SYS & DRIVPARAM
Last revision of this page: February 24, 2025
DRIVPARM defines parameters for devices, such as device drivers and tape drivers, when you start MS-DOS. You can only use this command in your CONFIG.SYS file. The DRIVPARM command changes the parameters of an existing physical drive. It does not create a new logical drive. The settings specified in the DRIVPARM command overwrite the driver definitions for a previously defined device. [01]
DRIVPARAM is required whenever the floppy disk drive is not conform to the standard in which the system is installed. The command sets parameters when DOS is started to change the original DOS device drivers set.
I do not want to go into all the parameters here, just the form factor index [/ F: factor]. This indicates the type of drive. The default value is 2.
The following table can be found in all DOS manuals from about Version 4.01. But here are two values missing, namely the 3 and the 4!
| # | note |
|---|---|
| 0 | 160/180 KByte or 320/360 KByte |
| 1 | 1,2 MByte |
| 2 | 720 KByte (3,5" disk) |
| 5 | Harddisk |
| 6 | Magnetic tape drive |
| 7 | 1,44 MByte (3,5" disk) |
| 8 | Optical disk |
| 9 | 2,88 MByte (3,5" disk) |
However, if you look into a manual for versions 3.0 to 3.3, e.g. the Markt und Technik - Schnell PC Uebersicht (1988, page 252, ISBN 3-89090-567-6), then even the numbers 3 and 4 appear.
| # | note |
|---|---|
| 3 | 8 inch, single density (FM) |
| 4 | 8 inch, double density, (MFM) |
So something was possible after all. Try it out for fun, it doesn't work. The description single-density alone does not fit at all for 99% of the normal floppy disk controllers which were used in IBM-compatible computers.
But here we have a hint that it was basically possible to integrate 8 inch disk drives in DOS. But beware! There is MS-DOS, PC-DOS for the so called IBM compatible computers and the very special OEM DOS versions, e.g. for the NEC APC or SCP Cromemco S-100, etc.
I have found the decisive note in the Microsoft Knowledge Base Articles that only those formatting parameters are possible, which are also supported by the BIOS! This is very important! Have a look at: Q35766: Supported Values for FORMAT /N and /T Switches. In addition, only the number of sectors and tracks can be changed with the S and T parameters. However, not the bytes per sector. And this is the decisive factor.
In other words, MS-DOS basically supports 8 inch drives, but only for certain OEM versions. IBM PC-DOS has never supported 8 inch floppy drives, only 5.25 inch.
MS-DOS 1.25 [SCP OEM] [SCP Cromemco S-100] (8-inch DSDD)
This is a Seattle Computer Products OEM version of MS-DOS 1.25 for the 8086 SCP Gazelle with Cromemco 16FDC Disk Controller. This archive contains the original setup disk, and a work disk in ImageDisk format. The images are for 1.2mb 8-inch floppy disk media (77 tracks, 2 heads, 8 sectors per track, 1024 bytes per sector MFM) It also includes Basic-86 Rev 5.27 8-nov-82 and Perfect Writer (must be configured first). Important: These disks are NOT for IBM PC compatible hardware or IBM PC emulators. [02]
Summary
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