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Maintenance and Service Guide Compaq Presario 4900, 5000, & 5100 Series Computers
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Clearing CMOS
Power-On Self Test (POST)
Configuration
Diagnostic error codes
Troubleshooting without diagnostics
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> | TROUBLESHOOTING Power-On Self Test (POST) POST is a series of diagnostic tests that run automatically when the system is turned on. After the computer is turned on, POST checks the following assemblies to ensure that the computer system is properly functioning: Keyboard System board Memory modules Video memory Diskette drives Hard drive Power supply POST also detects the type of mass storage devices installed in the computer. If POST finds an error in the system, an error condition is indicated by an audible and/or visual message. The table below gives explanations of the error codes and a recommended course of action.
> NOTE: | An external speaker must be installed into the speaker output connector to hear audible beeps during POST.
Click a link below to find the probable cause and recommended action for a given error message.
Diskette Drive A or B Error | Keyboard Controller Error | System BIOS Shadowed
Extended RAM failed at offset nnn | Keyboard Error | System Cache Error
Failing Bits nnn | Operating System Not Found | System CMOS Checksum Bad
Fixed Disk 0 or 1 Failure | Parity Check 1 | System RAM Failed at Offset, nnn
Fixed Disk Controller Failure | Parity Check 2 | System Timer Error
Incorrect Drive A Type | Real Time Clock Error | UMB Upper Limit Segment Address nnn
Invalid NVRAM Media Type | System Battery is Dead | Video BIOS Shadowed
POST Messages
Error message | Probable Cause | Recommended Action
Diskette Drive A or B Error | Drive A: or B: is present, but fails the BIOS POST diskette tests | 1. Run Setup. 2. Replace the signal cables. 3. Replace the drive.
Extended RAM failed at offset nnn | Extended memory not working or not configured properly | 1. Replace the memory modules. 2. Replace the system board.
Failing Bits nnn | nnn is a map of the bits at the RAM address which failed the memory test | 1. Run Setup. 2. Replace the system board.
Fixed Disk 0 or 1 Failure | Hard drive is not working or not configured properly | 1. Run Setup. 2. Replace the signal cable. 3. Replace the hard drive.
Fixed Disk Controller Failure | Hard drive is not working or not configured properly | 1. Run Setup. 2. Replace the system board.
Incorrect Drive A Type | Type of diskette in drive A: not correctly identified | 1. Run Setup. 2. Replace the diskette drive.
Invalid NVRAM Media Type | Problem with NVRAM (CMOS) access | Replace the system board.
Keyboard Controller Error | Keyboard, I/O keyboard controller (on system board), or mouse error | 1. Replace the keyboard. 2. Replace the mouse. 3. Replace the system board.
Keyboard Error | Keyboard, I/O keyboard controller (on system board), or mouse error | 1. Replace the keyboard. 2. Replace the mouse. 3. Replace the system board.
Operating System Not Found | Operating system cannot be located on either drive A: or C: | Run Setup.
Parity Check 1 | Parity error found in the system bus | 1. Run Setup. 2. Replace the memory modules. 3. Replace the system board.
Parity Check 2 | Parity error found in the I/O bus | 1. Run Setup. 2. Replace the ISA board (modem).
Real Time Clock Error | Real-time clock fails BIOS test | Replace the system board.
System Battery is Dead | RTC battery is dead | 1. Replace the RTC battery. 2. Run Setup.
System BIOS Shadowed | System BIOS copied to Shadow RAM | Status message. No action required.
System Cache Error | RAM cache failed the BIOS test | Run Setup.
System CMOS Checksum Bad | CMOS is corrupted or modified incorrectly | Run Setup.
System RAM Failed at Offset, nnn | System RAM failed | Replace memory modules.
System Timer Error | DMA, timers, etc. | Replace the system board.
UMB Upper Limit Segment Address nnn | Displays the address nnn of the upper limit of Upper Memory Blocks, indicating released segments of the BIOS | Status message. No action required.
Video BIOS Shadowed | Video BIOS successfully copied to shadow RAM | Status message. No action required.
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