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IBM PS/2 Display Adapter bad RAM chip?

romanon

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Hello, i finally obtained this card, but it looks like there is some error with RAM.
Can we determine which chip is faulty from this results? Its from CheckIt program.

96da7d63d3f009916c24a61bf06a9460 (1).jpg
 

modem7

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That looks suspiciously like the false errors reported by CheckIt when CheckIt is run against a partially populated IBM EGA card. See [here].
Maybe that version of CheckIt also falsely reports errors against the IBM PS/2 Display Adapter.
What version of CheckIt are you using ?
Someone on these forums with an IBM PS/2 Display Adapter may be interested to see if CheckIt reports the same errors to them.

I expect that there are some IBM authored PS/2 diagnostics that also check the IBM PS/2 Display Adapter. Do they report a problem ?
 

romanon

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I know false errors reported by CheckIt when there is IBM EGA with less than 256k installed, but in my opinion, this is because CheckIt suppose that all EGAs must have 256k of video RAM. I tried other nonIBM VGA with 256k of RAM and no errors detected.
IBM PS2 Video Adapter also shows errors with imaging of some graphical modes, which is Checkit trying to show. That is imho proof of not only "false alarm" of Checkit program. BTW i am using version 4.0.
 

Xacalite

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BTW i am using version 4.0.
There was Checkit 4.0 ???
AFAIK the last original Checkit version was 3.0, and the next was Checkit Pro 1.0
Well, once I saw something identifying itself as "Checkit 5.0", but turned out to be fake.
 

romanon

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DITTO -- it's actually 3.0 hacked to report it's 4.1.

Ok thats not actually our main problem :)
I have news here, my friend have three this cards (!!) and he did the CheckIt test.
Guess what?
Same results as mine card. So why is CheckIt reporting these errors? Whats difference between nonIBM 256k VGA and this card?

Here are results of friends card
WhatsApp Image 2018-11-17 at 20.35.22.jpg
 

Xacalite

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What computer are you testing that card in?
It's designed for pre-PS/2 IBM PCs, and possibly for low-end PS/2s with MCGA.
It may exhibit problems in later machines.
 

romanon

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What computer are you testing that card in?
It's designed for pre-PS/2 IBM PCs, and possibly for low-end PS/2s with MCGA.
It may exhibit problems in later machines.

First computer was 386 machine. It starts with 1 long and 3 short beeps (graphics card problem)
Then I tried on my IBM XT-286 machine. Without beeps but with same errors on Checkit.
 

romanon

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Ok this is even more crazy than everything else....
All my test which I done before, was on B/W VGA monitor. I tried connect COLOR VGA monitor and? YES, memory test passed.
Only one fail i noticed. Mode 0Fh (EGA mono) is not working, there is only black screen, i tried two color VGA monitors, same results..

So, any explanation?
 

Xacalite

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Standard VGA monitors report to the card whether they are color or mono, so it's perfectly normal that the card behaves differently, ie. enables/disables grayscale mode.
But I have no idea why would it affect memory test.

As for the lack of 0Fh - it may be normal, I encountered something like this with some clone card, though I'm not sure exactly which mode was affected, might have been 07h and/or 0Fh, definitely some "mono" mode.
 

romanon

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Yeah, and its interesting also this fact. I started computer with color monitor, so graphics card received info, that there is color monitor installed. After that I connected BW monitor and all tests passed.
 

Xacalite

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You may also want to try enabling/disabling grayscale mode - I believe this is what true VGA cards do when they detect mono/color monitor:
Code:
INT 10 - VIDEO - ALTERNATE FUNCTION SELECT (VGA, MCGA) - GRAY-SCALE SUMMING
        AH = 12h
        BL = 33h
        AL = new state
            00h enable gray scale summing
            01h disable gray scale summing
Return: AL = 12h if function supported
Desc:   specify whether or not colors should be converted to gray scale when
          palette or color registers are loaded
 
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