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1.44 mb floppy in dos when bios support is only for 720k Floppy

alexfloca

Experienced Member
Joined
Jan 27, 2012
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87
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Transilvania, Romania
Hi all,

Does anybody have a clue how a 1.44 Mb floppy drive can be accessed under dos if the bios supports only 720 k floppy drives, the data rate should not be a problem as for the 5,25" floppy drive it supports 1.2 Mb diskettes. I already tried the drivparm in config.sys but without any luck. Maybe I did something wrong.

regards,
alex
 
Does the drive work in 720k mode? Does it power? Let's eliminate other potential failure points.

What version of DOS are you using? Also, post computer and BIOS information; it is possible that you could have a BIOS that supports 1.2 MB drives but not any form of 3.5" drive. I don't know of any but I have seen multiple references to BIOS updates sometimes being needed. If you are on a system with DOS 5 or 6 and a BIOS dating after 1985, I expect the problem lies in how drivparm or driver.sys was setup.

Post your drivparm; it should be possible with drivparm to do this with any version of MS-DOS 3.1 or later. However, it seems that 3.30 does not support drivparm which was fixed in a 3.30a update. And the drivparm switches have changed in some versions.
 
hi, thank you for the reply. The drive is a 1.44M drive and works great in 720k mode with this computer. The PC is a Siemens PCD-2 with bios support for "double density", "high density" (5,25") and " 3,5" inch" floppy drive.

DOS version 5.0, bios is dated 1982.

I tried to setup drivparm as follows:

drivparm= /D:1 /F:7 /I -not working (the drive B can't read any 1.44 mb floppyes)
drivparm= /D:1 /H:2 /S:18 /T:80 -not working (the drive B can't read any 1.44 mb floppyes)
drivparm= /D:1 /H:2 /S:18 /T:80 /I -not working (the drive B can't read any 1.44 mb floppyes)

with the second drive disabled from the Bios
device=C:\DOS\driver.sys /D:1 /F:7 - not working, it "installs" correctly a drive E (i have 2 partitions C and D on the hard drive) but when trying to acces the drive E it just says I have to insert a disc and press enter, but it won't work.
If I try to acces the drive B: it reads from the 5,25" fdd (A drive)
 
Hang on. Your BIOS supports High Density floppy drives? Well set the B: as high density and try to read a 1.44mb disk and see what happens.

Double Density = 360k 5.25" and 720k 3.5" drives
High Density = 1.2mb 5.25" and 1.44mb 3.5" drives.
 
I have read that some AT compatibles did not work with DRIVPARM. If nothing else works, try using DRIVER.SYS in CONFIG.SYS.

But everything I see suggests that what you have done should work so either I am missing something obvious or the problem is specific to Siemens models and you may need to make a follow on post to find someone with Siemens experience.
 
hi lutiana,

thanks for the sugestion but it doesn't work, if I set it to high denisity it acts like a 5,25" 1.2 Mb FDD.
krebizfan, thank you, I think this might be my case, i tried configuring it with driver.sys but it doesn't work. I guess it will remain like this, at least I can use it as a 720 k FDD.

Thank you all
 
hi lutiana,

thanks for the sugestion but it doesn't work, if I set it to high denisity it acts like a 5,25" 1.2 Mb FDD.

How does it act like 1.2mb drive? When you format a disk in it? Does it read 1.44mb disks formatted on another machine?

What is the exact wording in the BIOS for the setting?
 
i tried everything to get the 1.44 MB FDD act as a 1.44 MB FDD on the Siemens PCD but no luck, I will leave it like this and use 720k formatted floppies with it.
 
i tried everything to get the 1.44 MB FDD act as a 1.44 MB FDD on the Siemens PCD but no luck, I will leave it like this and use 720k formatted floppies with it.
Just curious: Who makes the BIOS ROM(s) and is the setup routine built in or do you need a program on diskette?

I assume that drive A is a 1.2MB HD drive, you're positive that the 3.5" HD drive is working perfectly, and the 3.5" HD diskettes are also perfect?
 
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