In an IBM 5150 or 5155 or 5160, a 1.44M diskette drive connected to the IBM 5.25" Diskette Drive Adapter will not work at 1.44M capacity (in part, due to lack of High Density support on the card), but will work with 720K diskettes.
Ability
Comment
Boot
Yes
IBM DOS 3.3 and IBM DOS 6.2 known to work
Read
Yes
Write
Yes
Format
[see below]
Click here for information about formatting a 720K diskette.
If you have an IBM 5150, and that 5150 has the 16KB-64KB version of the 5150 motherboard, click here for details of a known issue.
On Your IBM 5150/5155/5160
Connect a 'standard' 1.44M diskette drive to the 'IBM 5.25" Diskette Drive Adapter' in your 5150/5155/5160 as drive A: (physical drive 0)
Some connection options:
- To use the existing IBM supplied cable, one of these plugged into the 1.44M diskette drive. A source of those is at here.
- You can use the cable pictured at here in reverse to how it is normally used. Make sure that you use the floppy type of twisted cable, not the hard drive type. [photo here]
The 5150/5155/5160 can now boot/read/write a 720K diskette.
(Formatting a 720K diskette is a different story. Click here for more info.)
Creating a 720K Boot Diskette Using Your 'Modern' Computer
Requirement: Your 'modern' computer has a 1.44M diskette drive, internal or USB. Requirement: If using a USB type of 1.44M diskette drive, that the drive also supports 720K diskettes. See here.
Note that following, we will not be getting WinImage 9 software to do any formatting of the diskette. Instead, formatting will be done at a command prompt prior to using WinImage. The reason is that, in Windows 10, I find that WinImage 9 cannot do formatting of 720K diskettes, even when 'run as Administrator'.
1. Obtain a 720K diskette that you are prepared to overwrite. See here for the difference between 720K and 1.44M diskettes.
A 1.44M diskette with its density hole suitably covered should work instead - not a legitimate action, but it should work for the purpose of what we are about to do in the following steps.
4. Download WinImage 9 software from http://www.winimage.com and then install it.
5. Download file ibm_dos_33_on_720k.imz (an image file of a 720K sized IBM DOS 3.3 boot diskette) to your hard drive.
6. In Windows Explorer, double-click on the downloaded ibm_dos_33_on_720k.imz file.
As a result, WinImage should open, showing the contents of the image file.
7. On the WinImage menu bar, select DISK and in the menu shown, verify that the drive selected is your 1.44M one.
8. On the WinImage menu bar, select DISK and then WRITE DISK. WinImage should start writing to the pre-formatted diskette.
9. When WinImage has finished writing the diskette, close WinImage.
You now have a 720K sized IBM DOS 3.3 boot diskette for your IBM 5150/5155/5160.
