Atari 520ST - Best way to upgrade the RAM?

[ColecoGamer]

I discovered a RAM expansion on eBay that comes with 4megs of Ram. Its a thin, red board with 2 memory chips on it.

 

According to a video made by Adrian’s Basement, that board is far more reliable than the one that takes Simms. He states the Simm board cracks the MMU socket when installed and its pretty finicky.

 

Can anyone recommend a RAM expansion for my 520ST and also provide an honest, reputable source to install it here in the States? My soldering skills are novice at best and I don’t want to damage the ST.

 

Thank you for looking and responding!

 

I have considered upgrading to a 1040ST/STE, but my 520ST has an internal Gotek drive fitted inside the floppy drive bay, and it was a pain to install. I cringe at the thought of removing it from the 520ST and installing it inside a new one.

Edited March 1, 2023 by ColecoGamer

[+remowilliams]

Upgrades that jam into the MMU socket are somewhat less than ideal for a few reasons.

 

I installed an agranlund/STRam type board (the board you are describing) into my 520STm and would recommend that upgrade.  It does however require fairly advanced (de)soldering skills or board destruction will result.

[snarkdluG]

Make sure you have the right motherboard for the ram board you are planning to install. 

[masteries]

 

There are some 520 ST models with free places for another 512 KB of RAM,

while others need to use piggyback method to upgrade to 1 MB

 

Regarding special expansions that let more than 1 MB of RAM for standard ST machines,

I have no experience for these expansions.

Edited March 1, 2023 by masteries

[TZJB]

On 3/1/2023 at 3:38 AM, ColecoGamer said:

I discovered a RAM expansion on eBay that comes with 4megs of Ram. Its a thin, red board with 2 memory chips on it.

 

According to a video made by Adrian’s Basement, that board is far more reliable than the one that takes Simms. He states the Simm board cracks the MMU socket when installed and its pretty finicky.

 

Can anyone recommend a RAM expansion for my 520ST and also provide an honest, reputable source to install it here in the States? My soldering skills are novice at best and I don’t want to damage the ST.

 

Thank you for looking and responding!

 

I have considered upgrading to a 1040ST/STE, but my 520ST has an internal Gotek drive fitted inside the floppy drive bay, and it was a pain to install. I cringe at the thought of removing it from the 520ST and installing it inside a new one.

You don't say what model of Atari ST you own. The RAM expansion that you speak of is motherboard specific for an original Atari ST. There are many variations of motherboard and this upgrade does require removal of all the original RAM which is a lot of work. Unfortunately, Atari ST RAM upgrades do require a fair amount of soldering/desoldering for a reliable solution.

 

I previously had a 2MB Frontier upgrade sitting in my Atari 1040STF but I did find that the MMU adapter was unreliable when the Atari STF was moved around (I used it for Midimaze tournaments) so I went back to stock on that machine.

 

I now have a Marpet Xtra-RAM Deluxe with 2MB SIMM upgrade in Bank 1 that I bought attached to a faulty Atari 520STFM motherboard from a seller on eBay UK.

The Xtra-RAM MMU cable had the MMU adapter cut off and was soldered directly to the motherboard making it virtually non-transferable. This installation method was chosen because the MMU was a soldered type and had no socket to mount the MMU adapter to, but this does make it extremely reliable. Lucky for me the motherboard worked fine too! I then followed the Marpet user manual to disable the on-board 512KB RAM, and installed 2 extra 1 MB SIMMS in the upgrade board to make a 4MB STFM.

 

I can therfore recommend the Marpet Xtra-RAM deluxe with 4MB SIMMS expecially when soldered in as the existing RAM stays in situ but is disabled. However I am waiting for @tf_hh to market his 4MB solution which is similar in concept to the soldered in Marpet Xtra-RAM deluxe. See http://www.van-radecke.de/STUFF/tfhh_HW_info.pdf. Like the Marpet solution the existing RAM is disabled and this upgrade can be used in any Atari ST/F/M and MegaST.

 

I have also come across a DIY variant of the Marpet 4MB upgrade which I attach and may be considered. It is also a good explanation of what the commercial upgrades are doing too.

 

I hope this helps and that you find a solution that suits you, but it's not an easy upgrade.

 

Incidentally a good reason for additional RAM is to allow a hard drive or modern equivalent to run. They require driver programs, so the more RAM you can have the better.

 

 

520ST_4Mb_RAM_upgrade.pdf

Edited March 2, 2023 by TZJB

[TimC]

I ordered 5 of the boards Adrian used in that video from JLCPCB.  I happened to find 1 SIMM that had the two memory chips on it needed for this upgrade.  I was able to install it into my 520ST pretty easily since I have a desoldering gun.  It seems to be running great for me.  I also updated to EmuTOS and installed a Gotek inside the case as well.

 

As others have said, you need to make sure it will work with your motherboard revision.  Looking at Marpet and other 4MB upgrade procedures, this one seems to be the easiest (IMO).

 

I am near Chicago.  PM me if you are interested in having me attempt the upgrade for you.

[ColecoGamer]

11 hours ago, TZJB said:

You don't say what model of Atari ST you own. The RAM expansion that you speak of is motherboard specific for an original Atari ST. There are many variations of motherboard and this upgrade does require removal of all the original RAM which is a lot of work. Unfortunately, Atari ST RAM upgrades do require a fair amount of soldering/desoldering for a reliable solution.

 

I previously had a 2MB Frontier upgrade sitting in my Atari 1040STF but I did find that the MMU adapter was unreliable when the Atari STF was moved around (I used it for Midimaze tournaments) so I went back to stock on that machine.

 

I now have a Marpet Xtra-RAM Deluxe with 2MB SIMM upgrade in Bank 1 that I bought attached to a faulty Atari 520STFM motherboard from a seller on eBay UK.

The Xtra-RAM MMU cable had the MMU adapter cut off and was soldered directly to the motherboard making it virtually non-transferable. This installation method was chosen because the MMU was a soldered type and had no socket to mount the MMU adapter to, but this does make it extremely reliable. Lucky for me the motherboard worked fine too! I then followed the Marpet user manual to disable the on-board 512KB RAM, and installed 2 extra 1 MB SIMMS in the upgrade board to make a 4MB STFM.

 

I can therfore recommend the Marpet Xtra-RAM deluxe with 4MB SIMMS expecially when soldered in as the existing RAM stays in situ but is disabled. However I am waiting for @tf_hh to market his 4MB solution which is similar in concept to the soldered in Marpet Xtra-RAM deluxe. See http://www.van-radecke.de/STUFF/tfhh_HW_info.pdf. Like the Marpet solution the existing RAM is disabled and this upgrade can be used in any Atari ST/F/M and MegaST.

 

I have also come across a DIY variant of the Marpet 4MB upgrade which I attach and may be considered. It is also a good explanation of what the commercial upgrades are doing too.

 

I hope this helps and that you find a solution that suits you, but it's not an easy upgrade.

 

Incidentally a good reason for additional RAM is to allow a hard drive or modern equivalent to run. They require driver programs, so the more RAM you can have the better.

 

 

520ST_4Mb_RAM_upgrade.pdf 3.42 MB · 7 downloads

Even the Marpet requires the user to disable the on-board RAM? Gee. I own a later model of the 520ST, with a built-in floppy drive (which was replaced with a Gotek) and an internal power supply.

Edited March 3, 2023 by ColecoGamer

[+remowilliams]

56 minutes ago, ColecoGamer said:

Even the Marpet requires the user to disable the on-board RAM? Gee. I own a later model of the 520ST, with a built-in floppy drive (which was replaced with a Gotek) and an internal power supply.

The agranlund/STRam type board isn't for you then.  It's for the 520ST not the 520STF.

 

Yes even the Marpet will require disabling onboard RAM depending on the config.  This involves clipping one end of some resistors and wiring them to 5V.

[TZJB]

14 hours ago, ColecoGamer said:

Even the Marpet requires the user to disable the on-board RAM? Gee. I own a later model of the 520ST, with a built-in floppy drive (which was replaced with a Gotek) and an internal power supply.

 

Yes disabling the internal RAM is very easy. Much easier than removing all the RAM, and can subsequently be reverted back to stock without any damage.

 

It involves holding the CAS lines high at 5 Volts by cutting the high and low CAS resistors for each bank at the MMU side and tying them to 5V towards the RAM. See the user manual extracts. Sorry about the quality it's all I have.

 

I would always recommend a soldered solution for stability. Just run a wire from the resistors to any suitable decoupling capacitor with 5V.

 

 

Regarding your Atari ST, you must have a 520STFM (Floppy/Modulator) as only the 1040STF or MegaST didn't have a modulator from memory.

 

[snarkdluG]

A very good resource is https://docs.dev-docs.org/ for manuals and schematics. Search for  Marpet/Frontier. 

[+DarkLord]

1 hour ago, TZJB said:

 

Regarding your Atari ST, you must have a 520STFM (Floppy/Modulator) as only the 1040STF or MegaST didn't have a modulator from memory.

 

 

And STacy...  

 

[ColecoGamer]

I would like to thank everyone who responded. I have some reading to do on the subject!

[swatcop]

I recently acquired a STF from a friend of mine that had a Marpet X-Tra RAM kit installed (2.5 mb).  Was frankly not expecting it to work with all the negative things you hear about the Marpet.  When it turned out to actually be working, I upgraded it to a full 4 mb by installing another couple RAM sticks and disabling the second bank of motherboard memory (pretty easy actually). I have been pleasantly surprised at how well it works and its reliability.  I did a bunch of upgrades while I was at it (RAM, designed a 3d printed bracket to hold the Marpet, RGBtoHDMI, GOTEK, Meanwell PSU, 3.5mm audio out, and socketed CPU for an AdSpeed 16 MHz accelerator).

 

I was going to buy the Exxos memory upgrade board, but this works so well that I'm keeping it.  You might want to check out the Exxos memory upgrade too since the agranlund/STRam won't work with your STF.

[TZJB]

1 hour ago, swatcop said:

I recently acquired a STF from a friend of mine that had a Marpet X-Tra RAM kit installed (2.5 mb).  Was frankly not expecting it to work with all the negative things you hear about the Marpet.  When it turned out to actually be working, I upgraded it to a full 4 mb by installing another couple RAM sticks and disabling the second bank of motherboard memory (pretty easy actually). I have been pleasantly surprised at how well it works and its reliability.  I did a bunch of upgrades while I was at it (RAM, designed a 3d printed bracket to hold the Marpet, RGBtoHDMI, GOTEK, Meanwell PSU, 3.5mm audio out, and socketed CPU for an AdSpeed 16 MHz accelerator).

 

I was going to buy the Exxos memory upgrade board, but this works so well that I'm keeping it.  You might want to check out the Exxos memory upgrade too since the agranlund/STRam won't work with your STF.

 

 

It all looks good! Great work. I did a similar upgrade to the memory as I said, except that I recapped the original PSU and put the top shielding back, with the Marpet Xtra-RAM SIMM board sitting above the shielding in the position that you have yours.

 

The Exxos ST/F/M 4MB upgrade would have fitted your Atari STF as you have a socketed MMU, but as you said, the Marpet works just fine!

 

I don't think that you could put your top shielding back however, due to your fitted upgrades. Not sure that it's needed these days anyway.

 

[ColecoGamer]

I decided to buy the Marpet and here is why: if you want to technically have a 1040ST, all you need is a single 512k simm. Doing it this way requires no modifications to the motherboard whatsoever. I want to keep the motherboard unmodified and as original as possible.

 

Now, I need to find out the type of simms the Marpet uses, if I want to go this route. 

[ColecoGamer]

Oh, I own a 520STFM. Someone asked earlier what model I own. 

[TZJB]

On 3/16/2023 at 7:54 PM, ColecoGamer said:

I decided to buy the Marpet and here is why: if you want to technically have a 1040ST, all you need is a single 512k simm. Doing it this way requires no modifications to the motherboard whatsoever. I want to keep the motherboard unmodified and as original as possible.

 

Now, I need to find out the type of simms the Marpet uses, if I want to go this route. 

I understand your thinking, but there is no such thing as a single 512KB SIMM for this application. Each SIMM is addressed as 8 bits of the 16 bit bus in either bank, so the upgrade needs at least 2 SIMMs for the second bank. Valid combinations in a 520ST/F/M/ are 2x 256KB, 2x 1MB and 4x 1MB SIMM, the latter requiring the two cut resistors to disable the onboard memory. For your application however the 2MB upgrade route would give you more scope for future upgrades and would probably cost a similar price to the 512KB with no modifications. The SIMMs are standard 30 pin 8 or 9 bit with the 9th bit unused as parity is not required.

[ColecoGamer]

3 hours ago, TZJB said:

I understand your thinking, but there is no such thing as a single 512KB SIMM for this application. Each SIMM is addressed as 8 bits of the 16 bit bus in either bank, so the upgrade needs at least 2 SIMMs for the second bank. Valid combinations in a 520ST/F/M/ are 2x 256KB, 2x 1MB and 4x 1MB SIMM, the latter requiring the two cut resistors to disable the onboard memory. For your application however the 2MB upgrade route would give you more scope for future upgrades and would probably cost a similar price to the 512KB with no modifications. The SIMMs are standard 30 pin 8 or 9 bit with the 9th bit unused as parity is not required.

Thank you for the clarification. I’ll probably go the 2mb route, since it doesn’t require any modifications to the motherboard.

 

After the memory upgrade, I plan on buying a harddrive. 👍🏻

[TZJB]

1 minute ago, ColecoGamer said:

Thank you for the clarification. I’ll probably go the 2mb route, since it doesn’t require any modifications to the motherboard.

 

After the memory upgrade, I plan on buying a harddrive. 👍🏻

That is a wise choice. I suggested the 2 MB upgrade option as that is exactly the scenario that I was thinking of. A hard drive adapter would need the extra memory to support the ACSI driver.

[ColecoGamer]

8 minutes ago, TZJB said:

That is a wise choice. I suggested the 2 MB upgrade option as that is exactly the scenario that I was thinking of. A hard drive adapter would need the extra memory to support the ACSI driver.

This is the path I will follow. Once the upgrade arrives and I install it, I’ll post a final message about everything.

 

Thank you again for the advice!

[tduck0612]

Hello Forum,

 

I have purchased an original 1985 520ST with the external power brick and FDD. I am looking for someone here in the USA that can perform a memory upgrade for me to the max 2.5MB and TOS 1.4 upgrade also. I'm not great at soldering and don't wish to fry the MB off the bat.I'm based in the Chicago area and either am looking for someone local or to ship the unit for service. Please feel free to contact me with your interested in taking on the project.