o WAIT for a specific screen position specified as x and y coordinates.
o MOVE an immediate
data
value into one of the special-purpose registers
..
o SKIP the next instruction if the video beam has already reached a specified
screen position.
All Copper instructions consist of two 16-bit words in sequential memory locations.
Each time the Copper fetches an instruction, it fetches both words.
The
MOVE and
SKIP instructions require two memory cycles and two instruction words. Because only
the odd memory cycles are requested by the Copper, four memory cycle times are
required per instruction. The WAIT instruction requires three memory cycles and six
memory cycle times;
it
takes one extra memory cycle to wake up.
Although the Copper can directly affect only machine registers, it can affect the memory
by setting up a blitter operation. More information about how
to
use the Copper in
controlling the blitter can be found in the sections called "Control Register" and "Usin.g
the Copper with the Blitter."
The
WAIT and MOVE instructions are described below.
The
SKIP instruction is
described in the "Advanced Topics" section.
The
MOVE
Instruction
The
MOVE instruction transfers
data
from RAM
to
a register destination.
The
transferred
data
is
contained in the second word of the MOVE instruction; the first word
contains the address of the destination register. This procedure
is
shown in detail
in
the
section called "Summary of Copper Instructions."
FIRST INSTRUCTION WORD (IRl)
Bit 0 Always set
to
O.
Bits 8 - 1 Register destination address (DA8-1).
Bits
15
- 9 Not used,
but
should
be
set
to
O.
SECOND INSTRUCTION WORD (IR2)
Bits 15 - 0
16
bits of
data
to
be transferred (moved)
to
the register destination.
Coprocessor Hardware 9
To Next Page
Loading...
