The Oomparison Enable Bits; Using The Copper Registers; Looation Registers - Commodore Amiga Hardware Reference Manual

THE COMPARISON ENABLE BITS
Bits 14-1 are normally set to all Is. The use of the comparison enable bits is described
later in the "Advanced Topics" section.
Using the Copper Registers
There are several machine registers and strobe addresses dedicated to the Copper:
o Location registers
o Jump address strobes
o Con trol register
LOCATION REGISTERS
The Copper has two sets of location registers:
COP1LCH High 3 bits of first Copper list address.
COP1LCL Low 16 bits of first Copper list address.
COP2LCH High 3 bits of second Copper list address.
COP2LCL Low 16 bits of second Copper list address.
In accessing the hardware directly, you often have to write to a pair of registers that
contains the address of some data. The register with the lower address always has a
name ending in "H" and contains the most significant data, or high 3 bits of the
address. The register with the higher address has a name ending in "L" and contains
the least significant data, or low 15 bits of the address. Therefore, you write the 18-bit
address by moving one long word to the register whose name ends in "H." This is
because when you write long words with the 68000, the most significant word goes in the
lower addressed word.
In the case of the Copper location registers, you write the address to COP1LCH. In the
following text, for simplicity, these addresses are referred to as COPILC or COP2LC.
Coprocessor Hardware 13