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Supersoft/Landmark Diagnostic ROM
suitable for most clones of the IBM PC and IBM XT



  WARNING:
The Supersoft/Landmark Diagnostic ROM is not known to detect RAM addressing problems.
Ruud's Diagnostic ROM detects most.


This is not a clone specific version of the diagnostic.  It is exactly the same diagnostic targeted for the IBM PC family.  From the user manual, "IBM PC, XT, AT-286, AT-386, AT-486, or 100% compatible".

The "100% compatible" is Supersoft 'giving themselvs an out'.  Why?  Because there is no such thing as a 100% compatible clone.  In some clones, one or more tests will fail, even if the clone is fully functional.

This is the PC and XT variation of the diagnostic, intended for the IBM 5150 (IBM PC), IBM 5160 (IBM XT), and clones of those.

You remove the BIOS ROM from the motherboard, and in its place, fit the Supersoft/Landmark Diagnostic ROM.

An example screen output is shown 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 expects 640 KB of RAM is fitted.  A0000 hex = 640 KB.  If 640 KB is not fitted (motherboard and/or expansion card), the test will fail.
• The KEYBOARD CONTROLLER  test will fail if no XT-class keyboard is connected to the motherboard.
• The FLOPPY CONTROLLER  test requires that a floppy controller card is fitted to the 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 the motherboard's math coprocessor switch in the wrong position for that.
• The SLOW REFRESH TO A0000  test takes a few minutes to go through 640 KB of RAM.
• The MEMORY REFRESH  test may not reveal a memory refresh problem.


Other Notes:

• References to chips are for the corresponding chip on an IBM PC (IBM 5150) motherboard.  For example, the second test displays U33 SUPERSOFT ROM CHECKSUM  even though the BIOS ROM socket is not U33 on your clone motherboard.
• The term 'KEYBOARD CONTROLLER' can be misleading.  The vast majority of PC and XT clones do not have a keyboard controller chip on the motherboard, using discrete components 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.
• If you are using the Supersoft/Landmark Diagnostic ROM because the motherboard appears 'dead', and you have discovered that the Supersoft/Landmark Diagnostic ROM is running fine, then see note 2 below.


Images (content) to be programmed into EPROM

To create a Supersoft/Landmark ROM, you program/write ('burn') an image into a suitable EPROM.  An EPROM programmer is required to do that.  That EPROM replaces the motherboard's BIOS ROM.

There are some people/companies shown at here who can supply EPROM's, programmed/written ('burned') to your requirement.

Find out what EPROM type your PC/XT clone motherboard uses, then choose the appropriate image below.  As shown at here, by far, the most common EPROM type used on a PC/XT clone motherboard is 2764 (27C64).

Type of EPROM Size Image download   Comment
2764 (27C64) EPROM 8 KB  Download  
27128 (27C128) EPROM 16 KB  Download  8 KB image that has been doubled.
27256 (27C256) EPROM 32 KB  Download  16 KB image that has been doubled.   See note 1 below.





Note 1 Per here, a Winbond W27E257 can be used in place of a 27256 or 27C256.
   
   
Note 2 If the Supersoft/Landmark diagnostic ROM shows no problem, then the following possibilities exists:

• The BIOS ROM chip is faulty.

• There is an addressing problem in the RAM subsystem.
   The Supersoft/Landmark diagnostic ROM will not detect that.
   The RAM checking code in the POST will detect certain cases of addressing problems.
   To see if your motherboard is in this situation, use Ruud's Diagnostic ROM at here.  It will detect most RAM addressing problems.