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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 and XTRAMTEST should detect 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.  The variation between clones is so much, that I cannot instruct you as to which chip on the motherboard is the BIOS ROM, nor what EPROM type to use for the image.

What I can say is, most of the 'cheap Tiawonese' motherboards, based on an ERSO design, use a single 2764 (or 27C64) EPROM.  I have some of those, and the W27E257 EEPROM option shown below, works for me.

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

Type of EPROM EPROM
size		 Qty. Image download   Comment
2764 (27C64) EPROM 8 KB   1 Download  
27128 (27C128) EPROM 16 KB   1 Download  8 KB image that has been doubled.
 "   "   "   "   "  16 KB   2 Download  Odd/even (high/low) pair of ROM's
27256 (27C256) EPROM 32 KB   1 Download  16 KB image that has been doubled.   See note 1 below.
W27E257 EEPROM 32 KB   1 Download  16 KB image that has been doubled.   See note 3 below.





Note 1 Per here, a Winbond W27E257 is expected to work 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 is not known to detect addressing problems.
   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 and XTRAMTEST at here.  They should detect most RAM addressing problems.
   
Note 3 Regarding the programming/writing of an image into the W27E257:
Even though the W27E257 is an EEPROM, rather than a 'traditional' EPROM, you will probably still need an EPROM programmer (or other) to program/write to the W27E257.
That is because it is highly unlikely that the motherboard of a PC clone or XT clone supports programming/writing to EEPROM's in its sockets.