Supersoft/Landmark Diagnostic ROMs for IBM 5150/5155/5160/5170

Source: The ROMs and manual were supplied by Chuck(G) at the VCF


These are best described as ROM hosted motherboard diagnostics.

ROM HOSTED - Instead of the diagostics being on a floppy disk, or on a hard drive, they are on a ROM chip. You pull out the motherboard BIOS chip, and substitute the diagnostic ROM.
MOTHERBOARD DIAGNOSTICS - These are essentially, motherboard diagnostics - tests of the motherboard.

When to Use Them

Refer to the diagram at here. The diagnostics are good at detecting the situation where the motherboard's POST is actually starting, but failing on one of the very early tests, one where the POST gives no indication that the test failed.

I have seen these diagnostics do some weird things (example), some illogical things (examples), and sometimes present results that are completely misleading (example).
That said, these diagnostics have their place in the range of tools and procedures used to identify a problem cause.

Personally, there is only one scenario in which I would use these diagnostics:
* IBM 51xx motherboard that appears to be 'dead'; and
* I know that the motherboard has no short circuits on it (which would overload the power supply); and
* I know for fact that the power supply is good.

Just be aware that the weird/illogical/misleading things that I referred to earlier can lead you to incorrect deductions.


Be sure to connect up a speaker to your motherboard. Why? Because these diagnostics send error beeps to the speaker.
If the diagnostics have a problem initialising your video card, the error beeps will at least inform you that the diagnostics are running.
A description of the error beeps is in the user manual (link below).

Landmark and Supersoft

So, why does the user manual indicate "Landmark Research International" but the ROMs display "Supersoft Inc"? Easy. The Landmark company took over the Supersoft company.

User Manual

Click here for the user manual.


These diagnostics require a CGA or MDA/MGA video card. Not designed for EGA - EGA will display, but poorly.  Not designed for VGA.

Addresses shown on-screen are in hexidecimal and are absolute. Example: "10000" = 64K  (10000 hexidecimal --> 65536 decimal --> 64K)

ROM Images

These are images that you use with an EPROM programmer to create the diagnostic ROM/s.

Click here for the IBM 5150.
Click here for the IBM 5155.
Click here for the IBM 5160.
Click here for the IBM 5170.