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Supersoft/Landmark Diagnostic ROM
suitable for the 256KB-640KB version of IBM 5160 (IBM XT)motherboard



  WARNING:
The Supersoft/Landmark Diagnostic ROM is not known to detect RAM addressing problems.

( The POST in the IBM BIOS detects some. )
( For PC's and XT's, Ruud's Diagnostic ROM detects most. )


Version 1.2

This is the PC and XT version of the diagnostic, intended for the IBM 5150 (IBM PC), IBM 5160 (IBM XT), and clones.  Clone suitability will depend on how close the clone is to the aforementioned IBM computers.

An example output is shown at here.


The 256-640KB version of IBM 5160 motherboard has two banks of 256 KB and two banks of 64 KB.

Bank 0: 256 KB sized,  addressed 00000 to 0FFFF hex  (    0 KB to 256 KB)   (socketed)
Bank 1: 256 KB sized,  addressed 40000 to 7FFFF hex  (256 KB to 512 KB)   (socketed)
Bank 2: 64 KB sized,  addressed 80000 to 907FF hex  (512 KB to 578 KB)   (socketed)
Bank 3: 64 KB sized,  addressed 90800 to ‭9FFFF‬ hex  (578 KB to 640 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.



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 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.
• The MEMORY REFRESH  test may not reveal a memory refresh problem - see here.


Other Notes:

• Make sure that the two RAM switches in SW1 are set according to how banks of motherboard RAM that you have populated.  This is because, on the IBM 5160 (but not the IBM 5150), the two RAM switches in SW1 selectively disable/enable the motherboard RAM banks.  Note that per above, the diagnostics are expecting 640 KB of RAM to be fitted in the computer.
• On the 256KB-640KB motherboard, the 16K CRITICAL MEMORY REGION test needs only motherboard bank 0 to be populated.
• On the 256KB-640KB motherboard, the MEMORY REFRESH test needs only motherboard bank 0 to be populated.
• 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.
• If you are using the Supersoft/Landmark Diagnostic ROM because the IBM 5160 appears 'dead', and you have discovered that the Supersoft/Landmark Diagnostic ROM is running fine, then see note 3 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 BIOS ROM in IC socket U18.

As shown in the table below, you have the choice of using either a 27C256 EPROM (or 27256), or using a W27E257 EEPROM.

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


Type of EPROM for IBM 5160 Size Image download      Comment
27256/27C256 EPROM 32 KB  Download  See note 1 below.
W27E257 EEPROM 32 KB  Download  See notes 1 and 2 below.




Note 1 The Supersoft/Landmark ROM for the PC and XT is actually only 8 KB in size.
To create a 32 KB sized image, the 8 KB image was simply quadrupled.
Therefore, the 32 KB sized image contains 4 instances of Supersoft/Landmark ROM code.
When the 32 KB sized EPROM is placed in socket U18, it will be the fourth instance that gets executed.  (The first three are not used at all.)
   
Note 2 Regarding the programming/writing of an image into the W27E257:
Even though the W27E257 is an EEPROM, rather than a 'traditional' EPROM, you will still need an EPROM programmer (or other) to program/write to the W27E257.
That is because the IBM 5160 motherboard does not support programming/writing to EEPROM's in its sockets.
   
   
Note 3 If the Supersoft/Landmark diagnostic ROM shows no problem, then the following possibilities exists:

• The IBM BIOS ROM chip is faulty.

• There is an addressing problems in the RAM.
   The Supersoft/Landmark diagnostic ROM will not detect that.
   The RAM checking code in the POST of IBM 5160 BIOS will detect certain cases of addressing problems.
   To see if your IBM 5160 is in this situation, use Ruud's Diagnostic ROM at here.  It will detect most RAM addressing problems.