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Got a Unicron from ebay. Initially I could not get any video upon power up. After testing the power supply, cables, and the voltage regulator successfully, I decided to fiddle with the pot on the RF modulator with my hex screwdriver. It started to turn and I did get some video but now it broke and released this graphite-looking pieces. I don't think it turns anymore. What is the most logical course of action here? Is there an easy fix for this pot? Or do I go with composite mod knowing that the machine is working? This is the only reference I could find online regarding modding a unicorn. https://theokoulis.com/index.php/2018/09/27/the-unicorn/ Ps. I was hoping it landed on a different frequency around channels 2 and 3 but reprogramming TV did not work.

I now have, in my possession, a system that is not supposed to still be in one piece: A GRiDCASE 1537, a variant of the GRiDCASE 15xx series that has a substantial amount of shielding designed explicitly to minimize radio frequency emissions that could be intercepted ostensibly by bad actors. It was a system that was not sold to the general public, and was only available through GRiD's government services shell company, GSCS, and only if you had permission to acquire a unit from the appropriate superior. I'd only seen vague mentions of this unit in GRiD sales literature, as case studies. Because these systems were designed for classified information processing, they were supposed to be destroyed upon decommission. A few of these wound up as surplus, and somehow survived. By all accounts, there are, maybe, 5 of these left in the world. Which is why I was _VERY_ surprised, when on a lark, I typed in GRiDCASE, hoping to find a 1520 or 1530 to be used as a development testing unit for my PLATOTERM development, and I find somebody selling a 1537 TEMPEST for $1100. My eyeballs popped out of my head. As it had happened, I had recently sold a bunch of excess hardware and software via eBay, so I had some extra cash, and after a lot of gnashing of my teeth, I decided to pull the trigger. Now, what one of these units was doing on eBay, is strange enough. The fact that this unit was in Pervouralsk; a remote part of Russia, is truly one of life's great mysteries. -------- A bit about the unit: The outside: The case of the unit is black painted magnesium, with a rough matte finish, which, while not scratch resistant, is _extremely fingerprint resistant, as well as fending off some liquid spills. It is NOT waterproof, however. The whole thing is black. black as black can get. It looks like the tycho monolith, very intimidating and imposing. This is what you would imagine a spy to have and use. It is a clamshell design, GRiD pioneered the entire clamshell computer design with the Compass, and they extended it here with a larger screen, adding an internal floppy and/or hard disk, as well as a battery in most configurations, to make it a self contained portable. This specific TEMPEST configuration does not have a battery though, due to various requirements for processing classified data. Instead, the battery compartment is filled with a 16 volt DC-DC transformer, which is bolted into the chassis. A fan is added to this DC-DC supply (unlike most GRiDCASE machines) -------- The inside: This laptop was produced for roughly two years, starting in 1991. This was a beast of a laptop by 1991 standards: * 80386SX 20mhz, which can be upgraded to an 80486SLC. (I did this on my original 1530 I once had) * 4 megabytes of RAM * 120 megabyte Conner mil-spec hard drive. (Only 5 specific hard drive models can go into this unit, period.) * Chips&Technologies chipset and VGA (C&T 455), which can do 640x480x16 * Electroluminescent Display panel (ELD), with a characteristic bright yellow self-illuminating glow, the EL display has a quirk in that it only displays 640x400 in VGA mode, the bottom 80 pixels are cut off * 77 key mechanical keyboard (yeah, it's a fully mechanical keyboard) * 3.5 inch 1.44mb floppy * built in SCSI adaptor All for a cool price of approximately $13,940 in this configuration, which for the US Govt is...a bargain. ------ A bit about the TEMPESTing: The laptop is TEMPEST certified, this means that there has been a substantial amount of EM shielding added to the unit. There is shielding around: * The power supply * The display and its driver circuitry * the motherboard, which has a few bits of sub-shielding around critical parts, such as the processor and memory. * There is shielding around the floppy drive * There is also shielding around the hard drive * There is shielding around the connectors on the back, as well as individual sub-shielding for certain connectors (the keyboard and VGA) * Every interconnect is surrounded by braid shielding * The display interconnect also has two long iron toroids surrounding the braid. * There is a sensor attached to the hard drive tray, which detects if a hard disk is in the cradle, and therefore if tempest integrity is maintained. If the bay is open, the computer displays a warning indicating the tempest integrity can not be maintained. My sensor is malfunctioning, so i always see this message, my system boots anyway. ------ Here are some pictures of the unit in action, in its new life: https://imgur.com/gallery/WCO1sIZ -Thom

I would like your help to make something awesome that we all can enjoy. Here's the PURPOSE and POINT - - The original ATARI 2600 had a spot on the motherboard where a built-in game was SUPPOSED to be installed: Basically, that was a spot where an integrated circuit ROM (Read Only Memory) with a game on it, just like what you find in a cartridge, could be built-in. Somewhere during production of the ATARI 2600, however, that AWESOME idea was scrapped, but the "solder pad" for the game remained behind. Then, in later revisions of the motherboard that location was removed entirely. It is only found in "Light" and "Heavy" six-switch ATARI 2600 units. You can still install a game in that spot, though, and have it run automatically when no cartridge is loaded! There are some limits and challenges, however. Over the years, others have documented there observations and efforts to make this work, but to date no one has written a CLEAR, SIMPLE tutorial on how it can be done so others can enjoy it. (I reference the work of others that I could find in more detail, below) I'd like to change that, and I would propose that those who have something to CONTRIBUTE help write a definitive guide to make this work! Here's my PROPOSAL - - So far I've worked on this for a few weeks. I have gotten it to function - - to a point! I have major questions that are still unanswered, but I have done a lot of the first steps. 1) I would like to spell out below in tutorial format below what I have done so far. 2) And, I'd like to outline the MAJOR QUESTIONS that I think remain in order to get it to work properly What I'd like YOU to do, if you are willing, is tackle any and all of the parts or answer questions that you feel you can CLEARLY and POSITIVELY contribute to! What's that mean? It means that a "drive-by spray posting" of a few phrases with no illustrations or explanation, like "well, you just tie such and such to this and that, and there you go!" are not what we're looking for. This is for "the record," so it needs to be easy to read, and people have to be able to follow the steps again. Try reading some of these "BACKGROUND" threads below, and you will see what I mean . . . ### BACKGROUND There are several historic threads on the topic that provide some starting point for us. The first is the work of AtariAge member "Longhorn Engineer" along with user "A.J. Franzman" - - http://www.atariage....ost__p__1301781 Take a minute and scroll through it if you would like, but to summarize, there was a lot of back and forth on what was needed to be modified or added to the motherboard, some initial versions were tried with some success, and then it was abandoned. No real agreement on what you do or do not modify was reached. Honestly, that was the best thread I have found so far after a fair bit of searching. One other thread I found mentions the topic, along with a brief discussion of how to get larger games to work in that spot on the motherboard, but again no specifics are provided on how to DO it - - http://www.atariage....ost__p__2113348 There is a quick mention of the "unicorn board" ATARI 2600 Jrs. in that last thread link I provided, where the "built-in" game made a brief manufacturing resurgence - - http://www.atariage....ost__p__2113944 These are rare and not in every ATARI 2600 Jr. (don't start tearing yours apart!). Some of the "features" of this board work quite well, like accommodating larger built-in games. I have one of these boards and have gotten it to work with a built-in game (I chose PITFALL!), as I start to detail here - - http://www.atariage....-compatibility/ And, other topics can be found about "unicorn boards" as well - - http://www.atariage....2600jr-unicorn/ http://www.atariage....-unique-2600jr/ It's relevant because some of the "switching circuitry" that allows this to work in these late-model ATARI could be useful for this project. [Do you have other links or references for this section? Contribute them if you do, please!] ### QUESTIONS Some of these questions won't make sense until you start reading the outline of the TUTORIAL below but it's good to get them out here first, I think. There are just THREE main questions right now: - How SPECIFICALLY (what is soldered where and why) is it possible to get games larger than 2k to work in the solder spot? I have installed several 2k size games into the spot on a Light sixer, and had them work (COMBAT, etc.) but anything larger, like DONKEY KONG, will not work. As mentioned above, "A.J. Franzman" alludes that it is possible (http://www.atariage....ost__p__2113348), but there are no details. I can tell you that a 4k game DOES work in the "unicorn" - - PITFALL! is 4k, and I was able to get DONKEY KONG to work, too. - What is the BEST way (again, with as much detail as possible with what gets modified or added and why!) to get maximum compatibility for the detecting and automatic switching of a cartridge being loaded? I am pleased to say that by just straight installing a 2k ROM integrated circuit in the solder spot and doing NOTHING else, you actually get a LOT of compatibility. The console will automatically switch to the loaded cartridge in many situations. But not all. I have not figured out a pattern. Here's an interesting list of games that DID boot and work with the built-in ROM in place (non-scientific, I was just grabbing carts from a box) - - KEYSTONE KAPERS, DECATHALON, YARS' REVENGE, PRESSURE COOKER, COMBAT, FROGGER, WIZARD OF WOR And, those that did not - - GRAVITAR (you see the title screen, and then it rolls and glitches out), SPACE SHUTTLE, PITFALL II, and the HARMONY CARTRIDGE The HARMONY is a known case, and is likely fixable, by the way - - http://www.atariage....70#entry1943270 But, I have tried shorting those two pins that were mentioned, and still can't get it to work. Once the ROM is pulled from the motherboard, ALL of the above games will work just fine, including the HARMONY, by the way. - What is the cleanest and most direct way (once more, with DETAIL on exactly what to cut and solder!) to wire in a "kill switch" for when the above "compatibility mods" don't always work? We need a way to absolutely and positively disable the on-board built-in ROM for times where you want to return the console to its native state. I have looked and looked, and I just don't understand enough about disabling ATARI mask ROMs. I think it will involve cutting some traces that go to the place where ROM is located on the motherboard, wiring some pins of the ROM to be able to be grounded (or electrified?), and putting a positive switch in there somewhere that gets flipped. Any and all ideas on this one are welcome! ### TUTORIAL This will be short and sweet - - the steps thus far are simple! Take apart your sixer and expose the motherboard. I used this light sixer, with this serial number, and a manufacturing date of August 14, 1980 - - Ugh, this one was kind of gross before it got cleaned, and someone had kludged in a random non-ATARI cable - - Here is the motherboard and revision number - - And, as shown before, the solder spot - - I simply cleaned the solder holes with soldering braid, and then soldered in an integrated circuit socket - - IMPORTANT - - note that the socket is BACKWARDS the way I installed it! The "key notch" that shows you which way to orient the integrated circuit when you socket it in is reversed! I learned this because on the UNDERSIDE of the motherboard is a VERY small "1" etched into the traces that tells you where the first pin of the integrated circuit should go - - Look in the upper left hand corner, near my "1" that is drawn in marker (IGNORE my wire coming off the pin in this picture, it's something I was doing for testing) Now, in order to install your ROM, I recommend you actually place it in ANOTHER socket, and you will be socketing THAT socket into the one that is soldered on the board. I do this so I can have some modularity with my ROMs, and swap and try different ones. Here's how that looks - - I actually place a dot of solder at each of the four corners of the socketed ROM so that it doesn't come back out, too. If you are swapping these things in and out of the motherboard, it can happen, so this just secures it. What ROM to use? Right now there is a 2k ROM size LIMIT! If we can figure it out, the maximum size is 4k. No bankswitching or fancy special chip ROMs will be possible. EEPROMs are possible with the inclusion of an inverter [This is a section that needs to have more input on exactly WHERE and how an inverter would be placed to allow for an EEPROM] How do you know? I used Kevin Horton's excellent list of cartridges and scanned down it for 2k ROMs - - http://www.emulatron...tari8/sizes.txt (direct link) Which was found here - - http://emu-docs.org/...=All%20Consoles NOTE: desoldering ROMs from cartridges is slow and laborious. Desolder EVERYTHING completely though, and go slow so that you don't hurt the pins on the ROM! And, once you have your ROM and have socketed it, then you can place it on the board. NOTE the proper direction and orientation of the "key notch" here, which is facing RIGHT! - - DO NOT press down all the way with your socketed ROM! Just enough to make contact is for testing is perfect! If you press it in all the way, it's going to be HARD to get it back out without possibly bending pins! Once you are certain the project is done, you can "click" it positively in, however. And, that's it. Really. Turn on the console with no cartridge in it, and COMBAT or whatever will boot. Put a game in the cartridge slot and it will likely boot - - depending on the game. Now, there was a lot of talk in that thread referenced above about cutting ground traces, adding in a zener diode, and other "pull up circuits." I tried all that. I also tried it all WITHOUT it. So far, it works the same EITHER WAY, compatibility bugs and all. (note my zener diode and the cut trace on the ground, just like "Longhorn Engineer" had) Now I have repaired the cut trace, and removed the zener diode - - and I have the same exact compatibility as I did before. This is how it is operating now. I think that the "answers" to some of the compatibility questions and the kill switch idea will require cutting traces, but for now, this "works" without it. ### SO, that's where I am at. Still with me? tl;dr ? (too long; didn't read?) I'm looking forward to any and all ideas that people have. I will happily cut and solder whatever, as long as there seems to be a decent reason behind it, so please feel free to make suggestions! -atari2atari

Hello! I just posted a LONG, DETAILED thread in the hardware section about using the built-in ROM spot on heavy and light sixers - - http://www.atariage.com/forums/topic/196567-lets-improve-on-this-lightheavy-sixer-atari-2600-wbuilt-in-gamesrom/ It's text heavy, and quite geeky, but has the potential to be very cool! If you want to contribute, or are just curious, head on over and check it out . . . Thanks! -a2a