* Uses a 16KB ROM paged into memory at &0000.
* Uses a 8KB static RAM paged into memory at &c000-&dfff and repeats again at &e000-&ffff.
* ROM is paged into the range &0000-&3fff when the red button is pressed (this causes an [[NMI]]).
* When the black button is pressed the ROM is paged into the range &0000-&3fff and executes it at &0000. (this is a reset)
This checks the BASIC ROM version, and clears the extra ram if a BASIC ROM from a CPC6128 is found.