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Atari 800 upgrade and modification blog

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M.D.Baker

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Atari 800 hacking, modding, upgrading
This blog is all about my adventures in modding my Atari 800. So far I have installed an Incognito board and a dual-Pokey upgrade (less the actual audio output). And I did some repairs on the keyboard and modified a shift key to be more balanced and sturdy by inserting and extra plunger and spring in an empty key spot below it. Hopefully this will solve a design problem that causes the plunger to crack and stop the new plunger from cracking in the outside corners that make the shift key bind.

As I've mentioned elsewhere before, all current and future upgrades and mods are from now on going to be installed by me using Dupont connectors as seen in the pictures below, and eventually I intend to retro-fit all my upgrades in this way, for easy removal and installation for trouble shooting.

Below are pictures of these installations. I had her back together already, but the keyboard didn't work, and after rechecking my dual Pokey installation, have come to the conclusion that I used a bad 74LS14 IC, and have now replaced it with a new 74HC14 and am about to power it up, after I finish this blog segment, and see if the keyboard works. The Incognito worked fine.

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Well, after months of postponing my 800 upgrades and mods, due to an unknown issue that turned out to be the keyboard, I'm back at it. The keyboard is yet to be fixed or replaced, but the project is moving forward without it for the time being.

So, after the successful incognito installation, the stereo upgrade was and is the next step, though the original plans for a DIY dual-Pokey have been changed to a Pokeymax Quad+covox audio upgrade. Quite a leap from just stereo, but I want the best.

The Pokeymax is plugged in the socket and is currently working as a standard Pokey until I get a couple of wires connected to the CPU and audio output with a simple pre-amp circuit to bring it up to line-level audio. I am also installing a second SIO port and due to the placement of these new I/O ports I am combining the Pokeymax audio out with the SIO out on the same circuit board.

So the first step on the new board was to attach the SIO connector (one of half a dozen new 3D printed ones I bought from The Brewing Academy) to the board and a cable to the new SIO port that is connected at the other end to the original SIO port, continuing the SIO daisy-chain internally in the 800. I went with shielded VGA cabling since I have plenty on hand and it's the best thing to use to ensure no interference in close proximity to the motherboard. The cable is directly soldered to the new SIO connector and it's board, but I installed Dupont connectors to the SIO port on the 800's PSU board for easy removal and installation in the future. I fanned out the pins on the back of the SIO so I had room to plug in the Dupont connectors with the capacitor for the PSU in the way.

The next step will be to install a headphone jack stereo audio out to the new circuit board and attach a wire harness to the Pokeymax that will run to the new board.


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Continuing the upgrades, I have now attached the wire harness to the Pokeymax, with three wires going to the CPU on the CPU board and three wires going to the SIO/Stereo out board. I used a headphone jack style stereo audio out so it would fit on the board with the SIO port, and both will fit nicely where I make cut-outs for them on the underside of the case, leading out the back left recessed area of the 800 case underside. Again I use DuPont connectors at the audio out for easy separation from the motherboard and CPU board. The only thing left for the Pokeymax upgrade is to make a spot for the audio out wires to go through the heavy shielding. I suppose I'll have to drill a hole through the shielding near the Pokeymax chip. And I just remembered I need to connect the headphone jack's ground to ground on the SIO connector which is connected to ground through the cable to the PSU to ensure proper grounding.

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Next will be S-video, composite and mono audio out board directly opposite the 2nd SIO/audio out board, it will be hidden underneath the PSU board and connected to the original monitor port in close proximity. Once that board is done, then I will cut out spots for all the new I/O connectors in the 800's bottom case, then mount the boards and I/O connectors.

As promised in the last paragraph, I've made a DIY S-video/Composite/mono audio out board. Like the second SIO, these are just direct lines from the nearby monitor jack. As per usual now, at least one end is attached with Dupont Connectors so that all upgrades and boards can be easily separated if need be. I had left/right audio jacks on hand, so the red one has been re-purposed for composite video (I only want this for NTSC high-res games for artifact colors).

The mono audio out is white. Instead of attaching a switch to one of the Pokeymax lines to change between mono and Quad-stereo out, I left it so Quad-stereo is always on as I will use the mono out for programs that don't use stereo. And of course, the main reason for the DIY mod board, is a real S-video jack. The S-video on both my Atari's gets fed through either video-to-VGA or video-to-HDMI outs and they don't make the adapters with separate chroma/luma lines. But my 1200XL uses a break-out-box for video which does have separate chroma/luma for when I get my CBM 1084S monitor repaired which does have these inputs. The 800 will always be connected to a converter.

But now, except for the power jack, I no longer have to have cables coming out the side of my 800 getting in my way on the desktop. All other I/O will now be discretely placed in the recesses on the underside of the 800 with all cables hidden and running out the back like XL/XE machines. Though I'm out of space there now, since the 800's motherboard fills the rest of the bottom case, my PBI and extra controller ports will have to be mounted to the rear left side of the 800 coming directly out of the back. So all that is left for these upgrades and mods is to cut port holes in the 800's case and mount the boards.


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Here are pictures of my two I/O boards mounted in the case. I used E6000 Industrial adhesive, which is like an epoxy, but remains slightly "rubbery," and after curing for 24 hours the boards will be completely secure. This was my final solution for my PBI in my 1200XL how it's mounted and is holding the PBI in place tight, for over two years with PBI devices plugged and unplugged over that time. The second photo, left to right are my new S-video, mono audio and composite video jacks. The third picture, left to right, SIO port and Pokeymax stereo audio out via mini phono jack.

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So what is left? Other upgrades/mods intended for the 800 are an internal Turbo Freezer (still waiting to arrive in the post) which will also serve as my PBI port out the back of the 800 using it's PBI pass-thru edge connector. Also Dual or possibly triple PIA board (waiting to arrive in the post) for the possibility of many more controller ports for my external projects. The final upgrade to the 800 will be a Sophia 2 board (waiting for it to be available). And, of course the keyboard will have to be repaired or replaced, but in the mean time, a TK-II PS/2 keyboard interface (waiting for it to arrive in the post) will be temporarily installed so I have a keyboard to use with the 800 until the original is back in place. Then I will call the modded 800 complete.

By the way, the keyboard has been repaired and now works perfectly!

Well, I've been continuing my 800 upgrades this week. The 800 has been converted to PAL, requirements were a PAL crystal on the motherboard, a PAL CPU board I have, and of course,.the Incognito can run on NTSC or PAL.

I've also upgraded the 800 with a PBI port. It was already upgraded with full PBI capabilities from the Incognito, but there is a 50-pin (SCSI?) style connector on it that is the gateway to PBI devices being connected. As with my DIY PBI upgrade on my 1200XL, I created and actual PBI edge-connector port on the rear of the 800. With the 1200XL, I salvaged parts from a 600XL for the mod/upgrade. With the 800 I was able to use the a XE ECI-to-PBI adapter that I don't need for an XE and never will, that came with my Turbo Freezer 2011. I still have to get the connector and 50-wire ribbon cable to connect to the Incognito and create the physical buss. On the 1200XL I purchased a length of 50-wire rainbow ribbon cable for it, and of course had to make all connections directly to the IC's, instead of a connector to plug in.

I also made an enclosure for the Turbo Freezer's PBI board, with a connector on it for the actual Turbo Freezer housed in a cartridge case. I just used an old, small, project box that has been laying around for years, the board didn't quite fit, so it has "wings" out the side, but I think it still looks better than a bare board, and I'll paint it to match the 800.

Anyway, here are some pictures and I'll go into more detail later.

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Pictures of the PBI upgrade continuing below, I'll write up more about it later, as well as above, when it's 100% done, I still have to install a SCSI male connector on the XE pass-thru PBI board so both ends of the cable can be unplugged for easy removal and installation.

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Two more upgrades will be the last upgrades for this 800, then I will consider it a completed project. The first is a Sophia 2 video board, which arrived a few days ago and I have finished installing it. Below are the pictures. Internally it's just a matter of removing the original GTIA IC and installing the Sophia 2 board in it's place, however, the Sophia 2 came with a precision socket, and although I could have just plugged it into the original socket, I decided to go with the recommendation of installing the precision socket So this involved a lot of de-soldering and soldering, but it was a success. I forgot to take a picture of the Sophia 2 board before I put the 800's shielding back on.

I had to cut a small rectangular area from the bottom of the 800's shielding, so the Sophia 's ribbon cable could pass through. I then had to cut a hole in the rear of the 800 to mount the DVI connector. due to a lack of room where I decided to install the DVI port, I installed it vertically so that it would bit between the motherboard's heavy shielding and the PSU board's heat sink.

As usual I connect the board to the inside of the case using my trusty E6000 industrial strength adhesive. Using the adhesive is quite a bit like using hot glue, minus the glue gun and it's about 1000 times as strong and is not easily removed by hand or fall off in time like hot glue does. But, it is still very easy to remove and clean up with a good razor knife. This allows me to add boards and connectors with no drilling holes and using screws or bolts so it is much less evasive and much quicker to do, except you need to wait 24 hours for full strength before you go applying pressure (like plugging in plugs).

Now all that is left is to plug the ribbon cable into the DVI board then plug in the Sophia 2 to a monitor. I don't have monitors with DVI, so I use a simple DVI to HDMI adapter plug. One last thing is to use the Sophia 2 setup software to choose a resolution and screen ratio. I will of course be using 4:3 screen ratio so the Atari screen looks as it should. This restricts me to one DVI resolution, 1024x960. This is fine as since the Atari's display is a maximum of 320x240, any DVI resolution (or VGA) is more than enough.

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The one upgrade left to come is a dual-PIA board to upgrade to 2 PIA's. An uncommon upgrade that probably 99.8% fo Atari users wouldn't care for (I only know of myself and @Graham who is designing the boards). I'll be using the second PIA to add more Atari controller ports so I'll have 6-8 controller ports (depending if I'm in 800 mode or XL/XE mode). My reason for wanting all these ports is strictly for connecting exterior projects to the Atari, the first being parts that will eventually become a robot with an 800 on board with the same PIA upgrade so there are enough lines to cover any control mechanisms I need for the robot. While building and testing my robot, it's extremities and sensors will be attached via AtariLab Interfaces and RCA cables. Once the robot is ready to be autonomous, the controller ports will use standard plugs connected to the robot instead of AtariLab Interfaces











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