Insert the POST-Probe into a PCI or ISA slot 
Power the system on. After a few moments, POST-Probe will display a 2 digit error code 
Simply look the code up in the documentation under the correct BIOS and you'll know why your system isn't booting! 

What our customers say:

"I'm in the PC repair trade and have not seen a tool this well thought out for many years." 
- Eric Fredericksen 

"We have been using Micro-Scope and POST-Probe for two months with great success. It really is as good as you have said in your publicity." 
- Digital 

Basic Post-Probe Info 

The usefulness of diagnostic software such as Micro-Scope fails at the point where the hardware problem is severe enough to prevent the system from booting up at all. At this point, the only way to pinpoint the failure is with a POST-code reader.

Theory of Operation

When a computer boots up, it starts by executing hard-wired instructions stored in the BIOS. These instructions do a check of the various essential machine functions, and then turn control of the system over to the boot loader routine stored on the hard drive. The series of instructions the BIOS does are called the Power-On Self Test, abbreviated POST.

At each step of the POST, the BIOS puts a code out on the bus. The original purpose of these codes was to allow the programmers to debug the BIOS program, but the codes are still present in the completed computer. 

A POST-code reader monitors these codes and displays them on a 2-digit readout that is called a hex display because it changes an electronic hexadecimal signal into a visual decimal number. Normally the codes change so fast they are just a blur, but if the BIOS fails to get past a particular point in the POST, the boot process will stop and the reader will display the code for the last step that was being attempted. That code will tell us what step the BIOS was unable to do.

If all BIOS manufacturers had used the same codes, it might be possible to memorize them. Unfortunately, not only do the codes differ from one maker to the next, but even from one version to the next for the same manufacturer. Therefore it is necessary to refer to a table listing the codes and their meaning for each BIOS being used.

The Post-Probe

The description given above applies to all post-reader cards, of which there are several. The Micro 2000 Post-Probe though is unique in several ways.

Both ISA and PCI connectors are available on the same card. All other post readers can be used in either the ISA bus or the PCI bus. This requires the field technician to carry two cards, or take a gamble on being able to use the right bus. 
The codes are displayed on both sides of the card. Some computers have the bus slots on a riser card rather than directly on the motherboard, which means the post reader could be upside down with the display hidden. Having a second display on the back side eliminates this problem. 
There is a stepping switch to retrieve the sequence of codes. If the BIOS is corrupt it can execute the instructions out of sequence, and the boot-up could fail for this reason rather than failure of the hardware indicated by the last code. This is nearly impossible to detect without the Post-Probe's stepping switch. 
A separate set of LEDs give a direct indication of several of the key bus signals and whether the power supply voltages are within tolerance, making it possible to diagnose many problems at a glance. 
The Manual

The Post-Probe comes with a 265-page spiral-bound manual, which in itself is part of the technician's troubleshooting arsenal. It has tables listing the post codes for over 60 BIOS versions, a list that includes every common BIOS and a few that most technicians will probably never see in their lifetime.

Each code also has a reference to the appropriate section of a diagnostic chapter, which explains the function in question, both in theory and in practical data on repair.

A separate chapter also has tables for the beep codes. These are audible codes that a number of BIOS versions use in addition to the post codes, with a unique pattern of beeps for different types of post failure. At the back of the manual is some reference material such as the standard IRQ assignments, standard adapter ROM memory allocations, and the bus pin-outs for both ISA and PCI.

How To Use It

Here is the complete sequence for using the Post-Probe to troubleshoot a non-booting system:

Turn off power and remove the case. 
Plug the Post-Probe into any vacant bus slot. 
Look on the motherboard and see what BIOS the machine is using, and find the table for that BIOS in the Post-Probe manual. 
Turn on the power. 
Read the code from the Post-Probe, then find that code in the table. 
Determine what part is failing. If needed, look up the indicated section in the diagnostic chapter of the manual. 
Turn off the power, and replace the failing part. 
Remove the Post-Probe and try booting again. 
 
 

1. Hex Code Display (ISA)  2. LED Signal Indicators (ISA) 3. Stepping Switch (ISA) 4. LED Voltage Indicators 5. LED Signal Indicators (PCI) 6. Stepping Switch (PCI) 7. Hex Code Display (PCI) 8. PCI Connector 9. ISA Connector

Minimum System Requirements 

ISA, EISA, or PCI Bus Slot

Product Includes

POST-Probe PCI Card
POST Code Booklet
Carrying Case 

Product Features 

UNIVERSAL CAPABILITIES - With the multitude of PCs on the market, the best way to be effective is to be universal. The Post-Probe PCI has a dual edge connector to work with either ISA OR PCI. The Post-Probe has the ability to function on various port addresses, depending on the bus type.

POWER SUPPLY MONITORING - 5 LEDs to monitor power supply. Also includes 4 voltage pads to test actual power under load with the use of a voltmeter (+5vdc, -5vdc, +12vdc, -12vdc). An extra LED has been added to monitor the 3.3v from the PCI bus.

CLOCK AND OSCILLATOR MONITORS - Another 2 LEDs monitor clock and oscillator signals, making it easy to determine synchronous operation. Additionally, the LEDs are on separate circuits, making it easier to spot the difference between clock chip and crystal failures.

RESET SIGNAL MONITOR - One LED monitors the Reset signal. This allows a reset to be seen during POST, which may indicate a short on the motherboard.

I/O READ & I/O WRITE MONITOR - Two LEDs monitor I/O Read and I/O Write, distinguishing between read and write failures. Also monitored are Memory Read/Write to distinguish between address line failures and memory chip failures. This feature is especially beneficial when working with older BIOSs that don’t emit POST codes, such as DTKs and older XTs.

HEXADECIMAL LED DISPLAYS - Hex display on each side provides improved visibility, regardless of slot orientation. 

COMPREHENSIVE MANUAL - Covers BIOS POST procedures for almost every PC on the market today including: AMI, Award, Zenith, Chips & Technologies, Hewlett-Packard, IBM, MR BIOS, Phoenix, XTs and DTKs. Each manufacturer’s POST list contains the test description and a reference to the Troubleshooting section of the manual. Detailed troubleshooting sections give details on prime components on the motherboard as well as their functions.