Good question. There are upgrades up to 4mb, but ones for the 800 most common range from 64k to 1088k. A pair of really common and several less common standards have existed for many years. This one conforms to the Axlon standard, which is among the oldest for the Atari's. It switches the banks in 32k increments. The other standard was set by Atari on the introduction of the 130xe; that switches in 16k increments. Aside from a ramdisk, what can you do with it? My primary reason for building the thing is to gain memory for the Spartados X operating system, which benefits greatly from more memory (256k is the sweet spot). SDX barely runs on 48k ram and the SIDE driver does not load. SIDE2 is a cartridge for the machine that grafts a CF slot on and allows it to act as a hard disk under SDX. This is of course very useful. Here's a link to the Spartados X cooperative: http://sdx.atari8.info/index.php The Side2 cart, in addition to hosting Spartados X and the CF hard disk controller and firmware, also hosts a real-time clock, and can carry several other programs which must be hosted by hardware because of thier bank-selecting rom design, such as Basic XL, Basic XE... Spartados is a 256k bank-selected cartridge itself. Released in 1988 by ICD, Spartados X is a surprisingly rich disk operating system which adds a host of features not available on other 8-bit machines. IO redirection and batch processing, memory management, paths of various sorts... Here's a link to the Side2 cart, which comes with the SDX firmware pre- loaded: https://lotharek.pl/productdetail.php?id=55 Being able to load the SIDE driver and access the CF slot as a hard disk is my primary purpose. The machine will have ample memory to run real programs while running SDX, which is also very important. Best, Jeff On Fri, 2019-08-02 at 13:06 -0500, Eric Christopherson wrote: