Atari 800XL: Restoration Part 2

I previously left my Atari 800XL with a faulty GTIA chip which completely broke the video output from the Atari. Now the restoration continues.

New GTIA

After asking around a few people suggested that I contact Best Electronics in America. They have an incredible selection of Atari custom ICs, including the GTIA I need. I could not source one anywhere else in the world.

They were happy to sell to me, but I had to make a $50 minimum order and use a US -> UK shipping service. So, I ended up ordering three GTIA chips (I’ll sell the spares) and used MyUS to ship them to the UK.

They arrived pretty quickly and I popped one into the Atari.

Testing

In theory, the Atari should be good now. So, let’s power it up and see what happens.

I’m pretty sure that is normal, let’s run some more tests.

You can’t hear a picture, but trust me, the audio was working fine. All the tests pass. It looks like the Atari itself is working well now.

Something Fishy

I checked the remaining new GTIAs in the Backbit Chip Tester, and they also failed. But when I tested them in the Atari, they worked fine. I then put the original back in the Atari, and that started working!

So, all this effort to purchase the GTIAs was for nothing, I didn’t need one. I have no idea what was originally wrong with the machine, maybe a dodgy socket, but it all works perfectly now with the original chip.

I reached out to Evie, who developed the chip tester. She immediately gave me some debug firmware and was able to spot the flaw in the test. This has subsequently been fixed in a firmware update. It turns out the test needs to be slightly different for PAL GTIAs compared to the NTSC ones.

Next Year

As we are reaching the end of 2023 and I’m writing this closing part on a tablet in a cabin in the woods, I’m not going to be doing any more restoration for the last week of 2023. In 2024 I was to try a game or two out on this machine, as well as attempt to at least get the disk drive up and running. I have higher priority machines to work on first, but there will be updates.