The Atari 400 shipped with 16k of RAM. While adequate at that time, most Atari applications and games require at least 48k of RAM. This card replaces your RAM card and upgrades your Atari 400's main memory to a full 48k of main memory and 1008k of Axlon compatible banked memory.

Extra Axlon compatible banked memory can be used for applications that support it, games that require the extra memory, a RAM disk (or disks), SpartaDOS X, etc.

Instructions:

This upgrade requires your Atari 400 be disassembled, four jumper wires be soldered to the underside of the main board, and re-assembled. If your Atari 400 was previously upgraded with the Atari 48k RAM Expansion Kit the jumpers should already be installed.

The installation instructions, including the jumper connections are almost identical to the instructions for the Atari 48k RAM Expansion Kit and those instructions can be used and can be found here:

https://www.digitpress.com/library/techdocs/atari_400_48k_ram.pdf

Please note that the instruction differ in that with this board you do not need to "modify" the plastic inside your Atari 400's metal housing.

The images show the 1056k upgrade board and the jumper wires to be soldered to the underside of the system board.