520 ST NTSC RAM Upgrade (no internal floppy drive)

[walter_J64bit]

OK, with 1040STFM being dead I'm looking to get the 520ST I have a RAM Upgrade to 1.5 or higher, what do I need?

[GadgetUK]

Hmmm, I think your options are limited. If you don't mind soldering tonnes of wires and provided you can get the right SIMM, it should be possible to install a 2 or 4Mb SIMM. The 2Mb can be soldered in to give 2.5Mb if memory serves, or you can disable the 512Kb and solder in a 4Mb SIMM. They are the 72 pin variety and need to be fast page SIMMs. Techie Alison posted guides and stuff on atari-forum on the subject. Beware though, its a complex mod with ~70+ wires.

 

You might also be able to piggyback DRAM chips over the existing 512Kb - if you can find some good 41256, 51256 or 81256 chips 80nS or faster. Not sure the original ST had space for more than 512Kb.

 

Before you do anything, search for the Marpet Xtra RAM pdf and have a read - I dont know if that will work with your revision, if it does and you have the right chips alteady socketed (MMU and shifter), and theres enough internal space, then that would be the easiest option, and they are cheap on EBAY and use 30pin 1Mb SIMMs.

Edited August 5, 2013 by GadgetUK

[walter_J64bit]

I know I can't do the 72 pin mod my hands are to shaky, you have a link I want take look anyway.

You have links all the upgrades your talking about?

Edited August 5, 2013 by walter_J64bit

[GadgetUK]

I know I can't do the 72 pin mod my hands are to shaky, you have a link I want take look anyway.

You have links all the upgrades your talking about?

 

 

Marpet (start with this, if your board supports it its by far the cheapest and easiest option and will give you 4Mb).

 

http://dev-docs.atar...es/Xtra-RAM.pdf

 

512Kb to 1Mb (doubt you can do this on your PCB, it won't have space for the chips:-

 

http://exxos.www.idn...t/ram/index.htm

 

4Mb 72 pin SIMM (same methods apply for 2Mb SIMM)

 

http://www.atari-for...hp?f=15&t=13905

 

Another useful thread:-

 

http://www.atari-forum.com/viewtopic.php?f=15&t=18978

Edited August 5, 2013 by GadgetUK

[walter_J64bit]

Thanks!

[Chandler]

_{for the 520 ST (no internal floppy drive / external PSU) there is very limited space inside and the Marpet does not fit}

 

_{i do have a 2mb Frontier upgrade that does fit, all tested and working with manual}

 

_{so adding that to your 512k will give you 2.5mb}

 

_{all depends if your 520 will accept the upgrade (as there was a weird MMU chip that didn't work with upgrades)}

 

_{£25 plus shipping}

 

_{PM me if you're interested}

[walter_J64bit]

In coming PM!