jmunkki@hila.hut.fi (Juri Munkki) (06/24/91)
My Toby video card (old Apple card) just started acting as if something went wrong. I have to admit that I moved it to another slot and could have had a problem with static electricity, so I probably blew a chip somewhere. The card works fine in 1, 2 and 4 bit modes. In 8 bit mode, the bottom half of the screen has vertical stripes. The problem seems to affect only one bit out of 32. The third byte out of every four bytes looks as if it had value $F7 when it actually is $FF. Which chip should I change? (Why only one bit out of 32? Are the 8 chips all 4-bit wide, so that one data path is broken on one chip?) Looking with TMON Pro, the memory looks and acts ok, so I'm suspecting either the video controller itself or the shift register side of one of the VRAM chips. ____________________________________________________________________________ / Juri Munkki / Helsinki University of Technology / Wind / Project / / jmunkki@hut.fi / Computing Center Macintosh Support / Surf / STORM / ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~