
   POST Diagnostic Beep Codes for XT/AT Computers
----------------------------------------------------
The codes are shown as a-b-c where 2-2-1 represents
2 beeps - pause - 2 beeps - 1 beep



Fatal Errors
------------

 1 - 1 - 3  CMOS failure
 1 - 1 - 4  Bios Checksum failure
 1 - 2 - 1  8253 Timer failure
 1 - 2 - 2  DMA setup failure
 1 - 2 - 3  DMA page register failure
 1 - 3 - 1  RAM refresh not verified
 1 - 3 - 3  Low 64K RAM failure
 1 - 3 - 4  Low 64K RAM even/odd failure
 1 - 4 - 1  Low 64K RAM address line failure
 1 - 4 - 2  Low 64K RAM parity error
 2 - 1 - 1  Low 64K RAM Bit 0 error
 2 - 1 - 2  Low 64K RAM Bit 1 error
 2 - 1 - 3  Low 64K RAM Bit 2 error
 2 - 1 - 4  Low 64K RAM Bit 3 error
 2 - 2 - 1  Low 64K RAM Bit 4 error
 2 - 2 - 2  Low 64K RAM Bit 5 error
 2 - 2 - 3  Low 64K RAM Bit 6 error
 2 - 2 - 4  Low 64K RAM Bit 7 error
 2 - 3 - 1  Low 64K RAM Bit 8 error
 2 - 3 - 2  Low 64K RAM Bit 9 error
 2 - 3 - 3  Low 64K RAM Bit 10 error
 2 - 3 - 4  Low 64K RAM Bit 11 error
 2 - 4 - 1  Low 64K RAM Bit 12 error
 2 - 4 - 2  Low 64K RAM Bit 13 error
 2 - 4 - 3  Low 64K RAM Bit 14 error
 2 - 4 - 4  Low 64K RAM Bit 15 error
 3 - 1 - 1  DMA #2 register error
 3 - 1 - 2  DMA #1 register error
 3 - 1 - 3  8259 #1 error
 3 - 1 - 4  8259 #2 error
 3 - 2 - 4  8042 KB Controller error
 3 - 3 - 4  Video initialization error
 3 - 4 - 1  Video retrace failure
 3 - 4 - 2  Video ROM scan in progress
 3 - 4 - 3  Video ROM scan error



Non-Fatal Errors
--------------

 4 - 2 - 1  8253 Timer tick test
 4 - 2 - 2  Shutdown/Restart sequence
 4 - 2 - 3  Gate A20 failure
 4 - 2 - 4  Unexpected Virtual Mode interrupt
 4 - 3 - 1  RAM Test in progress
 4 - 3 - 3  8253 Timer Channel 2 test
 4 - 3 - 4  Time of Day Clock test
 4 - 4 - 1  Serial Port test
 4 - 4 - 2  Parallel Port test
 4 - 4 - 3  Coprocessor test
