Error Messages
When you run a test group or subtest in the diagnostics, error messages may result. These particular error mes- sages are not covered in this guide because the errors that generate these messages can be resolved only with a technician’s assistance. Record the messages on a copy of the Diagnostics Checklist found in Chapter 5, and read that chapter for instructions on obtaining technical assistance.
RAM Test Group
The RAM test group subtests check all the directly addressable RAM.
Why Run a RAM Test?
Faulty memory can cause a variety of problems that may not, at first glance, appear to be happening in RAM. If the computer is displaying one or more of the following symptoms, run both the subtests in the RAM test group to verify that the memory is not at fault:
•A program is not running as usual, or a proven piece of software appears to malfunction and you confirm that the software itself is not at fault. (You can con- firm that the software is functioning properly by moving it to another computer and running it there.)
•The computer periodically locks up (becomes un- usable and must be rebooted), especially at different places and times in different programs.
Subtests
Two subtests are available for RAM: the Quick Test and the Comprehensive Test. The Quick Test performs an address check to determine whether the computer is properly setting and clearing individual bits in RAM, and whether the RAM read and write operations are affecting more than one memory address location at one time. This subtest checks all available RAM. The Comprehensive Test also performs an address check, as well as the following:
•Data pattern checks, to look for RAM bits that are stuck high or low,
some data pattern problems that are internal to the memory chips
•A parity check that verifies the ability of the memory subsystem to detect errors
•A refresh check, to verify that the dynamic RAM (DRAM) is being recharged properly
System Set Test Group
The subtests in the System Set test group check the com- puter’s basic system board components and verify their related functions.
Why Run a System Set Test?
The System Set subtests
The System Set test group also verifies the proper opera- tion of other computer components, such as the speaker, that are not tested elsewhere in the diagnostics.
The following symptoms usually suggest a problem with a component or subassembly that warrants running a Sys- tem Set subtest:
•A program is not running as usual, or a proven piece of software appears to malfunction and you confirm that the software itself is not at fault. (You can con- firm that the software is functioning properly by moving it to another computer and running it there.)
•A PC Card you previously accessed can no longer be accessed.
•The computer periodically locks up, especially at different places and times in different programs.
•Parity errors or page fault failures (any error mes- sage that contains the word parity or page fault) occur at any time during operation. These errors are usually accompanied by a reference to an address, which you should record on a copy of the Diagnos- tics Checklist found in Chapter 5.