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IBM 5160  -  POST  -  Some errors


POST = Power-On Self Test


IMPORTANT:  The following is specific to the IBM 5160 (IBM XT).
  Certain portions will not be applicable to clones that were made of the IBM 5160.


Error      Description
[ Nothing ]
There a few motherboard tests that the POST does early, and if they fail, the POST simply halts the CPU.
This is unfortunate, because it results in the 'motherboard appears to be dead' symptom, a symptom that has many causes.

In the 5160, one of these early POST tests is a test of the first 16K of RAM (later revisions of BIOS test 64K).

If you believe that your motherboard is starting, and that one of the early POST tests is failing, then I advise you to try the Supersoft/Landmark diagnostic ROMs.
Note however, that there is no point in trying the Supersoft/Landmark diagnostic ROMs if the power supply outputs (
voltage and POWER GOOD signal) are incorrect.
 
1 long beep then 1 short beep
Two causes:
• The POST's test of the motherboard's 8259 chip (includes supporting chips) failed.
• The POST's test of the motherboard's 8253 chip (includes supporting chips) failed.
 
1 long beep then 2 short beeps
Some causes:
• 5160 motherboard - Configured via SW1 for an MDA video card, but either the POST cannot find an MDA video card to initialise, or the MDA card is faulty.
• 5160 motherboard - Configured via SW1 for an CGA video card, but either the POST cannot find an CGA video card to initialise, or the CGA card is faulty.
• A video card with a BIOS expansion ROM did a self test and found a problem with itself.
 
1 long beep then 3 short beeps
The BIOS expansion ROM on an IBM EGA card is known to generate this if it discovers that the card has faulty RAM.
 
201   displayed on-screen

(xxxxx  xx  201)

RAM related error.
For the 5160, the 201 will be prefixed by an address and a byte (e.g. "30000 10 201").

Some possible 201 causes:
• 5160 motherboard - RAM failure.
• 5160 motherboard - incorrect switch settings.
• RAM expansion card - failure of its RAM or circuitry.
• RAM expansion card - incorrect switch settings.

More information at here
 
301   displayed on-screen

(301)
(xx  301)

Keyboard related error.

If the "301" is preceeded by a byte, e.g. "23 301", then the keyboard's self test is indicating to the POST that a key is 'stuck' down. The byte indicates which key (see here).

If the "301" is not preceeded by a byte, then it's a general keyboard error.
Possible causes:
• AT class keyboard attached. That will not work. A PC/XT class keyboard is required.
• Keyboard accidentally attached to cassette connector instead of keyboard connector.
• No keyboard attached.
• Faulty keyboard - broken wire in cable.
• Faulty keyboard - wire loose in connector.
• Faulty keyboard - chip failure.
• Faulty motherboard - bad solder joint on keyboard connector.
• Faulty motherboard - faulty keyboard circuitry.
 
601   displayed on-screen
Test of floppy drive 0 (DOS refers to this as A:) failed.

Some possible 601 causes:
• Floppy controller card - faulty.
• Floppy controller card - dirty edge connectors.
• Floppy cable - faulty.
• Floppy cable - not the correct type for a 5160 - see here.
• Floppy cable - not fitted correctly.
• Floppy drive - faulty.
• Floppy drive - drive select jumper not set properly - see here.
• Floppy drive - not configured correctly for a 5160.
 
1701   displayed on-screen
This error is not generated by the motherboard's POST, but by the initialisation code within a BIOS expansion ROM residing on an XT-class hard disk controller.

1701 is a very high level error, indicating a problem with the hard drive system (system = controller + cables + drive + configuration + power).
So, lots of possible causes.
 
1801   displayed on-screen
The POST found an extender card for the IBM 5161 Expansion Unit within the 5160.
Because of that, the POST made an assumption that a 5161 Expansion Unit is connected to the card.
The POST attempted to communicate with the 5161 and that communication failed.

Some possible 1801 causes:
• 5161 Expansion Unit is not connected to the extender card.
• 5161 Expansion Unit not powered on (needs to be powered on before the 5160 is).
• Faulty extender card.
• Faulty cable.
• Faulty 5161 Expansion Unit.
 
C8000 ROM   displayed on-screen
An expansion card has a BIOS expansion ROM addressed at C8000, and that ROM is faulty or corrupt.
C8000 is commonly used by XT-class hard disk controllers.
 
CA000 ROM   displayed on-screen
An expansion card has a BIOS expansion ROM addressed at CA000, and that ROM is faulty or corrupt.
CA000 is commonly used by third-party floppy controllers (those that have a BIOS expansion ROM).
 
D0000 ROM   displayed on-screen
An expansion card has a BIOS expansion ROM addressed at D0000, and that ROM is faulty or corrupt.
 
F6000 ROM   displayed on-screen
Motherboard ROM chip U19 is faulty or corrupt.  See note 1 below.
 
F8000 ROM   displayed on-screen
Motherboard ROM chip U18 is faulty or corrupt.  See note 1 below.
 
FA000 ROM   displayed on-screen
Motherboard ROM chip U18 is faulty or corrupt.  See note 1 below.
 
FC000 ROM   displayed on-screen
Motherboard ROM chip U18 is faulty or corrupt.  See note 1 below.
 




Note 1 Only the 11/08/82 BIOS generates this error.
In later revisions of the BIOS, the POST checks U18 and U19 very early, and if U18 or U19 are found faulty, the POST simply halts the CPU.