IBM 5160  -  Possible Problem in 05/09/86 BIOS Revision

There is a possibility that something in the 05/09/86 BIOS is interferring with the ability of some third-party floppy controllers to boot from 1.44M diskettes.

1. This is suggested at the Vintage Computer Forums in thread #49245

2. It would explain the symptom that I experience with the third-party floppy controller shown below.  I see the symptom with the 01/10/86 BIOS as well.

unique_fdc.jpg PROBLEM:

Using this card on a IBM 5160 motherboard, unless the motherboard's BIOS revision is the first one (11/08/82), I cannot boot from known good 1.44M sized MSDOS boot diskettes. Reading is fine; just cannot boot.