From: Blackepyon01@yahoo.ca   
      
   On Thursday, 7 October 2021 at 17:44:50 UTC-7, butter...@gmail.com wrote:   
   > My Tandy 1000ex boots up great, outputs perfect video and audio, reads my   
   5.25'' floppies, and generally seems clean upon inspection, however, there   
   seems to be some issue with the key input.    
   >    
   > For example, in Boulder dash, the character is constantly moving left, and   
   in other text fields, a constant shift leftward is present, as if the left   
   arrow key is constantly being pressed. I disconnected the keyboard and the   
   issue remained, meaning the    
   Tandy thinks a key is always pressed, regardless of the presence of the   
   keyboard.    
   >    
   > I ordered a joystick adapter hoping to play without needing to worry about   
   the arrow keys at all, but I'm now wondering if the input of the joystick   
   totally overrides any previously present input (would the joystick cause the   
   Tandy to disregard the    
   constant left input?).    
   >    
   > Regardless, If anyone has any information as to what problem my Tandy 1000ex   
   is having or how to visually identify the problem on the motherboard it would   
   be great to hear it.   
      
   You can find the technical reference manual for the EX here: ftp   
   //ftp.oldskool.org/pub/tvdog/tandy1000/documents/extech.zip   
   Page 82 has the schematics for the keyboard controller. Check to see if   
   anything on the motherboard might be corroded or shorting around the 8048   
   microcontroller (U6, should be right next to the keyboard headers).   
      
   If the rest of the keys work, then I don't find it likely that the   
   microcontroller itself is hooped, but there's always the possibility.    
      
   On pages 134 & 135 are the keyboard mapping. Left arrow is B13 on the matrix,   
   which corresponds to shorting pin 4 on J1 with pin 19 on J2. Problem is that   
   these numbers correspond with the schematic for the mylar circuit in the   
   keyboard, and the    
   motherboard uses different numbers, so you'll have to figure out yourself   
   which pins on the 8048 those correspond with.    
      
   Hope that can get you started. Front and back pictures of the motherboard may   
   help. I've got an HX, but the layout of the motherboard is a bit different   
   from the EX, so I'm just going off what's in the tech reference manual.   
      
   --- SoupGate-Win32 v1.05   
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