flashjazzcat Posted February 14, 2010 Share Posted February 14, 2010 (edited) Pleased to find this thread: I've just bought an XEGS and I'm interested in upgrading the RAM. Not sure whether I'll go for 128K or something bigger. A 1MB SIMM upgrade would be nice. I notice Satantronic's mod uses a special EXTMMU, however. On the other hand, it might be cheaper than a CO25953. Any recommendations on how to proceed? Edited February 14, 2010 by flashjazzcat Quote Link to comment Share on other sites More sharing options...
Mathy Posted February 14, 2010 Share Posted February 14, 2010 Hello Jon The EXTMMU is nothing more then a PAL or something like that. But you can also replace the CO25953 with this. Or buy a CO25953 at Best or B&C for $10 or $12.50. greetings Mathy Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted February 15, 2010 Share Posted February 15, 2010 With the prices of PAL chips what they are (at least everywhere I've looked), the CO25953 doesn't seem so expensive. I suppose I need a GAL programmer: it would be useful in many circumstances. Best are all out of the XEGS upgrade kits anyway. I assume I could build this easily enough with a few resistors, a CO25953 and a couple of suitable DRAMs: Quote Link to comment Share on other sites More sharing options...
Mathy Posted February 15, 2010 Share Posted February 15, 2010 Hello Jon Next to "U13" it says "only pins" and "connected between", but I can't make out what behind "pins". Can you tell me? greetings Mathy Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted February 15, 2010 Share Posted February 15, 2010 Next to "U13" it says "only pins" and "connected between", but I can't make out what behind "pins". Can you tell me? greetings Mathy The scan is unclear there because the toner is coming off in flakes near the folds on my original copy. I don't have the original handy, but it probably says pins 8 and 16 (at least that's what it's supposed to say). It's basically telling you that the CO25953 should be mounted on top of U13--a 74LS138, I believe--with only pins 8 and 16 connected for ground and +5V, respectively. This is also documented in the installation instructions, in step 7. And yes, aside for the CO25953, there's nothing special about any of the parts in that upgrade kit; you can use your own resistors and 64Kx4 DRAM chips. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted February 15, 2010 Share Posted February 15, 2010 (edited) Hello Jon Next to "U13" it says "only pins" and "connected between", but I can't make out what behind "pins". Can you tell me? Hmmm, yeah. That's pretty cruicial info missing there. From experience only, I'd say it should be 8 and 16, since that's the way the 74LS158 sits on top of the buffer chip U24 in the 320K upgrade for the XE. It took me a while to realize that all it's after is a power supply, so one pin will be +5v and the other ground. So I take it the custom chip in this case is the aforementioned CO25953? I should have some suitable DRAMs lying around, so with a custom IC I could get cracking with this mod. EDIT: Ha... beat me to it! Best have a minimum Google Checkout order of $30 (IIRC), so I'm just trying to think of anything else I need. I'm always open to doing joint orders with people in the UK in order to cut down on postage, etc. The only trouble is the lengthy wait. It could take a while for that CO25953 to arrive! Edited February 15, 2010 by flashjazzcat Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted February 15, 2010 Share Posted February 15, 2010 I just remembered that I promised to post a picture of my completed mod, so here it is: I used yellow heat shrink tubing to cover the resistors and the bent-up pins on the chips. Here are the PIA resistors on the underside of the board (installed in step 9 of the instructions): 1 Quote Link to comment Share on other sites More sharing options...
puppetmark Posted February 15, 2010 Share Posted February 15, 2010 Next to "U13" it says "only pins" and "connected between", but I can't make out what behind "pins". Can you tell me? greetings Mathy The scan is unclear there because the toner is coming off in flakes near the folds on my original copy. I don't have the original handy, but it probably says pins 8 and 16 (at least that's what it's supposed to say). It's basically telling you that the CO25953 should be mounted on top of U13--a 74LS138, I believe--with only pins 8 and 16 connected for ground and +5V, respectively. This is also documented in the installation instructions, in step 7. And yes, aside for the CO25953, there's nothing special about any of the parts in that upgrade kit; you can use your own resistors and 64Kx4 DRAM chips. yep, 8 and 16 are the power and ground connections. I took a CO25953 out of a dead 130XE and I did this mod last week while being snowed in. It works great and It only took about 2 and a half hours to complete. I used heat shrink tubing to insulate where I had to solder to resisters ( I highly recomned it) and I used a 4 x 3.3k resistor network for the pull-ups on the PIA. I think its easier to solder as it already has a common connection and spaced the same as the PIA pins. I will try and post a picture when I can. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted February 15, 2010 Share Posted February 15, 2010 That's neat job. Hopefully I'll be having a go at this myself tomorrow if the XEGS arrives. I have a 130XE with a socketed CO25953 which I could use for "testing", but I'll need a replacement chip sooner or later. Quote Link to comment Share on other sites More sharing options...
Mathy Posted February 15, 2010 Share Posted February 15, 2010 Hello Jon Best have a minimum Google Checkout order of $30 (IIRC), so I'm just trying to think of anything else I need. More CO25953's? greetings Mathy Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted February 16, 2010 Share Posted February 16, 2010 LOL! Best have sold out of the XEGS upgrade kits, by the way. I have about 20 OKI M3764-15RS DRAMs pulled from an old ISA graphics card. I thought they were suitable for this upgrade, but looks like they're 64k x 1 chips. Looks like I'll have to look for DRAMs too. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted February 17, 2010 Share Posted February 17, 2010 Well, I've ordered a CO25953, 2 x 64k x 4 DRAMs, a spare MMU (I have a habit of destroying these), and a spare 130XE badge from Best. The XEGS arrived this morning and I must say I LOVE it. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted February 26, 2010 Share Posted February 26, 2010 Just finished doing this 128K mod and I was delighted to find it worked first time. Best were out of ready-made XEGS kits so I just ordered equivalent parts. The information and photos in this thread were most helpful. Thanks everyone. Quote Link to comment Share on other sites More sharing options...
tregare Posted February 26, 2010 Share Posted February 26, 2010 Just finished doing this 128K mod and I was delighted to find it worked first time. Best were out of ready-made XEGS kits so I just ordered equivalent parts. The information and photos in this thread were most helpful. Thanks everyone. does anyone have the flash file for the MMU? ISTR it is just a PAL, and should be able to be replaced with a GAL or PEEL. Quote Link to comment Share on other sites More sharing options...
tregare Posted February 26, 2010 Share Posted February 26, 2010 Hello Jon The EXTMMU is nothing more then a PAL or something like that. But you can also replace the CO25953 with this. Or buy a CO25953 at Best or B&C for $10 or $12.50. greetings Mathy nevermind my last request went here and now have the vhdl and jedec to burn a Gal/Peel. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted February 27, 2010 Share Posted February 27, 2010 nevermind my last request went here and now have the vhdl and jedec to burn a Gal/Peel. What kind of equipment are you using to burn the chip? Did you build your own flasher? Quote Link to comment Share on other sites More sharing options...
tregare Posted February 28, 2010 Share Posted February 28, 2010 nevermind my last request went here and now have the vhdl and jedec to burn a Gal/Peel. What kind of equipment are you using to burn the chip? Did you build your own flasher? supposedly the Willem PRO programmer I have will write GAL, PEEL and PAL chips, and I believe my old pocket programmer from xtronics will do so too. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted February 28, 2010 Share Posted February 28, 2010 supposedly the Willem PRO programmer I have will write GAL, PEEL and PAL chips, and I believe my old pocket programmer from xtronics will do so too. Something like this? I've wanted one for a while, but they've seemed too expensive. This one's almost affordable for me at the moment. Quote Link to comment Share on other sites More sharing options...
mimo Posted February 28, 2010 Share Posted February 28, 2010 Good luck with any willans programmer, nothing but trouble IMO Quote Link to comment Share on other sites More sharing options...
+bf2k+ Posted February 28, 2010 Share Posted February 28, 2010 I have never had any trouble with my Willem (other than a virus on the software CD)... but I have only burned EEPROMS with it. Quote Link to comment Share on other sites More sharing options...
+Mitch Posted February 28, 2010 Share Posted February 28, 2010 Good luck with any willans programmer, nothing but trouble IMO Yeah, I've heard a lot of people complain about Willem programmers. They don't have a very good reputation. Mitch Quote Link to comment Share on other sites More sharing options...
atariksi Posted February 28, 2010 Share Posted February 28, 2010 Good luck with any willans programmer, nothing but trouble IMO Yeah, I've heard a lot of people complain about Willem programmers. They don't have a very good reputation. Mitch The only trouble I had with them was installing their software under Win 2000/XP as the driver for direct I/O port wasn't installing properly. But once installed, it worked fine. One other issue was writing to devices that required exact timing since the power management amongst other things interferes with the timing. But that's not their fault that there's no standard way of disabling power management. Quote Link to comment Share on other sites More sharing options...
tregare Posted March 1, 2010 Share Posted March 1, 2010 supposedly the Willem PRO programmer I have will write GAL, PEEL and PAL chips, and I believe my old pocket programmer from xtronics will do so too. Something like this? I've wanted one for a while, but they've seemed too expensive. This one's almost affordable for me at the moment. looking at the page for the model I have (willem pro 5.5 PCB) they no longer list gal/pal as supported devices Quote Link to comment Share on other sites More sharing options...
mimo Posted March 1, 2010 Share Posted March 1, 2010 The only problem I had was burning any ROMs with it:( Even with an external power supply it would not burn a usable image. Messing with all the dip switches using different eproms, different images, different PC's etc never gave a usable result. I know that there are some mods that can be done that are supposed to make the thing work, but I gave up and gave it to someone on AtariAge. Don't think they got it working either. Quote Link to comment Share on other sites More sharing options...
atariksi Posted March 1, 2010 Share Posted March 1, 2010 The only problem I had was burning any ROMs with it:( Even with an external power supply it would not burn a usable image. Messing with all the dip switches using different eproms, different images, different PC's etc never gave a usable result. I know that there are some mods that can be done that are supposed to make the thing work, but I gave up and gave it to someone on AtariAge. Don't think they got it working either. The USB power works fine if you boot up the computer with the USB cable attached. If you plug in the USB cable after the computer is on, it doesn't seem to power up properly at least on my machine. The computer doesn't detect any device on the USB cable since it's only used for power and the parallel port is used for all the I/O. I have burned EEPROMs, EPROMs, SRAMS, and FLASH chips w/o any problems. It should be possible to hack the Willem programmer to an A8 through the joysticks ports. Quote Link to comment Share on other sites More sharing options...
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