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Ram chip location

Started by aje_fr, July 23, 2016, 09:45:28 AM

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Well, I don't like to register to a forum to request help, but it looks that this forum is the best place over internet (at least other than in japanese ) to get some help.
Few times ago I purchased a X68000 ACE, sold as is. I made all necessary interfaces to plug it on my TV (vga cable, PS2 keyboard, PS2 mouse), and... obviously, computer have problems...
Few pixels remains displayed on the right of the screen when in text mode.
I burn a floppy with mtest to check the ram and it looks that the text ram have problems (see attached picture).
Right now, I know that text ram chips are IC18->IC33, but I don't know wich one store E1FFFC:xxxxx8xx data.
Any help will be welcome (I don't want to remove all 16 chips ;-) )
Best regards


In the archives of this board there should be some schematics but I dont know if they label which ram chips correspond to which memory range.

We don't have anything ACE specific but it may be similar to the original model


Thanks for your answer.
I was almost sure this information was not available but before starting to remove components I prefered to ask.
So, I start to remove chip one by one, two by two, and four by four. And I finally repaired the computer.
My problem was either ic18,19,20,21, as I replaced all in one shot, I'm not sure wich one exactly.
I'm also surprised that some games were not booting properly with this deffect (rtype, pacmania), they were stuck on title screen, even if there were no need of this ram.
Maybe text ram was used as spare ram on some games ?
Right now, I have to find a 1meg extension to upgrade it to 2megs


R-Type uses TVRAM for the background scroll.