Allocating Memory For Bit-Planes; Table 3-7 Playfield Memory Requirements, Ntsc - Commodore Amiga A1000 Hardware Reference Manual

ALLOCATING MEMORY FOR BIT-PLANES

After you set the number of bit-planes and specify resolution modes, you are ready to
allocate memory. A bit-plane consists of an end-to-end sequence of words at consecutive
memory locations. When operating under the Amiga operating system, use a system call
such as AllocMem() to remove a block of memory from the free list and make it available
to the program. If the machine has been taken over, simply reserve an area of memory
for the bit-planes. Next, set the bit plane pointer registers (BPLxPTH/BPLxPTL) to point to
the starting memory address of each bitplane you are using. The starting address is the
memory word that contains the bits of the upper left-hand corner of the bit-plane.
Table 3-6 shows how much memory is needed for basic playfields. You may need to
balance your color and resolution requirements against the amount of available memory
you have.
Table 3-7: Playfield Memory Requirements, NTSC
Picture Size
320 X 200
320 X 400
640 X 200
640 X 400
Modes
Low-resolution,
non-interlaced
Low-resolution,
interlaced
High-resolution,
non-interlaced
High-resolution,
interlaced
- 46 Playfield Hardware -
Number of Bytes
per Bit-Plane
8,000
16,000
16,000
32,000