8b1f24c6   
   From: jkorman@alltel.net   
      
   On Wed, 4 Aug 2010 06:08:37 -0700 (PDT), Keith   
    wrote:   
      
   >Hi All,   
   >   
   >I am a collector of antique computers, and have recently acquired a   
   >TRS-80. It's just the base model, with a tape drive and monitor.   
   >   
   >I've noticed that the video displays incorrect characters; letters are   
   >switched, that sort of thing. It looks like bits are getting flipped   
   >in the video RAM, but unfortunately, I'm a little ignorant when it   
   >comes to TRS-80 hardware. I was wondering if anyone here has ever   
   >experienced this before, or if someone knows where I can go for   
   >replacement video RAM chips! I'm not decided whether or not it is the   
   >video RAM specifically; I suppose even a bad capacitor would be   
   >capable of causing such a bug. I'm a tad lost!   
   >   
   >The bug is pretty consistent; about 2/3 of the screen is covered in #   
   >marks, which leads me to believe the space character is getting   
   >flipped to something else in video RAM, but also leaves me thinking   
   >that some of the video RAM is still working (there are places where   
   >the space character shows up as a real empty space).   
   >   
   >I've also confirmed that the characters are being stored in system RAM   
   >correctly; I was able to write a simple BASIC program that caused an   
   >infinite loop that printed "HELLO" forever (although "HELLO" looked   
   >more like "HEVV5", or something to that effect).   
   >   
   >I appreciate your time. Thanks for your help!   
   >   
   >Keith   
   At first guess, based on the transposition in HELLO, I'm going to say   
   that the character generator ROM may be bad.   
      
   Jim   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)