Changes
/* Technical */
* Uses a 8KB static RAM paged into memory at &c000.
* ROM is paged into the range &0000-&3fff when the red button is pressed and the NMI vector is executed.
* Black When the black button pages their is pressed, the ROM is paged into the range &0000-&3fff and executes it at &0000. This checks the BASIC ROM version, and clears the extra ram if a CPC6128 BASIC ROM from a CPC6128 is found.
0000 f3 di ;; disable maskable interrupts
