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Why Would You Do Diagnostics?

Diagnostics is one way to find a faulty part, or test a part to insure it is operational.

There are different ways to test a component:

  • Power it up
  • Run a rigorous testing program
  • Do a functional check

The first test you do on a daily basis or when you start your computer it is called a POST. That is Power On Self Test. This is a small program written in to the BIOS (Basic Input Output System) program that is part of the firmware on the motherboard of all computers.

The POST will do a investigative check for:

  • Processor
  • Processor cache
  • Memory
  • Memory Management Controller
  • Keyboard
  • Hard Drive Controller and Hard Drive(s)
  • USB Controller and attached devices
  • Video Controller
  • On older computers the serial and parallel ports

When you have a failure of a device or component from POST you will get either a beep code, a code on the monitor, or both. These come from the POST program and will be very cryptic because the program can only report failure of the test not the reason.

However you may want to run some further tests to insure that all components of a computer are working properly.

When I worked for a Computer Rental company all computers / peripherals were tested before going out for rental.

There are two types of testing programs:

  • Manufacture supplied Diagnostics

  • Third Party Diagnostics

The manufacture supplied testing may be a better choice for your computer because the programs are designed for that specific computer/device.

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Where as third party testing are designed for a broader range of computers/devices and will be more generic in nature.

Case in point:

I was experiencing a memory problem where at certain times my tower would BSOD, this problem came from two distinct devices. Using the manufacture's Windows testing program yielded bad results in that the testing said the computer had a bad memory module. However it did not tell me which module was bad. Nor did the testing detect the hard drive that was pending failure.

Knowing I had a bad memory module narrowed down the problem somewhat but still left me with a problem: Which memory module had failed? (There are four modules in the computer.)

By running the manufactures testing I still could not narrow the problem down to the specific memory module.

Now this may sound a little off but the reason the testing could not pin point the failed memory chip was because the testing runs in a Windows environment.

When I ran the memory test in DOS the testing pin pointed the failed memory module and the chip.

When running the tests in the Windows environment the memory address that was failing was locked out by the Operating System and the manufacture's testing could not test that area. Thus when the OS BSOD the actual error code was misleading, yes it was a memory error code but the code was pointing to the wrong memory address.

If you have a diagnostic program to test your computer components and it runs in the Windows environment take in to consideration that Windows does not allow direct access by user programs to the hardware, even if the manufacture's testing has special service drivers that load on startup.

How many times can you run hardware testing programs? As many times you want, when you start your computer the BIOS does it, the program is called POST (Power On Self Test). Testing each hardware component will not harm the hardware.

If you have an 'IT Toolbox' of programs to test computers I would suggest you get some low level programs that run in a 16 Bit environment such as DOS?  Smile

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Diagnostics is a special type of testing.

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