PS/2 FAQ, Section 6

S) 6.0 Diagnostics 

Q) 6.1  What do the POST beeps mean? 

Beep(s)                  Errant device 
No beep                  Power supply, system board 
1 short beep             System OK 
2 short beeps            POST Error displayed on monitor 
Repeating short beeps    Power supply, system board 
3 long beeps             3270 keyboard card 
1 long, 1 short beeps    System board 
1 long, 2 short beeps    Display adapter (MDA, CGA) 
1 long, 3 short beeps    EGA 
Continuous beep          Power supply, system board 
 

Q) 6.2  What do the POST codes mean? 

Note if errors are encountered with the reference disk in the drive they will be identified.

See Appendix D for full listing.

Q) 6.2a  What do the CP codes mean? 

Wait! 04/24/00

Q) 6.3  Why when my system boots fine sometimes the diagnostics report errors?

This is usually a case of non-IBM components added to the system.  Some examples are video adapters, hard drive controllers, and the like.  In most cases, POST is always right and the reference disk is tricked into thinking there is a problem so don't have a heart attack when it gives you the: 'Replace system board' message it could just be a normal option generated error.  Also lock-ups are common with some video cards added to the system.
   For IML systems, a common problem is downlevel reference and diagnostics disks.The current refdisk and diags disk may have been used to update the system partition, but sometimes a outdated file remains. The system then has a mix of old code and new.
   For non-IBM adapters, no *.dgs files exist. That's why you NEVER see non-IBM adapters under "Run System Checkout". SCSI devices and memory use the IBM *.dgs files (so that's why you see them).

Q) 6.4  How can I *REALLY* find out if these errors are just bogus?

The *EASY* method if your system hangs on the full tests is to enter <CTRL>-A from the reference disk main menu and select the test it hung up on.  If everything checks out then no problem.

If you want it to run the full test without hanging the only method is to remove each card and reboot with the reference disk allow it to auto-configure and then reboot and run the reference disk tests.  If the system hangs now then there is a problem with the system not related to added options, contact IBM or a repair tech promptly and try not to use the machine until it is 
looked at.

Q) 6.5  OK I got a problem, who can I get to fix it?

Anyone know of a good repair facility???  They are all currently closed.

Q)  6.6  What are the wrap plugs the reference disk sometimes refers too?

In order to perform a total test of the ports (when running IBM diagnostics) you need to provide the incoming signals to the port via a wrap plug.  The constructions of each (serial and parallel) are listed below:
 

                     PARALLEL PORT WRAP PLUG

To construct this wrap plug use a DB25 male connector. (minimum 30AWG wire)

      pin   1  to  13
      pin   2  to  15
      pin  10  to  16
      pin  11  to  17
      pin  12  to  14

Then before running the diagnostics attach the DB25 to the parallel port.

                      SERIAL PORT WRAP PLUG

To construct this wrap plug use a standard RS232 DB25 female connector and wire these pins together.  (minimum of 30AWG wire).

Updated via Brian Lee (blee@fish.share.net) who read the IBM FAX page.

       pin  2  to   3
       pin  4  to   5
       pin  5  to   8
       pin  6  to  20
       pin 20  to  22

Then attach this to the serial port before running the diagnostics.

Please note I have not tested this on an actual PS/2, but this does work on standard ports and PS/2s don't have any propriety-type pins on the serial or parallel ports.  Can someone let me know if these are the right 'loops'?