https://goto10.substack.com/p/800xl-inside [https] Goto 10 SubscribeSign in Share this post Inside the Atari 800XL goto10.substack.com Copy link Twitter Facebook Email Inside the Atari 800XL Paul Lefebvre 2 [https] May 20 Although I now have an Atari 800XL, it is not the one I had as a kid. This one is a later model because it has the Rev. C BASIC built-in. It is not modified in any way. If you zoom in on the picture below a bit, you'll notice the Option key is somewhat worn out. This is pretty common because you have to hold down Option to disable the built-in BASIC, which is usually needed when running disk-based machine language games. It really should not be necessary to do that since an ML game can disable BASIC itself, but it seems most didn't know that was a thing at the time. Otherwise, the computer is in good shape and the coloring is fine. It's perhaps not quite as white as it would have been originally, but it's not bad. The keyboard works great. [https] I took everything apart a while ago to clean it, so here is a quick look at its insides: [https] Going from left to right, you can see: * The RAM chips, 64K in total. There are 8 chips, so [S:each chip contains 8K:S] 64K, but only 1 bit. To get a byte, one bit is read from each chip. * The GTIA chip or George's Television Interface Adapter controls how the Atari talks to the TV. * ANTIC, one of the most famous Atari chips, was responsible for sending display information to the GTIA. * The 6502 CPU running at 1.8Mhz. You can tell by all the lines running to it from the parallel bus port at the top. * The Pot Keyboard IC or POKEY chip handles controllers, IO and sound. That it why you hear those beeping noises when loading files from cassette or disk. * The OS ROMs are next, which are 16K. * And lastly is the BASIC ROM (8K), which is Rev. C as mentioned above. * Edit: The chip in the bottom right is the PIA(Peripheral Interface Adapter), which handles the joystick ports. This is a pretty straightforward design, overall. Apparently my 800XL is one of the many (most?) that do not have the chroma line hooked up for monitor output, at least based on my testing. I need to do more research to see what it would take to fix that. I'm not big on soldering, but if this is easy enough perhaps I'll give it a try. If anyone has information on this they'd like to point me towards, I'd appreciate it. Thanks for reading Goto 10! Subscribe for free to receive new posts and support my work. [ ]Subscribe 2 Share [https] [ ] Create your profile [ ] Your name[ ]Your bio[ ] [ ][ ] Subscribe to the newsletter 0 subscriptions will be displayed on your profile (edit) Skip for now Save & Post Comment Only paid subscribers can comment on this post Already a paid subscriber? Sign in Check your email For your security, we need to re-authenticate you. Click the link we sent to , or click here to sign in. Roger Lacey 4 hr agoLiked by Paul Lefebvre Thank you for the article. I am also just getting back into Atari computing. I still have my Atari 800XL bought from Dixons with a 1050 disk drive back in the early 90's. I have bought a Meanwell 5V 15W substitute PSU for the 800XL as the original is about 30 years old. Incidentally, the 6502C processor is Atari specific and designated Sally. It has a HALT line which a normal 6502 CPU [https] does not so they are not interchangeble. Atari Age has an article on the S-Video modification for the 800XL at https://atariage.com/forums/topic/ 41580-quick-easy-video-upgrade-for-800xl/#comments. I have not tried this yet as I have been upgrading memory on my Atari 65XE as lots of programs require 320KB, especially if you look for them! Expand full comment Reply 1 reply by Paul Lefebvre 1 more comments... TopNewCommunity No posts Ready for more? [ ]Subscribe (c) 2022 Paul Lefebvre Privacy [?] Terms [?] Collection notice Publish on Substack Get the app Substack is the home for great writing This site requires JavaScript to run correctly. Please turn on JavaScript or unblock scripts