IBM 5160  -  BIOS Revisions

On the 5160 motherboard, there are two BIOS ROM chips, one in socket U18 and the other in socket U19.

There were 4 revisions of the BIOS, differentiated by date (there are no version numbers).
The table below lists the dates, and the unique 7-digit IBM part numbers that are located on the top of the ROM chips.

Because of the apparent scarcity of the 5000026 chip, and other reasons, it is possible that the 08/16/82 revision was not publically released.  See here.

The date format used is MM/DD/YY.

  Part numbers, where BIOS supplied
in masked ROM form
Part numbers, where BIOS supplied
in EPROM form
ROM / EPROM type supplied Floppy/diskette
drive support
08/16/82 U18=5000026, U19=5000027   (photo)    U18=MK38000, U19=MK37000 360K See here
11/08/82 U18=1501512, U19=5000027   (photo)
U18=1501512, U19=6359116   (photo)
   Varies - see photos 360K See notes 1 and 2 and 6 below
01/10/86   U18=62X0851, U19=62X0854   (photo)
U18=62X0852, U19=62X0853   (photo)
 Both 27256 360K, 720K See notes 3 and 4 and 5 below 
05/09/86 U18=62X0890, U19=68X4370   (photo) U18=59X7268, U19=62X0819   (photo)  Both 27256 360K, 720K See notes 3 and 4 and 5 below 

Click here to see the memory layout of the BIOS chips within the IBM 5160.

BIOS replacement/upgrade

If your IBM 5160 motherboard does not have the 05/09/86 revision of BIOS, upgrading to the 05/09/86 revision is valid (although read notes 3 and 4 and 5 below).

Unlike with modern computers, you can not simply 'flash' a new BIOS onto the 5160 motherboard - you need to physically replace the two BIOS ROM chips.  New BIOS ROM chips are normally created by 'burning' an image of the BIOS into suitable EPROM chips (via an EPROM programmer):

27256 EPROM's can be replaced with 27C256  (or equivalent).

On the early IBM 5160 motherboards, the TMM23256/MK37000/MK38000 ROM's can in most cases be replaced with 27C256 EPROM's, but some brands of 27C256 may be unsuitable - see here

For the IBM 5160, use EPROM's that are rated at 250 ns, or faster.  (Reference.)

ROM content images for programming/burning into an EPROM are at here.

Click here to see some people/companies that can supply and program/burn EPROM's for you.

Hard drive support

In an IBM 5160, the motherboard BIOS does not influence the types/capacities of hard disk drives that can be used.  That is determined by the particular XT-class hard disk controller card that is fitted (and the operating system).

Note 1 In the 11/08/82 BIOS revision, 720K diskette operation is partially supported.  More information is here.
Note 2 Refer to the diagram here.
In the two 1982 dated BIOS revisions, chip U19 contains part of cassette BASIC and thus is not critical to operation of the computer (only cassette BASIC is lost).
For that reason, if the POST in those BIOS' discovers that U19 has failed, the POST will display "F6000 ROM" and allow booting to continue.

This is not the case for the 1986 dated BIOS revisions, because in those, U19 also contains part of the BIOS.  If U19 fails in those, the motherboard will appear 'dead'.
Note 3 The two 1986 dated BIOS revisions (01/10/86 and 05/09/86) may cause the symptom described at here.
Note 4 The two 1986 dated BIOS revisions (01/10/86 and 05/09/86) may not support an IBM 5161 - see here.
Note 5 The two 1986 dated BIOS revisions (01/10/86 and 05/09/86) contain code for 1.2M drives, however, to use a 1.2M drive, it is not as simple as upgrading the floppy controller to a high density (HD) one.
See here.
Note 6 The copyright string in some 1501512 ROM's is "1501512 COPR. IBM 1981", and "1501512 COPR. IBM 1982" in others.  The ROM's are functionally the same.