4-10 Maintenance and TroubleshootingBeep CodesDuring boot up, the computer performs a series of POST (Power On Self Test) routines. Abeep code may appear when an error is detected. There are fatal and nonfatal errors. Thefatal errors include BIOS, CMOS, DMA, RAM, video, and keyboard controller errors. Thenonfatal errors include timer tick interrupt, shutdown test, unexpected interrupt in protectedmode, gate A20, RAM test, interval timer channel 2 test, clock, serial and parallel port test,math co-processor, system board select, and extended CMOS RAM.The following table provides a description of the beep codes.Table 4-2 Beep Code DescriptionsBeeps Error Message Description1 Refresh Failure The memory refresh circuitry on the systemboard is faulty.2 Parity Error Parity error in the first 64 KB of memory.3 Base 64 KB Memory Failure Memory failure in the first 64 KB.4 Timer Not Operational Memory failure in the first 64 KB ofmemory, or Timer 1 on the system board isnot functioning.5 Processor Error The CPU on the system board generatedan error.6 8042 - Gate A20 Failure The keyboard controller (8042) may bebad. The BIOS cannot switch to protectedmode.7 Processor Exception InterruptErrorThe CPU generated an exception interrupt.8 Display Memory Read/Write Error The system graphics adapter is eithermissing or its memory is faulty. This is nota fatal error.9 ROM Checksum Error ROM checksum value does not match thevalue encoded in BIOS.10 CMOS Shutdown RegisterRead/Write ErrorThe shutdown register for CMOS RAMfailed.
