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Supersoft/Landmark Diagnostic ROM for 64KB-256KB version of IBM 5150 motherboard


Four RAM banks of 64 KB each.

Bank 0: 64 KB sized,  addressed 00000 to 0FFFF hex  (    0 KB to   64 KB)   (soldered to motherboard)
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 5150 motherboard, socket U33 is where the Supersoft/Landmark ROM needs to be placed.

To use a 27xxx series EPROM (e.g. 2764/27128/27256/27512) in socket U33, you will require a suitable adapter (adapter details).

U33 image for a 2764 EPROM (or 27C64) in a MK36000/2764 adapter ( or in 2364/27128 adapter, such as the one at here )
U33 image for a 27128 EPROM (or 27C128) in a MK36000/27128 adapter ( or in 2364/27128 adapter, such as the one at here )
U33 image for a 27256 EPROM (or 27C256) in a MK36000/27256 adapter ( or in 2364/27256 adapter, such as the one at here )
U33 image for a 27512 EPROM (or 27C512) in a MK36000/27512 adapter ( or in 2364/27512 adapter, such as the one at here )



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.

If a RAM error at address 05040 is reported, note that the "05040" bit is incorrect.  Do not believe the "05040" - the diagnostics have displayed the wrong address.
The SYSTEM MEMORY TO A0000  test will fail if 640 KB (A0000 hex = 640K) of RAM is not fitted.
So, that is 256 KB on the motherboard plus 384 KB on an expansion card.
RAM related switches on the motherboard are ignored (switches SW1:3 and SW1:4, and SW2).
If the only RAM fitted is the 256 KB on the motherboard, expect to see errors when the test advances past address 40000 (256K = 40000 hex).
The KEYBOARD CONTROLLER  test will fail if no PC-class keyboard is connected to the 5150 motherboard.
The FLOPPY CONTROLLER  test requires that a floppy controller card is fitted to the 5150 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 U28 ROM  test is expected to fail, because there is nothing in the U28 socket.


Minor Notes:

It is observed that when a test fails, the Supersoft/Landmark ROM switches the motherboard relay on/off three times.  (The clicks are very audible.)
The settings of the switches within SW1 on the 5150 motherboard are ignored, except for switch 2.
The settings of the switches within SW2 on the 5150 motherboard are ignored.
Switches 3 and 4 within SW1 on the IBM 5150 motherboard do not enable/disable RAM banks.  The 4 motherboard banks are always enabled.  That is why in the IBM 5150, all motherboard RAM banks must be populated before RAM is added via expansion card/s.
Ignore the box labelled, "XT SW1".  That is for when the ROM is used in an IBM 5160 (IBM XT).
The term 'KEYBOARD CONTROLLER' is misleading.  Unlike the IBM 5170, the IBM 5150 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.