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Tandy 1000 TL/2 with Issues

Gramcon said:
I tried adding a VGA card, a Trident TVGA8900D-R jumpered to work in an 8-bit slot. The machine doesn't even recognize the card, output still goes to the onboard video. I found another post on this forum from someone using this card in a TL/2, so I know it should work in this machine. I tested the card in 16-bit mode in a 486, so I know the card is not defective.

My last ditch effort (before attempting to de-solder and replace the onboard video memory) will be to populate the memory expansion slots and see what that does. For that, I will have to wait for memory to arrive from Poland. It was cheaper that way...
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I'm a 1000SX guy and have never played with TL - TL/2, so I might be sending you on a wild goose chase. Take a close look at your mobo and see if there is a video interrupt jumper somewhere near the expansion slots. On the 1000SX there is a dip switch (SW1) which enables/disables the on-board video. Worth a shot.
 
I'd hoped that was the case, but according to the oldskool guide, the TL's don't require setting any jumpers to add VGA, just plug in the card. I still played around with the VSYNC and IRQ jumpers, to no avail. :)
 
Gramcon said:
I'd hoped that was the case, but according to the oldskool guide, the TL's don't require setting any jumpers to add VGA, just plug in the card. I still played around with the VSYNC and IRQ jumpers, to no avail. :)
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I didn't look at the TL/2 guide, but the TL clearly shows a video interrupt jumper just to the left of the 1st expansion slot. I don't know the difference between the two.
 
Nah, I can't even get that far to change video modes with the keyboard. The instant I turn it on, I get the messed up screen, a faint "memory err info" visible through the mess of ASCII characters, and I can see some numbers cycling at the bottom (probably a RAM count), until I get a beep code (really fast, but it sounds like 4-3-1, RAM test address failure), then it hangs. I tried installing a known working VGA card, but when it is not detected at all, and changing interrupt jumpers on the motherboard doesn't do anything. From what previous replies have said, the best guess now is bad video RAM on the mainboard. What a shame they soldered this 128k in instead of socketing it like the rest. Anyway, I'm waiting for four 64k x 4 chips to arrive so I can populate the expansion slots, maybe move the video out of the bad RAM so I can get a display. This probably won't work, in which case I'll attempt to desolder the bad chips and replace them. I'll probably wreck the mainboard in the process, so I'm saving this for last.
 
Update:

Well, this is perplexing. I added the additional 128k of memory, and the machine counts 768K RAM and now boots without a memory error, but there are still weird graphical artifacts present with the onboard video (see picture 1). However, it's not as bad as before, and I can see the prompt...typing CLS clears some of the artifacts, but it's still messed up.

So then I try it with the VGA card again. Well, it appears to work fine, but looking closely, you can see some characters are not showing up (see picture 2). I tried multiple monitors with the VGA card, same thing.

Remember, before adding the 128k, the VGA card wouldn't detect at all, and the onboard video was still screwed up with artifacts but appeared to display a memory error in the background. This case continues to confuse me!

Picture 1.jpgPicture 2.jpg
 
Gramcon said:
Update:

Well, this is perplexing. I added the additional 128k of memory, and the machine counts 768K RAM and now boots without a memory error, but there are still weird graphical artifacts present with the onboard video (see picture 1). However, it's not as bad as before, and I can see the prompt...typing CLS clears some of the artifacts, but it's still messed up.
So then I try it with the VGA card again. Well, it appears to work fine, but looking closely, you can see some characters are not showing up (see picture 2). I tried multiple monitors with the VGA card, same thing.

Remember, before adding the 128k, the VGA card wouldn't detect at all, and the onboard video was still screwed up with artifacts but appeared to display a memory error in the background. This case continues to confuse me!

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Any way you can come up with another video card? You need to start eliminating components as source of the problem.
 
Well, it would require another trip to the 'bay. I'll have to hold out for a good deal -- I've already spent too much on this!
 
Gramcon said:
Well, it would require another trip to the 'bay. I'll have to hold out for a good deal -- I've already spent too much on this!
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Do you know someone close by that has an ISA PC that you might slip your card in to see how it works?
 
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