Cheshire Noir

I use a modified Genesis controller for the Atari and Commodore systems. My approach was to cut around the internal controller, and then bridge from the pads to the wires directly. I connected button 2 and 3 to "up" and "down" respectively. (For the c64 I even added a second port connector wired to button 4. On the c64, the fire button on joystick 1 maps to an I/O port that also is used by the space bar. As most games use joystick 2, this means you can "press the space bar" on games like Commando, which throws a grenade) I have also made a custom one for my Amstrad CPC. It's my latest and neatest. I wrote it up here if you were interested in seeing how I did it. I might have to make me a joy2b+ joystick, now I know they exist. I do happen to have another clone Genesis controller I can use Cheers! Chesh,

Thanks for those. I'll fix those up and reload it up to the repository in the next few days. Been working on other systems today and yesterday. (Fixed my Creativision and made a brand new joystick for my Apple II) Chesh

OK I have put the board back in my system. Mind you it now looks like this: So considerably neater. I've also uploaded all my KiCAD stuff to my github: https://github.com/cheshirenoir/AtariMemEx It's the "final" version, as to do any more work, I'd need to open up the Atari again, and I just want to play some games for a bit. Pharaohs Curse, here I come! Thanks for everyone's help!

Hooboy. Glad you're checking. Basically I got chip 3 and 4 mixed up in a couple of places when plotting out chip 6. Working on a new version now.

Now I'm actually awake, rather than trying to dump a couple of hours tracing into the intarwubs in a hurry, I can go through this ? U5 pin 8 you are absolutely right. I drew a wire over another wire. I have corrected that. The wire from U6 pin 3 goes to U4 pin 3 but has been cut. (Cuts are marked as open jumpers) Wire 26 and 27 are soldered directly to U6 (now noted as JPatch). ClausB I hope this means something to you. I never got that far in logic. Also apologies for the very messy KiCAD drawings. I'll upload the original files when I get back from work. Chesh AMEMEX1.01.pdf

So I have traced it out. There are undoubtedly errors. I've checked it to the best of my ability. My next step is to refit it, and clean up as I go. Hopefully it'll all work at the end If anyone needs me to check anything, let me know by Friday night US time (My Saturday morning) Chesh AMEMEX.pdf

I've traced all the lines to / from two of the chips so far. It's a slow process but I'm hoping to have it fully traced out either tonight or tomorrow. I'll throw it in KiCAD once I'm done and post it here.

ClausB you are quite correct on it being a PAL system, and also on that chip being a 7474 series. I pulled the board out to clean it up and it's quite visible now. I tried desoldering the chips off the board but they're soldered from the top, not the bottom, except for ground and power rails. I couldn't budge them. I've cleaned up the soldering, and all the horrible double sided tape. I'll trace the traces if I get a chance, clean off the pad I accidently lifted, and then reinstall it, while cleaning up as much as I can. Hopefully it'll work when it all goes back together. If it doesn't I may try and return it to "stock" for now, until I can afford something more modern. On the bottom of the board is "© DM 1986". On the top is "1.2", if that helps anyone trying to guess the origin of the board. The board itself has two cut traces, so it's a modded mod I guess? Chesh

Starting with that board, the 6 chips on it are (from top left, clockwise) a 74174 (pin1 top right - Hex D FlipFlip), a 74173 (pin 1 bottom left - Quad D FlipFlop), two 74158s (pin1 top right - Quad 2 input multiplexers, inverted), a 7427 (pin1 top right - Tri NOR gate), and a 7432 (pin1 top right - Quad OR gate). It's a double sided board, which is adding a layer of complexity to my investigation, and it has components soldered to the underside ? I've started tracing it but it's gonna take a couple of days. VERY tempted to desolder it and clean it up. (Numbering guide for the rest of what I've found) R32, R104, R105 removed The hole for R32 east is connected to board pin 11 (Black wire) The hole for R104 north is connected to board pin 10 (blue) The hole for R105 north is connected to board pin 12 (orange) U27 pin 1 connected to board pin 7 (brown) U27 pin 8 connected to board pin 21 (white, labelled "-") <- this would make sense. Just tapping ground and +5v U27 pin 16 connected to board pin 22 (Yellow, labelled "+") U28 pin 2 connected to board pin 2 (Purple) U28 pin 5 connected to the switch (black wire) U28 pin 1 connected to U3 pin 4 (underside mod) U28 pin 4 connected to U28 pin 12 (underside mod) U28 pin 7 connected to U3 pin 5 (underside mod) U2 pin 9 connected to board pin 14 (yellow) U30 pin 13 connected to board pin 13 (grey) U19 pin 2 connected to board pin 17 (red) U19 pin 12 connected to board pin 20 (grey) U7 pin 19 connected to board pin 4 (yellow) U7 pin 20 connected to board pin 6 (white) U7 pin 25 connected to board pin 9 (purple) U7 pin 26 connected to board pin 8 (red) U7 pin 30 connected to board pin 16 (green) U7 pin 31connected to board pin 15 (white) U8 pin 35 connected to board pin 19 (blue) U8 pin 40 connected to board pin 18 (black) U23 pin 12 connected to board pin 3 (green) U23 pin 13 connected to board pin 5 (orange) U23 pin 14 connected to board pin 24 (white) U23 pin 15 connected to board pin 27 (red) U23 pin 16 connected to board pin 26 (yellow) Board pin 1 goes to the switch (black wire) Board pin 25 goes to board pin 23 (it's a bodge) (I initially thought there was a hack on u29 before I discovered it's supposed to look like that ) I haven't started investigating the chips on the Atari itself. I'll post more as more info comes to hand ? Chesh

Whoah. OK, the board is out for a protracted period anyway at the moment. (It keeps crashing when the system gets hot. My first step is to replace the ROM socket as it's been stretched to all sh*t by the old ROM tower) I'll trace all the pins and identify all the chips and write it up for you all. May only be of interest to a handful of people but what the hey ? Chesh

Cheers for that. That makes sense Chesh

Hey Folks, Sorry if you are sick to death of these already but... So my 800xl came with a RAM upgrade. Using eXtended RAM Test, I see 192k of RAM in 3 banks. Looking at the motherboard I see 8 x 41256 RAM modules. To me this suggests 64K of RAM is "missing". This machine is horribly bodged together, and I have already had to remove a ROM tower that seemed to be causing more problems than it's worth. So my questions are: Am I off the beaten track? Is my RAM upgrade only 192k? If it should be 256k, where on the board should I be looking for faults? Happy to pop the hood and photograph additional bits if it'll help. Long term I figure I'll source a modern RAM replacement and "undo" as much of this mod as I can, even if only for my own sanity. (BTW, the ROM tower only had MC Monitors, things that are of no interest to me. Are there alternative ROMs that are of use to have in an Atari 800xl, such as Diagnostics or additional functionality?) Cheers! Chesh

Cheers for all the replies! I stuck some black tape across the window seconds after taking that photo. Once I get the drive working (Just waiting for the final bits and pieces) I'll test that RAM. I dumped the ROMs and text in the ROM with "ULT1" on it suggests it's indeed ULTIROM. Text in the one with the window exposed suggests it's SUPERMON. I've attached all 3 if anyone wanted to poke around them. Thanks again, everyone! Chesh ULTIMON(3).BIN RAMROD(2).BIN SUPERMON(4).BIN

Hi There, I'm the proud owner of my first 8 Bit Atari system. I've never used any 8 Bit Atari systems before this. I purchased this system off EBay and it arrived on Monday. It's an 800xl at heart, but there's an additional rotary dial on the top right, and a bonus switch on the back right. It also has a Dymo label proclaiming it to be an Atari 260XE. The machine powers on and seems to run fine. The rotary dial seems primarily for changing between ROM images (More on that shortly) as the first position brings up a Machine Code Monitor. The other three positions bring up standard looking READY prompts in slightly different shades of Atari blue. Last night I finally opened it up and... Well let's just say it's exciting in there. There's a ROM tower to the right that was poking up through a hole cut in the RF shield and a board slap bang in the middle and about a million "bodge" wires running willy nilly, soldered directly onto various chips. (I have spotted the loose wire and will fix it tonight). There was also quite a lot of rust on the RF shield. The board looks fine. If I had to guess I'd say these are associated with a RAM upgrade. My questions are: Does anyone recognise these mods? Is there any way of finding out what's on the ROMs? (I have a TL866 II+ so I can pull them and read them if that would help) As I mentioned, I'm brand new to all this. Talk about diving in at the deep end I'm working on an SDMax so I hope that I'll be able to load software on shortly, which will give me access to more diagnostics. Thanks in advance! Chesh