Ways to identify missing ICs on an unknown board ?

marian

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I've got an old trainer made in USA by NUS Training Corporation :
MCT-8088PC Microcomputer Trainer (having an 8088 CPU)

for which i can't find any details on the net. Even the company who made is pretty much unknown.

It has the 10 missing ICs without any clue on what those were.

Are there ways that i can try to decode what those missing ICs could be ? They are spread across the board. It has a ROM that i can not identify either, but it is good at least.


thanks
 
Thanks. Yes, this is the one that i got.

You can see from the pictures all those missing IC's. Some of them might be not need it, but others looks like they were removed.

Its interesting to see that there is only this reference to this item and nothing else.
 
Probably was a pretty niche product, also one of a few players in the market, so no one has bothered to keep, or upload the doco.

Your best bet is to probably set up a global search in eBay and look for others that come up for sale, and hope they have decent photos. There isn't any easy way to find what should go in the sockets.

If the board is dusty one clue can be to look for sockets that are clean, meaning there was a chip in there once. This depends on when the chips were pulled and when it got dusty, but a very clean socket is a good clue something is missing.

The non-easy way to work it out is to reverse engineer the whole schematic and see what is missing. Any empty 20 pin sockets can be a worry as they are usually for PALs, so not only would you need a PAL, but you would need to know the logic that was programmed into it.
 
I assume this trainer was build to be used inside that company: NUS Training Corporation.
I've found some old videos about power plants hosted by this company.

The board is pretty clean.

First finding is that the power supply is completely dead. There are some small voltages 0.2 V instead of 5V and 0v on -12, -5 or 12V. Yes it has all this outputs.
When i open it inside, there were 2 screws laying around which probably might have shorted the power supply, if not already bad by some other reasons.

Just trying to power it up from another supply with 5V doesn't bring anything on the display. It looks that some of the missing IC are required at least for minimum function.

I haven't found any PAL on the board. It might be that there are none used at all. (i hope). That will be the best option i guess to see some other trainer like this showing up on ebay and hoping to get better pictures from there and figure out the missing IC.
 
Based on the photos, it looks like you might be missing an EPROM, which you're not going to be able to replace.

Maybe you can make some educated guesses using schems for other 8088/ISA PC clones?

Out of curiosity, why do you want to get this thing running?
 
Yes, i am hopping that the missing EPROM to be some extension which was never used.
On the existing one there is no letter/number to indicate others to be there.
If that's the one missing, i'll be stuck.

I am planning to get some guesses around the parts that have the missing IC. For example
there is one missing near the display/keyboard. (which might be a network resistor )

Good question about why i was trying to get it working.

Wanted to test my Fluke with the 8088 pod and this looked like a good exercise.

But now looks like a very complicated task due to missing IC, no details of any kind on this board and power supply also dead.
 
Yes, i am hopping that the missing EPROM to be some extension which was never used.
On the existing one there is no letter/number to indicate others to be there.
If that's the one missing, i'll be stuck.

I am planning to get some guesses around the parts that have the missing IC. For example
there is one missing near the display/keyboard. (which might be a network resistor )

Good question about why i was trying to get it working.

Wanted to test my Fluke with the 8088 pod and this looked like a good exercise.

But now looks like a very complicated task due to missing IC, no details of any kind on this board and power supply also dead.

Makes sense. You might consider building a board from a kit, there are several options for simple machines based on 70s/80s micros. ex. http://www.kswichit.com/8088kit/8088kit.htm, http://www.homebrew8088.com/, or you can even scratch build a whole PC XT clone: https://www.youtube.com/watch?time_continue=6&v=MW5lApN0gWc

Some trainer boards have switches to cause faults in various places, which you can then diagnose with your test equipment. Obviously none of these are going to have that, but maybe they'd work for your needs.
 
The name of the existing eprom is : NUSTC-MP-BIOS-2_09_89

That 2 might mean this is the second version or the second on the board. If the later then 1 eprom is gone and i'll be stuck without a monitor, unless i can reuse some from other trainers that was suggested. Or maybe some 8088 PC clones. The monitor is probably yo handle the rs232 and let you run some commands there.

Powering the board from an external 5V source, with internal one disconnected gets the voltages to around 3.7V.

This looks to be an issue on why the voltage drops to 3.7 from 5v. This is happening on all IC.
 
The name of the existing eprom is : NUSTC-MP-BIOS-2_09_89

That 2 might mean this is the second version or the second on the board. If the later then 1 eprom is gone and i'll be stuck without a monitor, unless i can reuse some from other trainers that was suggested. Or maybe some 8088 PC clones. The monitor is probably yo handle the rs232 and let you run some commands there.

Powering the board from an external 5V source, with internal one disconnected gets the voltages to around 3.7V.

This looks to be an issue on why the voltage drops to 3.7 from 5v. This is happening on all IC.

My guess would be that the BIOS was built on February 9th, 1989. Or September 2nd. The USA is stupid with our dates like that. YYYY-MM-DD for life.
 
yes, that was my first impression too looking at it.

For figuring out the voltage drop, i'll try to swap some of the IC and see if i can spot which one is causing this.

Otherwise, not sure how easy can be to find it.
 
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