31336haxx0r Posted January 5, 2013 Share Posted January 5, 2013 Hi fellows, I have a spare 800 XL PAL board around. Yesterday I thought: "Hey, what if you mod this into a PAL 5200?" Probably it's a dumb idea, as the software for the 5200 is written for NTSC. Also, I have no idea where to start for a mod. Could it be as easy as remapping all the memory mapped devices? Quote Link to comment Share on other sites More sharing options...
+Allan Posted January 5, 2013 Share Posted January 5, 2013 Your better off starting with a 4-port NTSC 5200 since they were designed to be converted to either tv signal. There are also about three PAL versions of 5200 games. I know one was Missile Command. Allan Quote Link to comment Share on other sites More sharing options...
31336haxx0r Posted January 5, 2013 Author Share Posted January 5, 2013 Let the hunt for a 5200 begin... Quote Link to comment Share on other sites More sharing options...
Rybags Posted January 5, 2013 Share Posted January 5, 2013 Pal/NTSC differences would matter as much as the computer, ie practically no problem other than speed difference. But I believe the kicker is that there is region checking and if carts have a certain bitsetting then won't work on Pal. If you went to the trouble of converting a computer into 5200 though, making a hacked OS would be the least of your worries. It'd be an interesting project, but the complexity would be even greater than something like Incognito for the 800. Memory mapping issues aside, you'd need to setup the controller ports which in itself would be a heap of wiring. In theory it might be possible to make a custom ribbon that went into the keyboard slot to cover most. Given the small catalog and fact almost all 5200 games are on the computer anyway though, the demand for a near ready made project to convert the computer to a 5200 wouldn't be too big. A happy medium might be to make an interface that allowed using 5200 controllers on the computer, then it'd be a case of patching existing games to work with it. Quote Link to comment Share on other sites More sharing options...
31336haxx0r Posted January 5, 2013 Author Share Posted January 5, 2013 Oh my god, the wiring nightmare. I hate to have a bazillion of wires dangling around, waiting to get soldered to the right spot. Been there too often while wiring up custom made wiring looms for engine and ECU swapped cars. It would be a nice project, but I'm afraid it's somewhat too big for my expertise. Quote Link to comment Share on other sites More sharing options...
+Mitch Posted January 5, 2013 Share Posted January 5, 2013 Your better off starting with a 4-port NTSC 5200 since they were designed to be converted to either tv signal. There are also about three PAL versions of 5200 games. I know one was Missile Command. Allan I thought it was the 2 port that had the spots for converting it to PAL? Mitch Quote Link to comment Share on other sites More sharing options...
GroovyBee Posted January 5, 2013 Share Posted January 5, 2013 31336haxx0r would be better with an AV modded 5200 and a different PSU (to avoid the need for a step down transformer). Then the colours will be right on a PAL60 TV. Quote Link to comment Share on other sites More sharing options...
31336haxx0r Posted January 5, 2013 Author Share Posted January 5, 2013 That is most likely the best choice. Quote Link to comment Share on other sites More sharing options...
+Allan Posted January 5, 2013 Share Posted January 5, 2013 I thought it was the 2 port that had the spots for converting it to PAL? Mitch You might be right. Was going by memory which isn't always right. Allan Quote Link to comment Share on other sites More sharing options...
slampam Posted January 6, 2013 Share Posted January 6, 2013 Curt released pics of the 5200 PAL schematics. But IIRC they were too low-res to read. Quote Link to comment Share on other sites More sharing options...
Vic George 2K3 Posted January 6, 2013 Share Posted January 6, 2013 I'd rather see like a dual 5200/XL game machine that could run either system's games by just plugging in the cartridges. 1 Quote Link to comment Share on other sites More sharing options...
Rybags Posted January 7, 2013 Share Posted January 7, 2013 Even the cartridge interface is a problem in itself - obvious mechanical difference aside, the computer only presents 16K of the address space but 5200 allows for 32K. Any solution be a spagetti of wires or if a plugin board be expensive and complex. Atari 800 would probably be the host of choice insofar that minimal modifications vs others would be needed. The cartridge addressability could be provided by a Ram board. Possibly an alternate CPU board could be devised which allows for both address decode schemes. Probably easier to just provide a second Pokey for the 5200s audio and I/O faciiltiies. But still, you'd be looking at 2 or 3 boards + alternate cart and controller ports and a bunch of wiring, quite possible at 3 times what you'd pay for a 5200 machine. Quote Link to comment Share on other sites More sharing options...
ClausB Posted January 11, 2013 Share Posted January 11, 2013 Interesting idea. It could be done neatly, without spaghetti. You would need to mod three areas: 1. Decoders: Remove MMU PAL and '138 and replace with '139 and 10 short wires. 2. Controllers: Build adapter cables from 9-pin to 15-pin for analog stick and trigger buttons. A few cuts and jumpers to the keyboard decoder circuit to emulate keypads with the keyboard. 3. Cartridge: Build adapter board from 30-pin to 36-pin and add one wire for A13. Quote Link to comment Share on other sites More sharing options...
Innovative Leisure Posted January 11, 2013 Share Posted January 11, 2013 Are you planning on keeping compatibility with A8 cartridges? Quote Link to comment Share on other sites More sharing options...
ClausB Posted January 11, 2013 Share Posted January 11, 2013 If we're a bit more clever, we could retain XL compatibility: 1. Reprogram the MMU PAL with both memory maps and wire a mode switch. Replace the '138 with another PAL and 2 wires for the I/O maps. Replace the BASIC ROM with a larger EPROM holding both XL BASIC and the 5200 monitor, using A14 and the new MMU to select. 2. Leave the XL keyboard circuit alone and just remap some of the keys to the 5200 keypad in the monitor ROM. Wire an analog joystick to a 9-pin connector that plugs into the XL port as is. 3. Build the cart adapter to plug into the XL expansion port with 2 more wires for the selects. Build in the mode switch. Quote Link to comment Share on other sites More sharing options...
carmel_andrews Posted January 11, 2013 Share Posted January 11, 2013 Hwo did they make the 5200 access 32k rom space, when the 5200 was basically a 400 minus a keyboard...or did the big A hack some extra rom decoding logic in the 5200 so you could access large rom space Quote Link to comment Share on other sites More sharing options...
ClausB Posted January 11, 2013 Share Posted January 11, 2013 The 74LS139 chip decodes these ranges in the 5200: 0000-3FFF 16K RAM 4000-7FFF 16K ROM 2 8000-BFFF 16K ROM 1 C000-CFFF GTIA E000-EFFF POKEY + external I/O F000-FFFF Monitor ROM See: http://www.atariage....ms-to-the-5200/ Quote Link to comment Share on other sites More sharing options...
31336haxx0r Posted January 13, 2013 Author Share Posted January 13, 2013 That 5200XL combo sounds interesting. Wiring up the 5200 cartridge port doesn't seem to hard. Wasn't the 74xx138 just an 74xx139 with inverse logic? Quote Link to comment Share on other sites More sharing options...
ClausB Posted January 13, 2013 Share Posted January 13, 2013 No, the 139 is a dual 2-to-4 decoder and the 138 is a single 3-to-8. And the address lines going to those decoders differ between the XL and 5200. Quote Link to comment Share on other sites More sharing options...
31336haxx0r Posted January 15, 2013 Author Share Posted January 15, 2013 Maybe some sort of buffer/latch could be utilized to switch between 5200 and XL mode by feeding different stuff to different chips? Quote Link to comment Share on other sites More sharing options...
Rybags Posted January 15, 2013 Share Posted January 15, 2013 Thinking again, maybe the upgrade could be done in concert with a Ram expansion/custom OS scheme. If there was value-added beyond just 5200 games then it'd have a much wider audience. Think Incognito with a few less bells/whistles but 5200 compatability in their place. Quote Link to comment Share on other sites More sharing options...
ClausB Posted January 18, 2013 Share Posted January 18, 2013 Another option would be to not bother with the 5200 cart connector, and program the PALs or CPLD to write-protect the XL RAM above $3FFF in 5200 mode. Then you could boot up in XL mode, load the 5200 monitor and cart programs from disk or other SIO device, switch to 5200 mode, and play the game. 1 Quote Link to comment Share on other sites More sharing options...
31336haxx0r Posted February 1, 2013 Author Share Posted February 1, 2013 That would be awesome! But one still needs to move POKEY's, ANTIC's and other RAM addresses around in the accessible memory area. Maybe that could be done by hardware sniffing a certain, seldomly used address for a distinctive pattern and invoking switchover to 5200 mode and a hard-reset. The 5200 loader would load the game into a specific part of the RAM, write the distinctive code to that address and the hardware would do the rest. A much simpler solution could be a simple switch, though. Quote Link to comment Share on other sites More sharing options...
Innovative Leisure Posted March 9, 2013 Share Posted March 9, 2013 Any updates on the project? Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.