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IBM 5170  -  Support for 3.5" Diskettes


IBM did not offer a 3.5" drive as an option for the 5170, although it is possible that some IBM resellers added a 3.5" drive for some customers.

The following assumes the use of the IBM supplied controller, the IBM Fixed Disk and Diskette Drive Adapter, not a non-IBM one with built-in BIOS.


720K

DOS version 3.2 introduced DOS support for 720K drives/diskettes.
Motherboard BIOS support is another consideration.
Although BIOS support for 720K drives/diskettes on 5170 motherboards does not appear until the second BIOS revision (06/10/85), the table below shows that 720K operation is excellent, even with the SETUP (CMOS SETUP) in a 'blank' state.


1.44M

DOS version 3.3 introduced DOS support for 1.44M drives/diskettes.
Motherboard BIOS support is another consideration.


IBM 5170 - First and second motherboard BIOS revisions

The first BIOS revision (01/10/84) and the second BIOS revision (06/10/85) do not support 1.44M drives. Therefore, with those two BIOS', booting from a 1.44M diskette (up to DOS 6.x) is not possible.

Limited operation (everything except for booting) may be possible using DRIVER.SYS, but attempts by me (and others) to use DRIVER.SYS for this task have failed.

Limited operation (everything except for booting) is possible by using a Backpack model 014350 (or similar). That is what I use on my early model 5170. Load the driver, and the 014350 will appear as a logical drive (e.g. G: ).


IBM 5170 - Third motherboard BIOS revision

The third BIOS revision (11/15/85) has full support for 1.44M drives.

After connecting a 1.44M drive to the internal controller, you will need to reflect that floppy drive type (1.44M) in the 5170's SETUP (CMOS SETUP). One known way to do that is to use GSETUP.EXE



Table

  • FORMATTING of diskettes excluded.
  • Boot diskettes of IBM DOS version 3.3
  • The 1.44M drive was one that supported both 2D (for 720K) and HD (for 1.44M) operation.
  • The 720K test diskette was an actual 720K, not a 1.44M with its density hole covered.
  • 'Read' means a successful read over the entire surface - more than simply getting a directory listing.

BIOS SETUP
state		 720K
diskette
read		 720K
diskette
write		 720K
diskette
boot		 1.44M
diskette
read		 1.44M
diskette
write		 1.44M
diskette
boot		    Comment
01/10/84 Blank YES NO YES NO NO NO  SETUP in 'blank' state (battery removed for 5 minutes)
01/10/84 A: set for 1.2M YES YES YES Note 1 NO NO  BIOS support: 360K / 1.2M
06/10/85 Blank YES YES YES NO NO NO  SETUP in 'blank' state (battery removed for 5 minutes)
06/10/85 A: set for 720K YES YES YES NO NO NO  BIOS support: 360K / 1.2M / 720K
06/10/85 A: set for 1.2M YES YES YES NO NO NO  BIOS support: 360K / 1.2M / 720K
11/15/85 Blank  YES  YES  YES  YES  YES  YES  SETUP in 'blank' state (battery removed for 5 minutes)
11/15/85 A: set for 1.44  YES  YES  YES  YES  YES  YES  BIOS support: 360K / 1.2M / 720K / 1.44M


Note 1  A DIR command results in a directory listing, but attempts to read files fail.