RAM size, high byte only; this is the number of pages that the top of RAM represents (one page equals 256 bytes). Since there can never be less than a whole page, it becomes practical to measure RAM in those page units. This is the same value as in RAMTOP location 106 ($6A), passed here from TRAMSZ, location 6. Space saved by moving RAMSIZ or RAMTOP has the advantage of being above the display area. Initialized to 160 for a 48K Atari.

see also: RAMTOP