How to upgrade "Byte"?

Hi all. Gentlemen spektrumists, I recently acquired Speccy clone called "Byte" (produced by Brest Electromechanical factory). This machine has 48k, system connector, etc. There is even AY. But it is cut incorrectly, i.e. working with it is possible only through the following ports: 238 - on/off channels. 142 - 1st channel 174 - 2nd channel 206 - 3rd channel Can anyone figure out how to fix this, how to increase RAM to 128k, etc.? I would be grateful for any advice.