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Everything posted by LouisB

  1. Well, thanks to Nezgar sending me a few chips including this memory diagnostic utility, my 800XL is back in business! And memory looks good. Now for my next project :
  2. When I get the OS EPROMS from Nezgar I'll test everything out and report back. I'm assuming this is a Rambo flavor bank switcher. It took me awhile to get my head around the how, what and why of the memory upgrades, and this thread was extremely helpful and has it well in hand: I would also add this article does a nice job of visualizing what's going on with memory bank selection / switching, Figure 1: As for how the extra memory is leveraged, at first I thought that somehow the OS would transparently make it available to the system, but now I see that each individual program, demo or DOS has to be smart enough to access the various bank switching methods in order to leverage it? This thread covers some ground on that:
  3. Thanks for mentioning that, Sys-Check looks incredible (I watched this demo video) and it did come on my radar. I'm going to hold off for now but i'm keeping that option in my back pocket.
  4. Wow that's extremely generous of you! I'll PM you right now
  5. Thanks Nezgar, holding the option key takes me to an unresponsive blue screen with a cursor. Sometimes I can get to basic by turning it on, then holding option and hitting reset. When I type BYE I get a blue screen with a cursor. I can type commands but they're not processed when I hit enter. In the end I could not access the self-test screen by any means.
  6. To clarify, I start up the computer, I have to reset a few times to get the "Ready" prompt, then when I type "LIST" that's when I get the screen full of 0's. I waited awhile to see if it would stop, but seems to go on forever. Thanks again for the info guys, I did some homework on Atari OS's and piggyback mods. Next I have to dig into what a "Rambo" upgrade is and how it works. It's not clear to me at the moment if I simply have a configuration issue with this unit, or something is faulty and needs testing / clean / re-seat and verification as The Doctor pointed out. I'll keep working on it and report back.
  7. Ok - yes that's bad news, but makes sense because I couldn't find any signs of a solder connection to the motherboard anywhere on the front or back. I'll do some homework on memory upgrades, multi-OS mods and the like, thanks for helping me out on where to start. A Trak disk drive came with it, but I haven't been able to fire it up.
  8. Here are the rest of the images:
  9. Ah, OK. I see it's something like this:
  10. Ah, switch makes sense because there's a mysterious hole in the back next to the parallel bus. Do you know what the other end of the switch would connect to? Ground? Thanks for the tip I'll check the cartridge port for random things. I can tell you guys are knowledgeable, thanks for the quick responses.
  11. Hello, I recently purchased an 800XL and when I plugged it in and turned it on it did this: That was sort of odd to me. Sometimes I could get it to ready if I held down option and hit reset. I took it apart and found this: Does anyone have the foggiest what's going on here? I have to admit, I'm an 8-bit hardware hacker newbie (i'm more the programmer type) so this is going to take awhile for me to figure out. Thanks
  12. Sorry - I'm a 2600 programming newb - how would I compile and run this in an emulator? Maybe you could point me in the right direction? Thanks
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