morelenmir Posted August 9, 2018 Share Posted August 9, 2018 (edited) I notice an old post which mentions it is possible to replace the MMU with a 16V8 GAL: MMU Chip Needed I have a couple of LATTICE GAL16V8D15LP chips handy. Would these do the job when programmed with the TL866A? Also, is it just a case of swapping out the MMU and directly plugging in the GAL? I ask because, doing the same with the EMMU seems to be possible as well: https://www.atarimax.com/jindroush.atari.org/achemmu.html However in that case it appears rather more convoluted, requiring the population of an empty header with a 74LS95/74F95 as well as shorting leg 15 of the GAL to ground. For the sake of reference, this is the JEDEC proposed for the MMU: mmupal.jed and this for the EMMU: co25953-gal.jed Edited August 9, 2018 by morelenmir Quote Link to comment Share on other sites More sharing options...
Mathy Posted August 9, 2018 Share Posted August 9, 2018 Hello morelenmir Jindroush found that information here on my Special Stuff Page. After studying the schematics for the gazillionth time years ago, I concluded that U35 was a 74LS95B. This was tested by Guus Assmann and Christopher Lang and confirmed. And I'm under the impression that the information in the JDEC file (which was put together by Chris) for the CO25953 has since been used for quite a few memory expansions. Sincerely Mathy 3 Quote Link to comment Share on other sites More sharing options...
morelenmir Posted August 10, 2018 Author Share Posted August 10, 2018 That sounds pretty straightforward then--the GAL-for-MMU is a direct swap followed by a slightly more complicated GAL+LS95-for-EMMU. I will start out with the MMU first and then try the EMMU. 2 Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted August 10, 2018 Share Posted August 10, 2018 i found that burning an MMU was cost-effective but for the EMMU mod, it is cheaper to just buy a genuine one off ebay UK https://www.ebay.co.uk/itm/NEW-Atari-computer-16-DIP-IC-130XE-65XE-65-130-XE-C25953-20-EMMU-memory-IC-chip/152097265933?hash=item2369b4190d:g:cCoAAOSwCM5XPuiI 3 Quote Link to comment Share on other sites More sharing options...
morelenmir Posted August 11, 2018 Author Share Posted August 11, 2018 i found that burning an MMU was cost-effective but for the EMMU mod, it is cheaper to just buy a genuine one off ebay UK https://www.ebay.co.uk/itm/NEW-Atari-computer-16-DIP-IC-130XE-65XE-65-130-XE-C25953-20-EMMU-memory-IC-chip/152097265933?hash=item2369b4190d:g:cCoAAOSwCM5XPuiI Ah, but then you miss out on all the fun of the chase!!! Seriously though, I can 100% confirm that the MMU JED and swap with a GAL16v8 works completely. I have not done the EMMU yet because I am still waiting for the 74-series logic IC to arrive. 3 Quote Link to comment Share on other sites More sharing options...
1050 Posted August 13, 2018 Share Posted August 13, 2018 Except you haven't fully tested it yet grasshopper... I thought so too, until I started a complex printing project and where I have done it before and knew it like the back of my hand, it would not start with the GAL MMU in place. Suspicious, this might be the issue a swap showed it was the case and the printing began. They do work is the take away, but there can be timing issues even with the best effort to match original and exactly why my GAL failed to function in only this mode is beyond my capabilities to find out about. Just because it doesn't immediately take you to the self test doesn't mean all is perfect. Wish I had a conclusion to this story too but I don't. 1 Quote Link to comment Share on other sites More sharing options...
morelenmir Posted August 13, 2018 Author Share Posted August 13, 2018 Except you haven't fully tested it yet grasshopper... I thought so too, until I started a complex printing project and where I have done it before and knew it like the back of my hand, it would not start with the GAL MMU in place. Suspicious, this might be the issue a swap showed it was the case and the printing began. They do work is the take away, but there can be timing issues even with the best effort to match original and exactly why my GAL failed to function in only this mode is beyond my capabilities to find out about. Just because it doesn't immediately take you to the self test doesn't mean all is perfect. Wish I had a conclusion to this story too but I don't. An excellent point!!! I only have an SIO2SD-USB to attempt printing through, but I will give it a shot. My motivation to swap out the stock MMU was to potentially remove a source of graphical artefacting. Sadly, while--appearing--to work properly the GAL made no difference to the display so I will probably switch back to the original part before long anyway. 1 Quote Link to comment Share on other sites More sharing options...
Barty Posted September 23, 2020 Share Posted September 23, 2020 Hello everyone! In case someone is still looking for C25953 replacement in GAL please check my latest work: https://github.com/mikulski-lab/C25953-emmu/ It fully replicates C25953 so no external latch (74LS95) is required. The drawback is that is not fully 1:1 pin compatible, however if you go with GAL22v10 only a few wire bridges are required on top of the IC so it can be directly inserted into the IC socket on a motherboard. 5 2 Quote Link to comment Share on other sites More sharing options...
blacka013 Posted September 23, 2020 Share Posted September 23, 2020 Great work Barty. Any chance of a photo showing the IC with out the black tape on please? Regards Quote Link to comment Share on other sites More sharing options...
Barty Posted September 23, 2020 Share Posted September 23, 2020 5 hours ago, blacka013 said: Great work Barty. Any chance of a photo showing the IC with out the black tape on please? Regards There you go! 2 Quote Link to comment Share on other sites More sharing options...
soviet Posted December 14, 2020 Share Posted December 14, 2020 On 8/9/2018 at 6:20 PM, morelenmir said: I notice an old post which mentions it is possible to replace the MMU with a 16V8 GAL: MMU Chip Needed I have a couple of LATTICE GAL16V8D15LP chips handy. Would these do the job when programmed with the TL866A? Also, is it just a case of swapping out the MMU and directly plugging in the GAL? I ask because, doing the same with the EMMU seems to be possible as well: https://www.atarimax.com/jindroush.atari.org/achemmu.html However in that case it appears rather more convoluted, requiring the population of an empty header with a 74LS95/74F95 as well as shorting leg 15 of the GAL to ground. For the sake of reference, this is the JEDEC proposed for the MMU: mmupal.jed 3.12 kB · 91 downloads and this for the EMMU: co25953-gal.jed 2.91 kB · 84 downloads Hi, have tried this added a couple of 41464 ram chips, and programmed the GAL16V8B as the link instructed soldered pin 12 to gnd used pin 10 on the gal. The link says to populate U35 using a 74LS95 but on my board this socket is already populated is the 4 memory chips version board. But only got a black screen Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted December 14, 2020 Share Posted December 14, 2020 14 hours ago, soviet said: Hi, have tried this added a couple of 41464 ram chips, and programmed the GAL16V8B as the link instructed soldered pin 12 to gnd used pin 10 on the gal. The link says to populate U35 using a 74LS95 but on my board this socket is already populated is the 4 memory chips version board. But only got a black screen The wiring shown in the above example was for a GAL22v10. For a GAL16V8B, you need to make the PCB adapter as provided in the GitHub site. Quote Link to comment Share on other sites More sharing options...
soviet Posted December 15, 2020 Share Posted December 15, 2020 Now i have done the board, checked everything like 5 times using continuity on the multi meter and also when power on the voltages +5v and gnd seem to be ok. But only got a black screen Quote Link to comment Share on other sites More sharing options...
+mytek Posted December 16, 2020 Share Posted December 16, 2020 I'm not really sure why you are going to so much trouble - making an adapter board. In the 576NUC+ project I use a very inexpensive ATF16V8B-15PU ($0.86 a piece) to replace a stock XEGS MMU - no adapter or jumpering required - just plug it straight into the stock MMU socket. I don't see why this wouldn't also work for a standard XL/XE as well, assuming you use the JED that matches that. I know this chip is programmable with the TL866II Plus, but I suspect it's also possible with the older version of this programmer (look under ATMEL). Don't know about the EMMU though. Is that what the adapter board is for? Edit: I just read back a few posts and apparently that is so if you use this same size chip for the EMMU. For the EMMU in the 576NUC+ I use one these: ATF22V10C-15PU ($1.61 a piece). However my EMMU application is not the same as a 130XE, it's for adding 512K of expanded memory. 3 Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted December 16, 2020 Share Posted December 16, 2020 @soviet does this 65xe work with 64K only without the EMMU parts installed, and before the upgrade attempts too? I see it has micron "mT" stock RAM, which might not be reliable... Could be good to socket the original 2 drams and test the two new ones in their place too... I guess if you had another 130XE you could also test with an original EMMU chip as well to ensure the rest of the system is good... Quote Link to comment Share on other sites More sharing options...
soviet Posted December 16, 2020 Share Posted December 16, 2020 Only have a single 65XE, the computer works using the original 64k of ram, theres something bad about the home made gal-emmu. Will try to purchase an a V10 gal seems easy to get it working. Quote Link to comment Share on other sites More sharing options...
Mathy Posted December 17, 2020 Share Posted December 17, 2020 Hello Michael 22 hours ago, mytek said: However my EMMU application is not the same as a 130XE, it's for adding 512K of expanded memory. Can you tell us what the difference is? Sincerely Mathy Quote Link to comment Share on other sites More sharing options...
+mytek Posted December 17, 2020 Share Posted December 17, 2020 22 hours ago, Mathy said: Can you tell us what the difference is? In the 576NUC+ I'm using a hybrid of @HiassofT and @tf_hh SRAM design. Entirely different than a 130XE's DRAM setup. As for details, some aspects have been covered in the "World's Smallest Atari" topic, and down the road the PLD files for the extended memory circuit will be added to that topic as well. That's about all I can say, because I'm not the architect of that aspect. 1 Quote Link to comment Share on other sites More sharing options...
santosp Posted February 9, 2021 Share Posted February 9, 2021 On 9/23/2020 at 11:40 AM, Barty said: Hello everyone! In case someone is still looking for C25953 replacement in GAL please check my latest work: https://github.com/mikulski-lab/C25953-emmu/ It fully replicates C25953 so no external latch (74LS95) is required. The drawback is that is not fully 1:1 pin compatible, however if you go with GAL22v10 only a few wire bridges are required on top of the IC so it can be directly inserted into the IC socket on a motherboard. I wonder if someone have check if this solution working as a worthy replacement versus the original custom ic from Atari? I mean without side effects in some programs like the one who referred before. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 9, 2021 Share Posted February 9, 2021 (edited) unless something has changed and this one is different, gal emmu also isn't 100%... second PIA mods fail. using the replacements I've tried so far, alond with other fun timing glitches. You can search AA and find some anecdotes and discussion about it. It will be great if this one slays those dragons. Edited February 9, 2021 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
+MrFish Posted February 9, 2021 Share Posted February 9, 2021 26 minutes ago, _The Doctor__ said: fun timing glitches Haha Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 9, 2021 Share Posted February 9, 2021 (edited) Freddy is the cost reduced part, I'd just put the normal Atari memory management back in... the gal thing is as I stated a little bit off (unless something is different with the new offerings...) but so long as we can still choose which way to go on the PCB it really shouldn't matter anyway.. Edited February 9, 2021 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
archeocomp Posted February 9, 2021 Share Posted February 9, 2021 I am lost. What does your last sentence mean? (Pcb..) Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 9, 2021 Share Posted February 9, 2021 printed circuit board? the 130XE replacement printed circuit board... the thing we are all focused on... Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted February 9, 2021 Share Posted February 9, 2021 3 hours ago, santosp said: I wonder if someone have check if this solution working as a worthy replacement versus the original custom ic from Atari? I mean without side effects in some programs like the one who referred before. On the 576NUC+ project from Mytek, we are using programmed GAL chips to function as MMU and EMMU (Extended MMU). They work perfectly for these tasks on that platform. If properly programmed, a GAL replacement for the stock MMU should work well in an XL at least. 3 Quote Link to comment Share on other sites More sharing options...
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