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Supersoft/Landmark Diagnostic ROM for 256KB-640KB version of IBM 5160 motherboard


Two banks of 256 KB and two banks of 64 KB.

Bank 0:	256 KB,	starting at address 0
Bank 1:	256 KB,	starting at address 40000 hex  (256K)
Bank 2:	64 KB,	starting at address 80000 hex  (512K)
Bank 3:	64 KB,	starting at address 90800 hex  (578K)

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

As for the ROM in socket U19, although not mandatory, leave it in place.

The 5160 motherboards require an EPROM of type 27256 or 27C256 (or equivalent), rated at 250 ns, or less.
Burn the following image to such an EPROM, then place the EPROM in socket U18.

U18 image



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.
•	The SYSTEM MEMORY TO A0000  test will fail if less than 640 KB of RAM is fitted (motherboard and/or expansion card). This is irrespective of what the SW1 switches are set to.
•	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 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.
•	An example output is shown at here.
•	On this 256KB-640KB motherboard, the 16K CRITICAL MEMORY REGION test needs only motherboard bank 0 to be populated.
•	On this 256KB-640KB motherboard, the MEMORY REFRESH test needs only motherboard bank 0 to be populated.
•	Make sure that SW1 is set according to how banks of motherboard RAM that you have populated, noting that per above, a total of 640 KB of RAM is required for the SYSTEM MEMORY TO A0000 test.
•	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.
•	The Supersoft/Landmark ROM even generates a display if there is no RAM on the motherboard.  More information here.