Atari 800XL (pt1)

I have a real love of all things Atari, don’t know why, I never owned one as a kid. I already have a number of 2600’s which I play regularly. Push a cartridge in and off you go. The games may be limited, but they are great games. Recently, I have been investigating their other machines and came across an 800XL on Ebay that was in need of some love. After some reading, the 800 appears to have been well ahead of its time, the blocker to adoption seems to have been the price, which was close to $1000 in 1980. In terms of technology, it is comparable, if not better than the C64.

Atari 800XL

The EBay listing, for once, was honest and stated that it wasn’t working. When turned on you get random characters displayed on the screen. The machine had obviously been looked after with all of the chips in sockets – which has been done nicely, and the main chips have their name written on in pencil.

Atari 800XL motherboard

When turned on it responds to key presses, but the display is corrupted. With no previous 800 experience to go on I decided to test the RAM first using my tester…. all ok.

Testing the 800XL RAM

So, that’s as far as I have got so far…. my thinking is

  • It is executing code and responding to keypresses so the processor and Pocky are probably ok
  • It could be corrupt ROM? although I’m suprised that it’s getting so far is that is the case
  • One of the custom graphics chips is failing….

Testing the temperature of the chips, the CPU gets hot (normal) but interestingly the BASIC ROM also gets very hot…. could that cause these symptoms?