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IBM 5170  -  Floppy Drive Support


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Cable and Termination

• A diagram is at here.

• You need to use the particular cable shown at here.  The IBM controller expects it.  The cable manipulates both the motor-on and drive-select lines.

• Do not accidentally use the hard drive type of twisted cable.  Difference shown at here.

• For 5.25" drives, terminate as appropriate, per the diagram at here.


5.25" 360K floppy drives

DOS:  DOS 2.0 or later  (2.0 introduced DOS support for 360K floppies).
BIOS:  The IBM BIOS (all three revisions) on the IBM 5170 motherboard has full support for 360K drives/floppies.
Hardware:  The floppy controller that IBM supplied in the IBM 5170 supports 360K drives.


5.25" 1.2M floppy drives

DOS:  DOS 3.0 or later  (3.0 introduced DOS support for 1.2M floppies).
BIOS:  The IBM BIOS (all three revisions) on the IBM 5170 motherboard has full support for 1.2M drives/floppies.
Hardware:  The floppy controller that IBM supplied in the IBM 5170 supports 1.2M drives.


3.5" 720K diskette drives

DOS:  DOS 3.2 or later  (3.2 introduced DOS support for 720K diskettes).
BIOS:  Motherboard BIOS revision of 01/10/84:  Partial support.  See note 1 below.
Motherboard BIOS revision of 06/10/85:  Full support
Motherboard BIOS revision of 11/15/85:  Full support
Hardware:  The floppy controller that IBM supplied in the IBM 5170 supports 720K drives.


Note 1 01/10/84 BIOS
You can read from and write to 720K diskettes, but not format.
The ability to format can be gained by the use of DRIVER.SYS - see here.


3.5" 1.44M diskette drives

DOS:  DOS 3.3 or later  (3.3 introduced DOS support for 1.44M diskettes).
BIOS:  Motherboard BIOS revision of 01/10/84:  Partial support.  See note 1 below.
Motherboard BIOS revision of 06/10/85:  Partial support.  See note 2 below.
Motherboard BIOS revision of 11/15/85:  Full support.        See note 3 below.
Hardware:  The floppy controller that IBM supplied in the IBM 5170 supports 1.44M drives.


Note 1 01/10/84 BIOS
• You can read from and write to 720K diskettes.
• More information in the [3.5" 1.44M diskette drive - Detail] section following.
   
Note 2 06/10/85 BIOS
• You can read from and write to 720K diskettes.
• More information in the [3.5" 1.44M diskette drive - Detail] section following.
   
Note 3 11/15/85 BIOS
• Evidence is here.
• 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
• More information in the [3.5" 1.44M diskette drive - Detail] section following.



3.5" 1.44M diskette drive - Detail

  • 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.