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Supersoft/Landmark Diagnostic ROM for 64KB-256KB version of IBM 5160 motherboard


Four RAM banks of 64 KB each.

Bank 0: 64 KB sized,  addressed 00000 to 0FFFF hex  (    0 KB to   64 KB)   (socketed)
Bank 1: 64 KB sized,  addressed 10000 to 1FFFF hex  (  64 KB to 128 KB)   (socketed)
Bank 2: 64 KB sized,  addressed 20000 to 2FFFF hex  (128 KB to 192 KB)   (socketed)
Bank 3: 64 KB sized,  addressed 30000 to 3FFFF hex  (192 KB to 256 KB)   (socketed)


On an IBM 5160 motherboard, socket U18 is where the Supersoft/Landmark ROM needs to be placed.

The Supersoft/Landmark ROM (in U18) does not require the IBM ROM in socket U19 to be present.  However, if not present, expect the U28 SYSTEM BIOS test to fail.

The 5160 motherboards require an EPROM of type 27256 or 27C256 (or equivalent), rated at 250 ns, or faster.
Burn the following image to such an EPROM, then place the EPROM in socket U18.
Note that at least one make-model of 27C256 is not suitable for this purpose - see here.

U18 image

Click here to see some people/companies that can use the image to supply and program/burn an EPROM for you.



Important Notes:

• Some video cards will not work with this PC (and XT) version of the Supersoft/Landmark ROM.

- My IBM MDA card works.
- My IBM CGA card works.
- My IBM EGA card will display, but poorly.

- My unbranded clone MDA card works.
- My unbranded clone CGA card works.

- None of my VGA cards work.  More information here.
• When the Supersoft/Landmark ROM is fitted to an IBM 5160 motherboard of type 64KB-256KB, it will test 640 KB of RAM  (irrespective of what SW1 is set to).
if you do not have 640 KB in the computer (motherboard + expansion card) then the SYSTEM MEMORY TO A0000  test will fail.
• The KEYBOARD CONTROLLER  test will fail if no XT-class keyboard is connected to the 5160 motherboard.
• The FLOPPY CONTROLLER  test requires that a floppy controller card is fitted to the 5160 motherboard.  For this test, the card does not need any drives connected to it.
• The FLOPPY READ  test takes about 1.5 minutes to fail.  Be patient.
• The NONMASKABLE INTERRUPT  test will fail if the math coprocessor (8087) is absent and you have switch 2 on SW1 in the wrong position for that (off).
• The SLOW REFRESH TO A0000  test takes a few minutes to go through 640 KB of RAM.


Minor Notes:

• This is the same diagnostic ROM used for the IBM 5150.  It suits the 5150, 5155 and 5160.
• Make sure that SW1 is set according to how banks of motherboard RAM that you have populated, noting that per above, the diagnostics are expecting 640 KB of RAM to be fitted in the computer.
• References to chips are for the corresponding chip on a 5150 motherboard.  For example, the second test displays U33 SUPERSOFT ROM CHECKSUM  even though the Supersoft/Landmark ROM is in socket U18  (not the quoted U33)
• Ignore the boxes labelled, "PC SW1" and "PC SW2".  They are for when the ROM is used in an IBM 5150 (IBM PC).
• The term 'KEYBOARD CONTROLLER' is misleading.  Unlike the IBM 5170, the IBM 5160 does not have a keyboard controller chip.  Discrete components are used instead.
• There is nothing in the manual that indicates that codes are sent to port 80h.
• An example output is shown at here.
• The Supersoft/Landmark ROM even generates a display if there is no RAM fitted to the 5160 motherboard.  What will happen is that only the first 8 tests will run, not going any further than the 16K CRITICAL MEMORY REGION test.  The intention here is that you do whatever is required to get the first 16K of RAM operational and then the diagnostics will run all of the tests.