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Building the POST Code Project

WARNING: This section documents hardware MODIFICATIONS! Neither I, other contributors, or FreeBSD take any responsibility for ANY DAMAGE resulting from the use or mis-use of any information found on these pages! If you don't understand any of the following DON'T attempt to do it!

Modifying the POST Card

The modifications to the POST card consist of adding a 2nd male DB-15 connector to the back bracket. Unfortunately the card places the existing DB-15 connector in the middle of the bracket, so room for the 2nd DB-15 is tight. You might consider using a round high-density connector if you can find something appropriate.

Building the Remote Box

The remote box will contain 3 switches, 3 LEDS, 2 7-segment LEDs and a speaker. Note that both aluminum panels have a protective white covering on one side. Make your layout marks on this side, and remove the covering after all tooling is finished.

Building the cable

The cable between the POST card and the remote box consists of 2 DB-15 IDC female connectors on each end of either 1 30/34 conductor ribbon cable, or 2 15 conductor cables. Be sure to maintains pin-1 to pin-1 associations at each point in the chain.

Test and Final Assembly

Use an ohm meter to check the integrity of all wiring, from the berg connectors at one end to the LEDs/switches/sockets on the other. Once you are sure everything is OK, move the 7-segment LEDs from the POST card to the remote box.

Place the POST card into the computer. Replace the cabinet connectors with those from the modified POST card as appropriate. I set the switches up (from left to right) as Soft-power (red) , RESET (yellow) & NMI (orange). After final safety inspection power the computer up, either from the main power switch (AT) or with the remote box soft-power switch (ATX). Be prepared for an immediate powerdown at any sign of trouble.

Test the RESET switch several times (before the system can boot the OS). If all goes well boot single user and test the NMI switch. If ddb is installed it should drop you into the debugger. Note that the NMI code is NOT set up to expect this sort of behaviour yet, it assummes that NMI is a hardware failure, and that you wont be bouncing right back to the OS again! It might work, but its never been tested in this manner yet...

Observe any activity LEDs you hooked up. If they are not lighting up when expected its probably a simple matter of changing the polarity on the MB connection (ie. flip the berg connector around 180'). Finally you can test the 7-segment LEDs with testpost.c, available elsewhere on this page.

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