Easiest 4mb upgrade option for Atari 520 STFM?

[macsonny]

Hi All,

 

I'm looking for a relatively simple 4 MB upgrade solution for my ST.

 

What is the current easiest solution?

 

Thanks

Sonny

 

[blacka013]

Hi Sonny,

 

have a look at this.

 

NEW Atari 520 1040 ST STF STFM Mega ST computer 4MB Marpet memory upgrade kit | eBay

 

Regards

[snarkdluG]

Exxos have similar: https://www.exxosforum.co.uk/atari/store2/#0035 

[Zogging Hell]

I've not got one but Exxos's kit looks like an easier fit in the ST, the Marpet the board needs siting on top of the metal shielding and you have to route the cables through to it. I don't know whether there is a ground wire to fit on the Exxos kit, but the Marpet needs one.

[macsonny]

Thanks for the advice. After a bit of research, some advice and a wrong order (since fixed) I have a unit for my ST on the way!

[CommodoreDecker]

On 8/23/2023 at 11:49 AM, snarkdluG said:

Exxos have similar: https://www.exxosforum.co.uk/atari/store2/#0035 

 

I noted that, for the 4mb version, regarding the 520ST's resistors but I'm also including the resistors for the 1040ST, Exxos states that R59-61 (and R71-73) have to be cut off and wire sent to +5v.  The Marpet kit from 92, which definitely is a similar design, says in its booklet that R60-61 (and R71-72).  Why would R59 and R73 be excluded from the Marpet (RAS0, if I remember the schematic correctly?)   If one has a Marpet, wouldn't it be preferred to isolate the RAS lead as well as the other two that it does document?  

 

Exxos states the RAM must be "isolated or removed" and cites "old ram must be removed after testing".  Marpet is a lot more lenient in that regard. 

 

The Marpet does state outright only the specific resistors and comes with 4 leads, so worrying about the other resistor may be a non-issue. But that does go to the onboard RAM as much as the other two do...