exxos's Atari, Amiga & retro forum

In 2004 while also tweaking the 1.44 floppy kit as talked about also, I designed a 72pin simm upgrade for the STFM as illustrated above.

This board was large and fitted into the shifter socket. The shifter itself went on top of the PCB. The signals from the MMU were taken from the resistor rows. This saved having anything pushed into the MMU socket.

Later a small revision to have a horizontal simm socket... ..and a rear image of the PCB found just this week!... Only a handful (less than 10) of these were ever produced. Maybe one or 2 still lives in the wild somewhere, I have no idea.

I basically abandoned this design as it only fits on one revision motherboard. I later found out that even if the revision looks like the same layout, the MMU and resistors can be just 5mm to the left than other revisions. So it proved that better solutions were needed.

The PCB version was built around 2004. But, My first real prototype was converting the STE's RAM layout to the STFM around 1998. This one made it to a "one off" prototype in 2001. It actually worked really well.

At the time it was to much effort to deal with 4 simms, so a 72pin simm prototype was done. This actually worked really well also

Of course later in 2012 I designed a new "T-Board". This board is coming to end of production since its proved to difficult for most to de-solder the old RAM and solder in the PCB once built. Most are going for my MMU STYLE board instead. So this simm board is basically discontinued now. At the time of typing there is still a few on sale in my store. Though I do have around 30 PCB's left still. Though I do not plan on producing kits of these anymore. I may use these boards in machines which I upgrade for sale in the future though as they are a low cost solution overall. Just a lot of work


4MB MMU STLYE WEBPAGE
http://www.exxosforum.co.uk/atari/last/4MBMMU/index.htm

STORE LINK
https://www.exxosforum.co.uk/atari/store2/#0035

4MB SIMM WEBPAGE
http://www.exxosforum.co.uk/atari/last/4mb/index.htm

STORE LINK
https://www.exxosforum.co.uk/atari/store2/#0020