[Coco] Expanding 4K Coco Mem

[Jim Gerrie]

If Darren's suggestion is correct that it is the 256K line buffer and a
buffer for possible cassette data file output that explains why there is
only 2343 bytes left for a program, is there any magical set of pokes that
would allow those buffers to be "turned off" so that the mem could be used
by a program?  I think my Tetris just needs about 500 more bytes to fit.