The 1056 Board For the Atari 400 upgrades your Atari 400 to 48k of base memory plus 1008k of Axlon compatible banked memory for a total of 1056k of RAM. This greatly expands your Atari 400’s memory and allows it to run most software that is compatible with the Atari 800 as well as newer software such as SpartaDOS X.

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 The 1056 Board you do not need to "modify" the plastic inside your Atari 400's metal housing.

The images show the 1056k upgrade board, the jumper wires to be soldered to the underside of the system board, and a picture of the 1056k upgrade board installed in the system board with the CPU card.