Mercenary6502 Posted October 2, 2015 Author Share Posted October 2, 2015 One tip for 4464 chips is to look for old ISA graphics cards as these were often used on them Good tip! I thought the same and was actually going through my stash of ISA stuff before considering the SRAM but came out empty handed. I kind of hate to rob chips from some of those anyway. Quote Link to comment Share on other sites More sharing options...
Ralphy Rocket Posted October 2, 2015 Share Posted October 2, 2015 Hi. Working from memory here... /cas is selecting 64k in a 600xl that's why the upgrade is so easy with 64kX4 chips. All signals are there (except 2 I think) . Forgive me for this dumb question....are A14 and A15 connected to your SRAM? and thanks for this topic, I'm about to do the same to my 1200xl and my barrier is decoding/selecting. How about a picture? :-) Sent from my 7040N using Tapatalk Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 2, 2015 Author Share Posted October 2, 2015 OK so I compared the 64K DRAM mod to the Schema; 1. It's appling A14 and A15 to the '158s. You wouldn't need to do this 'cause no DRAMS 2. The OR gate Pin 9 is hardwired to GND. This gate controls when CAS is passed to the DRAMs, by default this is only when A14 and A15 are low. So it seems to me, if the SRAM is working with the default CAS driving /CS, by doing the change to U18.9 you should see the same amount of RAM as the 64K DRAM mod would. I think the MMU will lower the total amount when mapping in I/O and ROMs. Maybe? Yogi First off, thanks a ton for your help Yogi!! I reviewed the 64k DRAM upgrade awhile back in the same link you sent and I remembered the logic changes that were done last night. So I went and reviewed it recently just as you did. I too made the same observation about tying pin 9 of U18 to ground. I also found that you can pull the chip out and jump lines 10 and 8 together to accomplish the same task, or you can connect the SRAM's CS line directly to pin 8 of U16. So there's three chip select options for ya! Now I'm not gonna lie and you guys are going to hate me for this, but I've been using a 62256 (32kx8) chip because it's what I had on hand and I'm a cheap a** lol. So once I get a 64k or larger chip it should work just fine. In case any of you are curious, if using either one of those three chip select options with my 32k RAM, the will Atari boot up automatically to the memory test screen and will recognize all 32k of the ram before maxing out and crashing since there's no logic to limit the address range. Therefore, like I said, once I get a bigger RAM it should (hopefully) work just fine. Well, I'll keep you all posted. It might take a week or so to get the bigger ram, but I won't stop until I can get Donkey Kong playing! If all goes well, I might even make a diagram/schematic and put it on here to help others trying to accomplish the same task as me. After all, those old DRAM's are pretty obsolete! Thank you all for the help! Quote Link to comment Share on other sites More sharing options...
Ralphy Rocket Posted October 2, 2015 Share Posted October 2, 2015 Awesome! :-) But you did say you only saw 16k? Not 32k of your 32k chip? Sent from my 7040N using Tapatalk Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 2, 2015 Author Share Posted October 2, 2015 Hi. Working from memory here... /cas is selecting 64k in a 600xl that's why the upgrade is so easy with 64kX4 chips. All signals are there (except 2 I think) . Forgive me for this dumb question....are A14 and A15 connected to your SRAM? and thanks for this topic, I'm about to do the same to my 1200xl and my barrier is decoding/selecting. How about a picture? :-) Sent from my 7040N using Tapatalk Yes, those address lines are used (at least A14 for now since I'm using a 32k chip) And not a dumb question because simple things like that can be easily overlooked! It's quite messy right now from experimenting, but here's a pic! As you can see, I was able to solder the RAM on top of my Basic Rom adapter: Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 2, 2015 Author Share Posted October 2, 2015 (edited) Awesome! :-) But you did say you only saw 16k? Not 32k of your 32k chip? Sent from my 7040N using Tapatalk Originally, yes. But then after modifying the DRAM's old CAS line it will now see the full 32k. But just up until the morning I didn't know how to do that (Edit: and the reason for only seeing 16k was because the non-modified CAS line disables past 16k since it had only 16k of ram before) Edited October 2, 2015 by programmer6502 Quote Link to comment Share on other sites More sharing options...
Van Posted October 2, 2015 Share Posted October 2, 2015 First off, thanks a ton for your help Yogi!! I reviewed the 64k DRAM upgrade awhile back in the same link you sent and I remembered the logic changes that were done last night. So I went and reviewed it recently just as you did. I too made the same observation about tying pin 9 of U18 to ground. I also found that you can pull the chip out and jump lines 10 and 8 together to accomplish the same task, or you can connect the SRAM's CS line directly to pin 8 of U16. So there's three chip select options for ya! Now I'm not gonna lie and you guys are going to hate me for this, but I've been using a 62256 (32kx8) chip because it's what I had on hand and I'm a cheap a** lol. So once I get a 64k or larger chip it should work just fine. In case any of you are curious, if using either one of those three chip select options with my 32k RAM, the will Atari boot up automatically to the memory test screen and will recognize all 32k of the ram before maxing out and crashing since there's no logic to limit the address range. Therefore, like I said, once I get a bigger RAM it should (hopefully) work just fine. Well, I'll keep you all posted. It might take a week or so to get the bigger ram, but I won't stop until I can get Donkey Kong playing! If all goes well, I might even make a diagram/schematic and put it on here to help others trying to accomplish the same task as me. After all, those old DRAM's are pretty obsolete! Thank you all for the help! Very COOL!! Will definitely want to hear how you make out with a larger SRAM. Yogi 1 Quote Link to comment Share on other sites More sharing options...
Ralphy Rocket Posted October 2, 2015 Share Posted October 2, 2015 NICE! a thing of beauty really! Thanks for the inspiration! :-) I like taking signals of the vias too! Sent from my 7040N using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 8, 2015 Author Share Posted October 8, 2015 Well, got that bigger chip in the mail today: So I quickly went to work and.... Success! And the best part is, I can now play Donkey Kong! So there you go, a cheap and stubborn man's Atari 600XL 64K modern SRAM upgrade! (Which probably actually costs you more than getting a readily avaiable RAM upgrade board... ) I'll try and make some diagrams and get a final pic of the inside once I clean everything up for those interested. And just for kicks, here's all the chips I was able to do away with below! Once again, thanks for all the help and support to all of you who contributed to this thread! 1 Quote Link to comment Share on other sites More sharing options...
Van Posted October 8, 2015 Share Posted October 8, 2015 Very cool! Must have DK At some point will be doing a upgrade on a flaky 600XL (think its DRAMs are going. Last time I had it on, after an hour or so, was corrupting characters on the screen.). For me, SRAMs are the way to go, have a few in the 'parts bin' So cost wise it's a no brainer. Yogi Quote Link to comment Share on other sites More sharing options...
ClausB Posted October 9, 2015 Share Posted October 9, 2015 Congrats! What logic gates did you use on your perf board? Would you like a small mod to allow 128K access similar to the 130XE? Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 9, 2015 Author Share Posted October 9, 2015 (edited) Congrats! What logic gates did you use on your perf board? Would you like a small mod to allow 128K access similar to the 130XE? Actually yes I would now that I'm to that point, I mean why not? The logic I have is a 74LS00N used to combine the Atari's R/W and PH2 clock as the SRAM's R/W enable. The other chip is an 74LS08N that isn't being used. It's there because I was trying to temporarily make a 32K address divider (along with one unused inverter that I found on the 600XL board) so I could use all of that old 32K SRAM I had without it crashing while I waited for the bigger chip. For some reason though, it had unwanted behavior no matter what I tried! But... It's not important now Thanks Edited October 9, 2015 by programmer6502 Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 9, 2015 Author Share Posted October 9, 2015 (edited) For those of you wanting to the 64K mod, I drew this up last night. I hope it proves useful to some you: I think I corrected most of the mistakes (if any). And as usual, I'm not responsible for any damages done when attempting this mod, so please proceed at your own risk!! The best tip I can provide is double check that VCC and GND aren't directly shorted with a multimeter before powering on. As for other shorts/misconnections, TTL based stuff is pretty forgiving. But seriously, do be careful and double (even triple) check your work! Edited October 9, 2015 by programmer6502 Quote Link to comment Share on other sites More sharing options...
ClausB Posted October 10, 2015 Share Posted October 10, 2015 Do you need the NAND gates? Doesn't the DRAMs' /WE signal already have the right timing? Did you try that? BTW the 128K mod I have in mind will use those 2 LS158s you pulled, so don't toss them. Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 10, 2015 Author Share Posted October 10, 2015 Do you need the NAND gates? Doesn't the DRAMs' /WE signal already have the right timing? Did you try that? BTW the 128K mod I have in mind will use those 2 LS158s you pulled, so don't toss them. That's good question about the singnal, I'll try using the old WE and report back. Yeah I wouldn't toss those chips, go ahead and tell me what needs to be done. I'm all in for 128K! Thanks Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 10, 2015 Author Share Posted October 10, 2015 Just tried it and totally forgot that I had already tired it before. Using the DRAM's old WE signal causes the computer to malfunction like crazy. So unfortunately, that extra logic is necessary. Good thinking though. Quote Link to comment Share on other sites More sharing options...
Ralphy Rocket Posted October 10, 2015 Share Posted October 10, 2015 EXCELLENT! your next project is extending the memory....:-) Sent from my 7040N using Tapatalk Quote Link to comment Share on other sites More sharing options...
ClausB Posted October 10, 2015 Share Posted October 10, 2015 Try this: Bend up pins 1, 2, 3, 4, and 15 of an LS158 and plug it into socket U5. Bend up all pins of the other LS158 except 8 and 12 thru 16 and plug it into socket U6. Then connect the bent up pins as follows: U5-1 to A15 U5-2 to A14 U5-3 to Gnd U5-4 to U6-1 U5-15 to PB4 U6-2 to PB3 U6-3 to A14 U6-4 to SRAM A14 U6-5 to PB2 U6-6 to A15 U6-7 to SRAM A15 U6-9 to SRAM A16 U6-10 to Gnd U6-11 to +5V Good luck. Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 11, 2015 Author Share Posted October 11, 2015 Try this: Bend up pins 1, 2, 3, 4, and 15 of an LS158 and plug it into socket U5. Bend up all pins of the other LS158 except 8 and 12 thru 16 and plug it into socket U6. Then connect the bent up pins as follows: U5-1 to A15 U5-2 to A14 U5-3 to Gnd U5-4 to U6-1 U5-15 to PB4 U6-2 to PB3 U6-3 to A14 U6-4 to SRAM A14 U6-5 to PB2 U6-6 to A15 U6-7 to SRAM A15 U6-9 to SRAM A16 U6-10 to Gnd U6-11 to +5V Good luck. Followed your directions and powered it on and it booted right up the first time! As far as extra RAM goes, the FRE function in Atari Basic reports the same amount of RAM as before, but I assume it probably doesn't know how to see the extra 64K bank. So I then went on a hunt for 130XE specific software/games and it seems to load everything just fine! Even tried a ramdisk and that seems to work too. I'm unfamiliar with ramdisks and other 130XE stuff but it seems like it has 128K now! Is there a memory test program of some sort that could 100% verify? (Still need to clean up in there ) Quote Link to comment Share on other sites More sharing options...
Joey Z Posted October 11, 2015 Share Posted October 11, 2015 Followed your directions and powered it on and it booted right up the first time! As far as extra RAM goes, the FRE function in Atari Basic reports the same amount of RAM as before, but I assume it probably doesn't know how to see the extra 64K bank. So I then went on a hunt for 130XE specific software/games and it seems to load everything just fine! Even tried a ramdisk and that seems to work too. I'm unfamiliar with ramdisks and other 130XE stuff but it seems like it has 128K now! Is there a memory test program of some sort that could 100% verify? (Still need to clean up in there ) XRAM, is one program that should be able to test your extended RAM. Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 11, 2015 Author Share Posted October 11, 2015 XRAM, is one program that should be able to test your extended RAM. Thanks! Gave it a try, but it only reports 4 banks totaling to 64K (maybe I'm not using it correctly). It's gotta be working though because when booting DOS 2.5, it says "setting up Atari 130XE ramdisk". It didn't say that before. The original plan was to load this 600XL up for someone else but it's becoming so fancy I might have to keep it! Maybe I'll bring my trusty 800XL up to speed. I've also thought about designing a new edition of my Basic ROM adapter that will include the 64K SRAM upgrade on the same board, making it easy to upgrade other 600XL's and possibly 800XL's with dying DRAM. (If any of you are interested). Anyway, thanks ClausB for the 128K RAM suggestion and instructions! I hope this thread has and will be useful for others with the same idea now that I've successfully upgraded from 16K. I enjoyed the challenge Quote Link to comment Share on other sites More sharing options...
Joey Z Posted October 11, 2015 Share Posted October 11, 2015 Thanks! Gave it a try, but it only reports 4 banks totaling to 64K (maybe I'm not using it correctly). It's gotta be working though because when booting DOS 2.5, it says "setting up Atari 130XE ramdisk". It didn't say that before. The original plan was to load this 600XL up for someone else but it's becoming so fancy I might have to keep it! Maybe I'll bring my trusty 800XL up to speed. I've also thought about designing a new edition of my Basic ROM adapter that will include the 64K SRAM upgrade on the same board, making it easy to upgrade other 600XL's and possibly 800XL's with dying DRAM. (If any of you are interested). Anyway, thanks ClausB for the 128K RAM suggestion and instructions! I hope this thread has and will be useful for others with the same idea now that I've successfully upgraded from 16K. I enjoyed the challenge no that's right, xram is reporting the size of your extended RAM which is 64KB on top of the 64KB base RAM. Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 11, 2015 Author Share Posted October 11, 2015 no that's right, xram is reporting the size of your extended RAM which is 64KB on top of the 64KB base RAM. Oh, gotcha. It's a neat little program. Quote Link to comment Share on other sites More sharing options...
ClausB Posted October 11, 2015 Share Posted October 11, 2015 Great! Glad it works. I made a small mistake: Pin 10 of socket U6 is already Gnd, so there is no need to bend pin 10 up and wire it to Gnd. Quote Link to comment Share on other sites More sharing options...
Mercenary6502 Posted October 11, 2015 Author Share Posted October 11, 2015 Great! Glad it works. I made a small mistake: Pin 10 of socket U6 is already Gnd, so there is no need to bend pin 10 up and wire it to Gnd. That's cool, it's an easy fix. Those instructions you wrote were great how you had all the pins and their connections in order from least to greatest, made it a breeze to go through! BTW, I like your profile pic. Was that a demo or something that ran on the Atari? Quote Link to comment Share on other sites More sharing options...
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