flashjazzcat Posted March 12, 2009 Share Posted March 12, 2009 (edited) Since I eventually want to get the ST up to 1MB, I took it apart for a second time last night and took some (poor) photos of the memory on the motherboard: I was pleased to see an unpopulated bank. I know the STEs are much, much easier, but at least I won't have to desolder a load of RAM chips. I have a few questions: Does the amount of memory installed in the empty bank have to equal the amount in the populated bank? Are suitable memory chips hard to find (I know they'll be reasonably hard to fit) Anything else I need to obtain or consider - apart from resistors, etc? I'm figuring this must be a reasonably common upgrade on this particular motherboard revision so I'd love to hear from anyone who's actually upgraded to 1MB in this way. Are there instructions anywhere? Edited March 12, 2009 by flashjazzcat Quote Link to comment Share on other sites More sharing options...
Chandler Posted March 12, 2009 Share Posted March 12, 2009 yes you must populate the upper bank in the same way as the lower bank ie: solder in another 16 chips the same! it will work without the small yellow resistors but probably advisable to use them you will also need 3 x 68R resistors to turn the bank on (they are located just as your picture ends, you will see 3 resistors missing at the end of a bank of them just abouve the MMU chip (square black chip) you need good soldering skills and a magnifying glass on a mount to see what you are doing properly they are quite hard to find i have found those chips or i have seen them at silly prices your other option would be a Marpet upgrade kit or similar which plugs into the MMU and SHIFTER chips, using that you could go all the way up to 4mb, no soldering required again it's finding that kit... Quote Link to comment Share on other sites More sharing options...
mellis Posted March 12, 2009 Share Posted March 12, 2009 I too have a 520STfm to upgrade, but instead of going to 1MB (which is still not enough RAM for the software I think you're going to want to run -- I had a 1040ST (1MB RAM) that I needed to upgrade back in the day) I'm shooting for 4MB. I found this document describing installing a 72-pin SIMM to be compelling. This procedure is a fair amount of work, but soldering in 16 more ICs is a fair amount of work too. I figure while I'm soldering, I might as well take it all the way up to 4MB. 72-pin SIMM upgrade Also, the traces on the ST motherboards are extremely fragile. If you were to populate those RAM banks, I would install sockets first. Of course, if you go with the 72-pin simm upgrade, you can skip installing the sockets. One thing to mention: I plan to use a rotary cutter to remove ALL of the RAM from my ST's mainboard. Once the chips are gone, I will desolder each stub one-by-one. At that point, the board will be ready for the upgrade. Of course, Best Electronics does sell SIMM upgrade kits, but they cost more than a second-hand STe would. For that reason, I think I'm going to go for it! Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted March 12, 2009 Author Share Posted March 12, 2009 (edited) I found this document describing installing a 72-pin SIMM to be compelling. This procedure is a fair amount of work, but soldering in 16 more ICs is a fair amount of work too. I figure while I'm soldering, I might as well take it all the way up to 4MB. 72-pin SIMM upgrade Thanks; I've bookmarked it to read in detail later. The cost of many third-party upgrade kits is unjustifiable for a machine I bought for 10 GBP. I have a habit of buying things off the shelf when it might be more challenging (and cost effective) to make them myself. I can see the point about going to 4MB, too. It all looks like pretty hair-raising stuff, though! Edited March 12, 2009 by flashjazzcat Quote Link to comment Share on other sites More sharing options...
Sub(Function(:)) Posted March 12, 2009 Share Posted March 12, 2009 yes you must populate the upper bank in the same way as the lower bank ie: solder in another 16 chips the same! it will work without the small yellow resistors but probably advisable to use them Actually they are capacitors (in this case called "decoupling capacitors") I cannot read the ones placed on the boards to tell you what size to use, but if you cannot source the same type you should probably go for ceramic disc capacitors of the same size or very close equivalent. These are not critical component, but they are fitted as a "good design" practice. They are fitted, one close to each IC between a supply pin and its ground pin. Not fitting them MAY cause problems. Quote Link to comment Share on other sites More sharing options...
Fuji-Man Posted March 12, 2009 Share Posted March 12, 2009 Decoupling caps are usually .1 µf (microfarad). Note decimal point. yes you must populate the upper bank in the same way as the lower bank ie: solder in another 16 chips the same! it will work without the small yellow resistors but probably advisable to use them Actually they are capacitors (in this case called "decoupling capacitors") Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted March 13, 2009 Author Share Posted March 13, 2009 What kind of RAM chips are already fitted to the motherboard in the picture? I've tried searching on various permutations of the serial numbers, etc, but with little success. I assume it's going to take a lucky day on ebay or a specialist on-line vintage chip vendor to find these things... Quote Link to comment Share on other sites More sharing options...
puppetmark Posted March 14, 2009 Share Posted March 14, 2009 What kind of RAM chips are already fitted to the motherboard in the picture? I've tried searching on various permutations of the serial numbers, etc, but with little success. I assume it's going to take a lucky day on ebay or a specialist on-line vintage chip vendor to find these things... They are Dynamic RAM chips, D41256. Here is the datasheet: These should not be too hard to find. Look at surplus PC places. These chips were used in old video cards. also, there seems to be lots of them on ebay: http://cgi.ebay.co.uk/DRAM-NEC-D41256C-12-...p3286.m63.l1177 D41256.pdf Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted March 14, 2009 Author Share Posted March 14, 2009 They are Dynamic RAM chips, D41256. Here is the datasheet: These should not be too hard to find. Look at surplus PC places. These chips were used in old video cards. also, there seems to be lots of them on ebay: http://cgi.ebay.co.uk/DRAM-NEC-D41256C-12-...p3286.m63.l1177 D41256.pdf That's great, thanks. I might snag 16 of those. I've sourced the decoupling capacitors, too. I'm still unclear exactly where the 3 x 68R resistors go, though... Total cost for this 1MB upgrade (hopefully not including a ruined motherboard) will be around 25GBP. I can't justify $90 for the marpet at the moment: perhaps this is something I could look at if 1MB proves restrictive in the future. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted March 15, 2009 Author Share Posted March 15, 2009 I want to socket the chips. Are these the correct sockets? http://cgi.ebay.co.uk/20-pcs-16-pin-DIP-IC...A1%7C240%3A1318 Quote Link to comment Share on other sites More sharing options...
mimo Posted March 15, 2009 Share Posted March 15, 2009 I want to socket the chips. Are these the correct sockets? http://cgi.ebay.co.uk/20-pcs-16-pin-DIP-IC...A1%7C240%3A1318 yes Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted March 15, 2009 Author Share Posted March 15, 2009 I want to socket the chips. Are these the correct sockets? http://cgi.ebay.co.uk/20-pcs-16-pin-DIP-IC...A1%7C240%3A1318 yes Thanks! I'll order everything and then do the job when my soldering skills are sufficiently honed... Quote Link to comment Share on other sites More sharing options...
mellis Posted March 15, 2009 Share Posted March 15, 2009 Speaking of soldering, I am considering updating my setup. I've been using a non-variable 15W iron for about 20 years, and although it has served me well, I am ready to upgrade. Also, upgrading old computers often presents desoldering opportunities. I have had some success with desoldering braid, but I'd love any suggestions about soldering stations and related desoldering tools. I've had no success with a desoldering bulb. Does anybody have a favorite tool for either/both of these jobs? What do you feel is the best value? Thanks! Quote Link to comment Share on other sites More sharing options...
techie_alison Posted March 15, 2009 Share Posted March 15, 2009 I use these; For soldering; Weller WSP80 For desoldering; Iron with a pump built in And for SMD / hot air work; The iron is going to be expensive! The desoldering iron is cheap and nasty. The SMD work station, ...well they're a blatant rip off. I paid £60 for mine. As for desoldering, just get a manual pump. For the more advanced stuff you just can't do it with a wick, I don't like them! Wicks are for old farts. There are also tricks, like rather than trying to get the solder off... Just keep on putting more and more on, and then flick the whole lot off. Also, flux goes a long way too. Quote Link to comment Share on other sites More sharing options...
mellis Posted March 16, 2009 Share Posted March 16, 2009 Thanks, Alison. I'm intrigued by the desoldering iron (the vacuum pump one). Do you have a manufacturer/model number for that one? Quote Link to comment Share on other sites More sharing options...
techie_alison Posted March 16, 2009 Share Posted March 16, 2009 It's just some generic rubbish one made in China. There's no regulation on it, and it gets bloody hot!! Will easily take up tracks too. I use it to tidy up mainly. The holes in the photo up above were cleaned up with it. You just won't achieve that with anything else, certainly not on 25-year old lead solder. Today's solder is harder to work, but it's alot cleaner. http://www.rapidonline.com/Tools-Fasteners.../kw/desoldering Quote Link to comment Share on other sites More sharing options...
+poobah Posted March 16, 2009 Share Posted March 16, 2009 /me lusting after the nice Weller setup Quote Link to comment Share on other sites More sharing options...
techie_alison Posted March 17, 2009 Share Posted March 17, 2009 (edited) /me lusting after the nice Weller setup Oh go on. You owe it to yourself!! Just go and buy the bloody thing!! Get the WSP80 though. That's just my preference though, as I don't like the WMP80. BUY BUY BUY! http://www.flickr.com/photos/old_computers/ Edited March 17, 2009 by techie_alison Quote Link to comment Share on other sites More sharing options...
techie_alison Posted March 17, 2009 Share Posted March 17, 2009 So then Poobah, have you treated yourself yet? :) Quote Link to comment Share on other sites More sharing options...
+poobah Posted March 17, 2009 Share Posted March 17, 2009 So then Poobah, have you treated yourself yet? :) Argh... the international peer pressure.... how long can I stand it! Quote Link to comment Share on other sites More sharing options...
techie_alison Posted March 18, 2009 Share Posted March 18, 2009 (edited) Well look at it from this point of view... So often we just go out and waste money and buy rubbish which we're not really happy with. That iron I've been happy with over and over again. It's been £200 very well spent. They're also a bit cheaper for you guys over there too. Up until a couple of years ago I used to use the cheap Antex irons (about £20/$30) and yes I did pretty much ok with them. But this one, there's just no comparison. The tips are pretty cheap too, where as the bits on the cheaper irons eventually oxidise and fall to bits. BUY BUY BUY!! Edited March 18, 2009 by techie_alison Quote Link to comment Share on other sites More sharing options...
+poobah Posted March 18, 2009 Share Posted March 18, 2009 Well look at it from this point of view... So often we just go out and waste money and buy rubbish which we're not really happy with. That iron I've been happy with over and over again. It's been £200 very well spent. They're also a bit cheaper for you guys over there too. Up until a couple of years ago I used to use the cheap Antex irons (about £20/$30) and yes I did pretty much ok with them. But this one, there's just no comparison. The tips are pretty cheap too, where as the bits on the cheaper irons eventually oxidise and fall to bits. BUY BUY BUY!! wd1/wp80 setup on ebay I have a Solomon SL-30 right now, but its kinda finicky. Quote Link to comment Share on other sites More sharing options...
techie_alison Posted March 18, 2009 Share Posted March 18, 2009 (edited) I have a Solomon SL-30 right now, but its kinda finicky. Looks like soldering with a plumbing soldering iron. Get yourself a Weller. Don't buy off eBay, find a local supplier and go and pick it up personally. WSP80 (the one with the removable barrel). I think you should pack some sandwiches, and take a flask of tea. Make it a morning out. Edited March 18, 2009 by techie_alison Quote Link to comment Share on other sites More sharing options...
+poobah Posted March 18, 2009 Share Posted March 18, 2009 I have a Solomon SL-30 right now, but its kinda finicky. Looks like soldering with a plumbing soldering iron. Get yourself a Weller. Don't buy off eBay, find a local supplier and go and pick it up personally. WSP80 (the one with the removable barrel). I think you should pack some sandwiches, and take a flask of tea. Make it a morning out. Amazingly enough, I've been able to solder quite a few SOIC chips with it. Local supplier: Say "Beavercreek" out loud in your best mid-western US drawl, it might be quite a trip. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted March 23, 2009 Author Share Posted March 23, 2009 DRAM and sockets arrived today, all for 25 GBP. The ST is in pieces ATM, part way through the "Retr0Brite" treatment (waiting for sun), but I'm going to do the Peterson upgrade on the XE as a warm up before I do the ST's 1MB upgrade. The XE's extra bank is already socketed; would that this were the case with the ST. I remember the 8-bit sockets were fitted by quite a seasoned solderer but it was still a fiddly job. Quote Link to comment Share on other sites More sharing options...
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