How hard would it be to get a 520ST to 1MB RAM?

[AB Positive]

So I got lucky and won a stock 520ST from Cebus' raffle. Being the amateur hacker that I am, I'd love to mod the puppy up when I get it.

 

Question is - how hard would a RAM upgrade be? I've seen the SIMM mods floating about, but that might be a bit much even for me who does have (some) soldering experience.

 

I've heard of doing piggybacks or DRAM replacing... I did a similar thing to make a 64K 600XL and that idea doesn't bother me. Finding a schematic or guide is vexing though. Any clues, hints or other ideas from you fine smart folk?

[Cebus Capucinis]

:o don't break my computer!!! hahaha

 

Oh, wait, it's yours, do what you want with it. Use it as a doorstop! Eat breakfast off it! You're the WINNER!

 

BTW it is packed and ready to go out!

[nathanallan]

Had to give a +1 to both of you, AB Positive for wanting to upgrade the awesome 520ST and Cebus for the "DON'T break my computer" joke. :rolling:

 

Wish I had more to contribute, but I still haven't upgraded mine, yet. You may want to ask longhornengineer to do it, he's great at that kind of thing.

[AllanHiggins]

So I got lucky and won a stock 520ST ... how hard would a RAM upgrade be?

 

 

Depends upon your motherboard (I'll call it a motherboard, but it's likely the only board in the machine). I had a 520 back in Canada about 20 years ago, and when I opened it up I found that the board already had the circuits laid out for the extra RAM. Maybe it was a late model 520 and was simply a 1040 missing the RAM, I don't know, but it was a lucky break. I added the chips which I bought from a local electronics store, and a couple of diodes or resistors (I forget which, but there were already spaces for those too and they were clearly labelled).

 

I shouldn't actually make it sound that easy, though it should have been easy if I was more skilled with the soldering iron. I had to do the whole thing twice, because the first time I tried it I soldered the chips directly onto the board, and fried some of them because of the heat from the soldering iron. I un-soldered and replaced them with sockets, into which I then plugged a new set of chips. *THEN* it worked. If I were to do it again today I could likely avoid the sockets just by using the proper heat sinks or simply just by avoiding soldering all the pins on a chip at once - solder one pin, then move onto the next chip, solder one pin, etc. just to give the chip a chance to shed some heat before you get back to it.

 

 

[+save2600]

Be nice if there was a simpler upgrade path for those of us unlucky enough NOT to have the more 1040 like mobo. Was there not a RAM expansion for the cartridge port? How difficult would it be to fabricate one? I'm not familiar enough with the architecture of the machine, if the appropriate bus lines are there or not.

Edited March 8, 2010 by save2600

[Lynxman]

If you only need 1MB in total, the piggyback is the best solution for the 520ST. (without freaking F/FM/E )

It is the same what Atari did at the 520ST+

 

You only need to take care about the /RAS and /CAS lines. You need 16 chips 256Kx1 (120ns or faster) and 3 resistors (33 or 68 Ohm, i can not clear remember) and some wire.

 

I have done this 3 times (520ST/M), and 1 time i did it with a 1040STFM, 32chips piggyback. But for this you need additional some TTL chips to connect the 4 RAM banks (512K each) to 1 RAM bank (2MB).

I do not clear remember, but i used 3 TTL chips to do this. I added a 2MB extansion (16 chip solution) to get 4MB and i remember that the power supply was always very hot. Sometimes at very hot days in the summer, the ST stopped working after 15 minutes. But this is a different story...

Edited March 8, 2010 by Lynxman

[AB Positive]

:o don't break my computer!!! hahaha

 

It's not called 'Breaking' it's called "Improving... through brute force stupidity"

 

Hmm... TTL chips you say? I think I need to find schemata for both, there's a chance doing the SIMM-slot upgrade might actually be easier

[Cebus Capucinis]

Maybe I'll give you a couple C64s to practice on first, nobody cares if those break :lol:

[puppetmark]

So I got lucky and won a stock 520ST from Cebus' raffle. Being the amateur hacker that I am, I'd love to mod the puppy up when I get it.

 

Question is - how hard would a RAM upgrade be? I've seen the SIMM mods floating about, but that might be a bit much even for me who does have (some) soldering experience.

 

I've heard of doing piggybacks or DRAM replacing... I did a similar thing to make a 64K 600XL and that idea doesn't bother me. Finding a schematic or guide is vexing though. Any clues, hints or other ideas from you fine smart folk?

 

Here is a link to a 4MB SIMM upgrade:

http://newsgroups.derkeiler.com/Archive/Comp/comp.sys.atari.st/2005-07/msg00519.html

 

Some other upgrades including RAM:

http://atari4ever.free.fr/

[+save2600]

Maybe I'll give you a couple C64s to practice on first, nobody cares if those break :lol:

 

Hey now! You're lucky there isn't a -1 type integer button...

[oky2000]

From memory ALL ST and STM machines were able to be upgraded to 2.5mb of RAM by various companies selling the original ST without the built in drive at the time so it must be possible for all to have just a simple 512k upgrade.

 

I think I remember UK Atari User running a tutorial on piggybacking the existing ram chips with a 2nd one and the various wiring mods to make it work (some resistors or caps on each one added IIRC) I'll see if I can dig up the article in the appropriate issue and scan it for you.

 

I'm lucky enough to have three 520STs myself, don't care much for the bloated STF chassis they forced on us....I might be persuaded to sell one for the right price.

[Lynxman]

From memory ALL ST and STM machines were able to be upgraded to 2.5mb of RAM by various companies selling the original ST without the built in drive at the time so it must be possible for all to have just a simple 512k upgrade.

 

If a IMP-MMU is installed, it is not possible to work with 2,5MB.

[oky2000]

From memory ALL ST and STM machines were able to be upgraded to 2.5mb of RAM by various companies selling the original ST without the built in drive at the time so it must be possible for all to have just a simple 512k upgrade.

 

If a IMP-MMU is installed, it is not possible to work with 2,5MB.

 

 

All I know is that in the days before the STFM that people were offering 2.5mb 520ST and 520STM and 4mb 1040STF to everyone regardless of age of machine.

 

edit: It wasn't a kit it was an upgrade service so I am sure they would replace the MMU if required at those prices

Edited March 12, 2010 by oky2000

[+wood_jl]

"Back in the day" I had a 1040STf with 4MB. It was "Z-RAM" (so they called it) mod. I sent the computer away (can't remember where) I think it was to "Zubair Interfaces" or some similar-sounding name. I never opened it to look - which I'm kind of sorry about.

 

I am thinking it was some kind of kludge that went under the MMU or something like that - but it's been so long and I am not very technical that I could have this goofed.

 

 

I think a 520STm with 1MB (or more) would be a nice machine! Perhaps there is a "how-to" doc file somewhere? Are the RAM chips to do this still available? I am doubtful that "Z-RAM" type prefabbed expansions are available anymore, eh? I'll bet if there are any expansions available, they only cater to f/fm models....

 

Other than for having a huge RAMdisk, is there a lot of use for more than 1MB nowdays? Will most games work in 1MB or even 512k? Been out of the ST scene for a long, long time.

Edited March 13, 2010 by wood_jl

[oky2000]

"Back in the day" I had a 1040STf with 4MB. It was "Z-RAM" (so they called it) mod. I sent the computer away (can't remember where) I think it was to "Zubair Interfaces" or some similar-sounding name. I never opened it to look - which I'm kind of sorry about.

 

I am thinking it was some kind of kludge that went under the MMU or something like that - but it's been so long and I am not very technical that I could have this goofed.

 

 

I think a 520STm with 1MB (or more) would be a nice machine! Perhaps there is a "how-to" doc file somewhere? Are the RAM chips to do this still available? I am doubtful that "Z-RAM" type prefabbed expansions are available anymore, eh? I'll bet if there are any expansions available, they only cater to f/fm models....

 

Other than for having a huge RAMdisk, is there a lot of use for more than 1MB nowdays? Will most games work in 1MB or even 512k? Been out of the ST scene for a long, long time.

 

The extra memory would be great for sampling or sequencing in MIDI etc or even animation packages....2.5mb is a lot. A lot of games work fine in 1mb and there are probably some early games that require 512k only but because Atari was so quick to get the 1040STF out it isn't really a problem as a percentage of games released I bet.

 

You do still get the chips here and there but that's from salvage machines. When I get a chance I'll pop a scan of the relevant 'piggyback' mod to get 1mb into an early STFM or STM/ST machine....haven't found it yet to scan it.

[AB Positive]

You do still get the chips here and there but that's from salvage machines. When I get a chance I'll pop a scan of the relevant 'piggyback' mod to get 1mb into an early STFM or STM/ST machine....haven't found it yet to scan it.

 

This would be cool - 1MB is really enough for me right now with maxYMizer, and it's always neat to see souped up classics.

[AB Positive]

So, cancel my first question. I got the ST, it works great... and it's misbadged. It's not a 520ST, it's a 520STm. It has the RF modulator in there! Says STm on the bottom too - BONUS.

 

Now... uh... does this make my hardware hacking harder or easier?

[mellis]

So, cancel my first question. I got the ST, it works great... and it's misbadged. It's not a 520ST, it's a 520STm. It has the RF modulator in there! Says STm on the bottom too - BONUS.

 

Now... uh... does this make my hardware hacking harder or easier?

 

Harder, I'm afraid.

 

There's not a whole lot of room inside of a 520STm. The 520STfm is roomy by comparison.

[AB Positive]

d'oh!

 

Well I'm really mainly looking to get to 1MB, so I guess I'll start searching for the 'piggyback' method.

[mimo]

did you open it up yet?

iirc some ST motherboards had the spaces for the extra bank of memory. I think Flashjazzcat did this mod last year. Posted his progress in this forum somewhere

 

here you go link

Edited March 18, 2010 by Preppie!!

[mellis]

did you open it up yet?

iirc some ST motherboards had the spaces for the extra bank of memory. I think Flashjazzcat did this mod last year. Posted his progress in this forum somewhere

 

here you go link

 

His was a 520STfm.

[+save2600]

My 520STm does not have the extra solder holes for 1mb of RAM, so I may end up doing the piggyback mod someday.

[+wood_jl]

Well, here's a thread from 2004 on Atari-forum that gives a little info, but it's far from instructions about how to do this mod.

 

http://www.atari-forum.com/viewtopic.php?f=15&t=2904&p=31664

 

I'm pretty far from a technician, but if I had some clear instructions and materials, I would like to try this. The old 520ST is my favorite model in the whole bunch of them that came after the 8-bits. To have 1MB would be awesome. I remember the Atari dealer (Anchorage, AK) doing these mods all day long, every business day, back in 1985-1987 or thereabouts. I remember watching (but not paying attention) to Scott Peterson do this to his own 520ST back then. Everybody was doing it!!!

 

But now, it seems a rather elusive upgrade; these machines have been overshadowed by the STfm series, that's for sure!

 

I have never heard of the old 520ST with more than 1MB, and fortunately that's enough for games, etc. But can someone more technical explain why the STfm series - while officially closed/non-expandable - got so many more mods? Is the fact that the motherboard's bigger what allows for it? Did they change the MMU? When you install one of those SIMM upgrades, do you disable the DRAM chips that are on your motherboard and use the SIMM exclusively?

 

Those SIMM upgrades that are common for STfm series - they will not work in 520ST?

 

Thanks, as always!

[Lynxman]

 

Those SIMM upgrades that are common for STfm series - they will not work in 520ST?

 

 

yes

[+wood_jl]

 

Those SIMM upgrades that are common for STfm series - they will not work in 520ST?

 

 

yes

 

Thank you! Can you tell me where these are available, and what they are called? Would they come with instructions for the old 520ST?

 

 

It is not looking good for 520ST/520STm memory upgrades, at all.

 

1) I can not find any information on the web - like a TXT file or a PDF or anything - not even a forum message - that details how to do this.

 

2) I emailed Best Electronics and asked about the "piggyback" method and they replied:

 

A. Our Atari 25+ year Super Tech does not recommend this 520ST Ram Upgrade. When they do go bad (and they do) they are about impossible to repair. Our Super tech will not even touch one that comes in for repair.

 

This is not encouraging. I remember EVERYBODY doing this in 1985. Maybe if the original RAM was socketed and then the piggybacks could be pulled and replaced if they went bad? It's rather difficult to reconcile something that was so common in '85 is so elusive today, unless the RAM chips are not available. As I haven't poked around the ST in so many years, I can't recall what type to start searching for. Aren't there jumpers from some of the piggyback chips to the MMU? Man, where is this upgrade published?

 

Perhaps it is best to reactivate some dead threads on Atari-forum, as there's virtually no traffic in the ST forum here.

Edited March 25, 2010 by wood_jl