In IBM 5160, the BIOS dated 01/10/86 adds support for 720KB floppy drives.
I installed a 1.44MB FDD (for use with DD media, of course) in some late XT clone, one with that highly-integrated Faraday chipset.
It would be reasonable to assume that such a late clone has a BIOS with all the features of IBM's 01/10/86.
But there's a problem: by default DOS treats that FDD as a 360KB one, attempts to format a 720KB diskette (format /f:720) result with "Parameters not compatible..." error.
DRIVPARM solves the problem.
Does it mean that my BIOS lacks support for 720KB drives?
IBM 5160 with a late BIOS doesn't need DRIVPARM here, does it?
Using PC DOS 2000, if that matters.
IIRC, I needed the DRIVPARM command to get what you're doing to work in a late version IBM 5160. In fact, I was unable to use PCDOS 3.x or FREEDOS 7.x because they don't include the DRIVPARM command. One FREEDOS site mentioned deliberately leaving the command out because no one would actually ever use it. MSDOS 4.x, 5.x, and 6.x all work fine at this point.
It's been a while since I touched it, but I seem to recall having some trouble formatting 720k floppies and needing to sneaker-net them to an older machine running Windows 98. Be advised that some newer machines that have 1.44m floppies will not recognize a 720k floppy no matter what flags you specify. Some newer versions of Windows seem to alter the boot block of any floppy inserted into the drive. Then you get the mysterious "invalid media" or some such when you take your known good disk back to your antique system.
What you're trying to do is very workable. But there are a few bumps in the road. I think there's a how to on Modem7's minuszerodegrees.net site that I looked at as well. I'll look at my system a bit later today and verify what I did to get it to work and update this post accordingly.
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I wanted to check what I have currently running on my 5160 for a quick answer but instead found only another riddle. I'm pretty sure I used something like:
drivparm=/d:0 /c /h:2 /s:9 /t:80
in config.sys to get the system to treat a 1.44m drive as a 720k. But upon checking the MSDOS 6.22 boot floppy currently in the 1.44m drive hooked up as drive A:, and the root directory of the CF card acting as drive C: I find no config.sys on either one. Yet the system will boot up off of either and the A: drive will read a 720k floppy. But I do recall moving up from PCDOS 3.x that came with the machine specifically because that system didn't have the DRIVPARM command. I tried but didn't stay with the DRIVER= command because IIRC it assigned the 720k drive a different drive letter. All I had at that time was MSDOS 5.x on 360k floppies, MSDOS 4.x on 720k floppies, and an MSDOS 6.22 upgrade set on 1.44m floppies. I had managed to get bootable 720k floppies built of all three versions, and the system booting off of a CF card resident version of each before life pushed the project, not to the back burner, but completely off of the stove. Logic tells me what I have should not be working but it is. The only variable I can't quickly account for is, could the system now be happy with an A: drive that's a Sony 1.44m masquerading as as 720k due to the addition of an XT-IDE card? The XT-IDE in the system is a Glitch Works rev3 card (which works like a champ by the way). Upon restart, the system comes up into the BIOS resident on the XT-IDE card and allows you to select the boot device. So I'm not using a plain vanilla IBM 5160 boot process at the current time.
