The vertical axis has co-ordinates from 0....399 which are divided by two and truncated to give a
physical position in the range 0....199. This ensures that expected aspect ratios are preserved on
screen.
Expansion ROMS
All ROMs occupy the top 16K of memory (where the the BASIC lives) and there are facilities in the
firmware to call up to 240 additional 16K add-on ROMs (a certain amount of address decoding
hardware must be employed externally to the base machine as part of the ROM expansion
hardware.)
Overview:
A brief summary of the main features of the hardware and
firmware of the CPC464.
1) Hardware
1.1) Inside the main CPC464 case.
Computer, keyboard, cassette datacorder and loudspeaker. RGB and luminance outputs.
1.1.1) LSI chips
Z80A processor running at 4MHz.
64K bytes of 64K x 1 dynamic RAM refreshed by accesses to the screen memory.
32K bytes of ROM containing BASIC and the operating system (OS).
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