COPPER
The Copper has 3 instructions, so it is a very simple little processor, but combined with the other aspects of the Amiga and the ability of the Copper to write data into many hardware registers make it a powerful little beast in the Amiga.
The instructions are: WAIT, MOVE and SKIP.
Of these SKIP is very rarely used, most of the things can be made with just the WAIT and MOVE instructions.
- WAIT can wait for a specific rasterline vertically and on an OCS (Original ChipSet) Amiga the horizontal resolution is in lowres 4 px, highres 8 px.
- MOVE can move a word of data (16-bits), used to move data into dataregisters of the special chips.
SYNTAX:
- WAIT <beamposition>,<mask> both <beamposition> and <mask> are 16-bit words, so the CPU can address these as a 32-bit longword pair
- MOVE <address>,<data> here too <address> and <data> are 16-bit, and the CPU can address them as a pair
WAIT <beamposition>,<mask>
Timing: 4 cycles
FIRST WAIT INSTRUCTION WORD (IR1)
-----------------------------------------------------------------------------
Bit 0 Always set to 1.
Bits 15 - 8 Vertical beam position (called VP).
Bits 7 - 1 Horizontal beam position (called HP).
SECOND WAIT INSTRUCTION WORD (IR2)
-----------------------------------------------------------------------------
Bit 0 Always set to 0.
Bit 15 The blitter-finished-disable bit . Normally, this
bit is a 1. (See the "Advanced Topics" section below.)
Bits 14 - 8 Vertical position compare enable bits (called VE).
Bits 7 - 1 Horizontal position compare enable bits (called HE).
MOVE <address>,<data>
Timing: 4 cycles
FIRST MOVE INSTRUCTION WORD (IR1)
---------------------------------
Bit 0 Always set to 0.
Bits 8 - 1 Register destination address (DA8-1).
Bits 15 - 9 Not used, but should be set to 0.
SECOND MOVE INSTRUCTION WORD (IR2)
-----------------------------------------------------------------------------
Bits 15 - 0 16 bits of data to be transferred (moved)
to the register destination.
SKIP <beamposition>,<mask>
Timing: 6 cycles
FIRST SKIP INSTRUCTION WORD (IR1)
-----------------------------------------------------------------------------
Bit 0 Always set to 1.
Bits 15 - 8 Vertical position (called VP).
Bits 7 - 1 Horizontal position (called HP).
Skip if the beam counter is equal to or
greater than these combined bits
(bits 15 through 1).
SECOND SKIP INSTRUCTION WORD (IR2)
-----------------------------------------------------------------------------
Bit 0 Always set to 1.
Bit 15 The blitter-finished-disable bit .
Bits 14 - 8 Vertical position compare enable bits (called VE).
Bits 7 - 1 Horizontal position compare enable bits (called HE).
This page will be updated with more information and a new layout.....