POST Probes -> Was -> Re: Here's a plan

[James Oakley]

Matthew Sullivan wrote:

> MicroPose (MicroProse?) - do the Micro2000, which is a rather useful
> POST probe.....
> 
> It's not cheap, but well worth it for the usefulness, it is listening
> address configurable, and will provide extra diagnostics like Osc check,
> clock check tri state logic probe, and of course all the voltages....

We *could* make our own. A POST card is an ultra-simple device, It
simply latches data from a specific port reserved for POST (I forget
which one off-hand though) and displays it via either a bank of 8 LEDs
in binary or two 7-segment LED displays in hex.

There are schematics in many electronic magazines (when Microcomputer
Journal was Computercraft, I believe they ran one, I think Popular
Electronics also ran one a while ago). I can search through all of my
old magazines to find the basic schematic.

We can add extra features as we wish, for example, a PIC could be thrown
on there to translate the data to a serial port (on the card, of course)
or to an LCD module with extra information. It doesn't matter that the
PIC is slower than the PC.

We could also add extra functionality such as a simple parallel i/o
port, i2c (which the PIC could handle nicely), analog switches, etc. We
could set it up to display POST codes on an LCD or LED module on the
front of the PC (it gets hard to read the display on a POST card if
other cards are blocking it).

We could even build a ROM programmer into it as an external module.

This is an easy design, even with all the extra features. I have an ISA
prototype card I can play with.

The most expensive part would be, of course, the PCB (I paid CAN$50 for
my prototype card) but if a bunch  of us wanted to make some (I have
many friends who would be interested in such a device, parallel ports
tend to run out quickly) we could get away with some relatively cheap
PCBs if we find the right place (I hear ExpressPCB is pretty cheap).

If anyone's interested (we *will* need post cards, especially for
debugging purposes), respond. It would also be nice to have a ROM burner
on it as I'm sure we will all need one of those as well.

James Oakley
jfunk at roadrunner.nf.net