CharlesMouse

Hi atari8warez, Thanks for the reply. A fair point, that would be rather embarrassing for me! I assumed it would be ok as this upgrade is advertised for the XE too... With hindsight socketing the headers would have been a good idea, but as I intended this upgrade to be permanent and I wasn't expecting trouble. (famous last words!) Further findings that may help those more familiar with these machines than me. Field Service Manual: Page 25 - 'Red/Brown Screen U2-5, 18, 19, 28, 30 Isolate and replace defective IC' U2 - HD74LS138p Hmm, maybe I fried it? I probably have the odd 74HC138 laying about - are they interchangeable on the 800XL? The rest don't look immediately obvious candidates: U3 - MMU Replaced by upgrade... U4 - Basic ROM Fried? Doubt it, and would a dead BASIC ROM prevent boot-up with said expansion in place? U5 - OS ROM Replaced by upgrade... U18 - DM74LS08N Can't see how I'd kill that. But if so, again, will the 800XL tolerate an HC part? U19 - Not present on this board revision. U28 - D4050BC on my board. For motherboard memory, I assume. Replaced by upgrade anyway..? U30 - Not present on this board revision.

Hello all, I never owned an 8-bit Atari back in the day, but being a bit of a retro-enthusiast / occasional hardware modder I thought 'Its about time I got in to this Atari thing.' (This could be a looong first post. While searching the forum I may have missed obvious answers to my problem(s), apologies.) Well, I was most pleased to recently get my hands on an 800XL, even more pleased to see what good shape it was in (once I'd given it a good spruce-up), then delighted to discover it's an XL-F. I've yet to work out if that really is much of a good thing, but lurking on various Atari forums has given me the impression it might be... ...well, after playing for a bit (I really must make up a proper video cable - I'd quite forgotten how awful RF can be) time for my real interest in old computers: fiddling... ...not being at all familiar with these machines to get my feet wet I went for some pre-made boards in the shape of an Ultimate 1Mb, among other goodies. ... Sadly I seem to have killed my new baby already, and insufficient knowledge of these machines has left me without much clue. Rather than the READY prompt (or what one would expect from the Ultimate 1Mb on first boot) I'm getting a blank dark brown screen with a reddish tinge to it - yes, I followed the instructions carefully on Lotharek's website, and did the Reset-Help thing on first boot, as instructed... ...I've carefully checked all my soldering to make sure all is good, and rechecked ribbon cables are the right way round, and re-rechecked my connections from Sally to P2 are correct - It's interesting that the few photos of this mod I've turned up seem to show P2 connections to the edge connector rather than the CPU - I guess shorter cable runs are always a good thing, if you know where to pick up the relevant lines. (I stuck to the instructions on the above website) Ok, so what next..? As everything, except FREDDY, was soldered in on my motherboard I hot-aired out the MMU and OS ROM (I don't like cutting IC's just in case I need them again). Having tracked down a schematic for the XLF I have now replaced C25, C26, C49 just in case I roasted the poor old things a bit too much - I haven't, as yet, replaced the caps near the OS ROM as that part of the board's a bit more open, so hopefully less potential for cooking components... ...I didn't socket the headers (to reduce opportunities for poor connections) so I can't easily return it to stock to see if it works without the Ultimate 1Mb. Ho-hum... I'd really appreciate some thoughts - Thank you! Photos: Not amazing quality I'm afriad, but just in case they prove useful. 1_800XLF 2_MMU CloseUp 3_OSROM_CloseUp 4_800XLF_1Mb 5_800XLF_1Mb_Unplugged I can do better once I've reclaimed my good camera from my daughter...