* Address not writable by the Copper.
Address
not
writable by the Copper unless COPCON is set true.
A,D,P
A=Agnus
chip, D=Denise chip,
P=Paula
chip.
W,R
W write;
R=read,
ER
Early read. This is a DMA
data
transfer
to
RAM, from either the disk or the
blitter. RAM timing requires
data
to
be on the bus earlier than microprocessor
read cycles. These transfers are therefore initiated by Agnus timing, instead of a
read address on the destination address bus.
S Strobe (write address with no register bits).
PTL,PTH
IS-bit pointer
that
addresses DMA data. Must be reloaded by a processor
before use (vertical blank for bit-plane and sprite pointers, and prior
to
starting
the blitter for blitter pointers).
LCL,LCH
IS-bit location (starting address) of DMA data. Used
to
automatically restart
pointers, such as the Copper program counter (during vertical blank) and the
audio sample counter (whenever the audio length count
is
finished).
MOD
B-2
IS-bit modulo. A number
that
is automatically added
to
the memory address
at
the end of each line to generate the address for the beginning of the next line.
This allows the blitter (or the display window)
to
operate on (or display) a win-
dow of
data
that
is
smaller than the actual picture in memory (memory map).
Uses
15
bits, plus sign extend.
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