 The magazine of the Melbourne PC User Group Drive Me Crazy! Tom Coleman |
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I remember the fun and games I had the first time I had to replace a 5.25 inch 360 kB drive B: with a new 3.5 inch 720 kB drive. At first it seemed pretty straightforward: unplug the plugs, unscrew the screws, take out the old drive, assemble the 3.5 inch drive in the frame, insert the drive then plug in the plugs and screw in the screws. Bingo!
It did not take long to discover that I now had a 360 kB 3.5 inch disk that the computer treated as if it was a 5.25 inch. Having installed the drive I now had to find a way of telling the computer that the new drive was a different size.
There are two ways of doing this. The first is with the DRIVPARM command in CONFIG.SYS. Just add the line:
DRIVPARM=/D:dd /F:ff
where dd is the drive number,
| 0 for A: 1 for B: 2 for C: and so on ff is the form switch where 0 = 320/360 kB 1 = 1.2 MB 2 = 720 kB 3 = 8 inch single density 4 = 8 inch double density 5 = Hard disk 6 = Tape Drive 7 = Other (inc 1.4 MB) |
There are some other parameters covering changeline, tracks and sectors but the defaults are good enough in almost all cases.
If you don't specify /F:ff you get 720 kB which is /F:2
Easy. Too easy. It didn't work.
It seems that Microsoft in their wisdom disabled DRIVPARM for IBM versions of DOS and forgot to turn it back on again for their own release.
Some OEMs were awake and tweaked their version of Dos to re-enable DRIVPARM but most just passed it over.
At the risk of being banned from the inner circles of the Ancient and Mystical Order of the Dos Voodoo Priests I am going to reveal the secret of how to re-enable DRIVPARM if it does not work for you either.
You replace the equals sigh with three Control As thus:
DRIVPARM^A^A^A/D:dd /F:ff
Try it if you need to. It will bring up the new drive with the designated drive letter. Drive B: in my case.
Well thaYs not quite true, because if your BIOS does not support the drive type you specify with / D : dd then it will not work anyway. Fortunately it is only older BIOSs that will give this problem
I said that there were two ways. Here is the other.
You can put the following line into your CONFIG.SYS
DEVICE=C:\DOS\DRIVER.SYS /D:dd /F:ff
The parameters are the same as for DRIVPARM.
Note that the full filespec is given for DRIVER.SYS. You would need to modify it to reflect the location of your DRIVER.SYS. It is not enough that DOS is in your PATH because the PATH is not set until
AUTOEXEC.BAT is executed. The order of execution is CONFIG.SYS then COMMAND.COM and finally
AUTOEXEC.BAT.
DRIVER.SYS is installed from CONFIG.SYS only. You cannot do it at any other time.
At the time that I set up my disk drive with DRIVER.SYS (I had not yet been through the
DRIVPARM ritual initiation) my hard disk was partitioned into drives C: and D:.
The effect of DRIVER.SYS was to recognize the drive as 3.5 inch 720 kB drive E:, the next available letter. However drive B: was still the 360 kB 3.5 inch drive it was before. It was a bit confusing so I put the following line into my
AUTOEXEC.BAT.
ASSIGN B = A
Note no colons after the letters.
This has the effect of rerouting activity for drive B: to drive A:, which in my case really was a 5.25 inch 360 kB floppy.
This raises an interesting aside.
If you have a 5.25 inch 1.2 MB drive A: and a 3.5 inch 1.4 MB drive B:, you could put the following lines into your CONFIG.SYS.
DEVICE=C:\DOS\DRIVER.SYS /D:0 /F:1
DEVICE=C:\DOS\DRIVER.SYS /D:1 /F:2
This would recognize the first drive (/D:0) or drive A: as a 360 kB drive (/F:1) and assign it the next available drive letter, say E:. Similarly the second drive (/D:1) would be recognized as a 720 kB drive (/F:2) and assigned the letter F:.
Now drive A: is 1.2 MB 5.25 inch, drive B: is 1.4 MB 3.5 inch, drive E: is the same drive as drive A: but is 360 kB 5.25 inch while drive F: is the same drive as drive B: but is 720 kB 3.5 inch.
So with two physical drives you have four different logical drives that you can access simply by using the appropriate drive letter.
Such shenanigans may not be meaningful to your kind of computing but it can be a life saver for some.
It is the kind of know how that seems that it should have a use but you can't be sure what to do with it. The best use I have found, so far, is to write an article for
PC Update.
Reprinted from the November 1992 issue of PC Update, the magazine of Melbourne PC User Group, Australia
