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Add Copper ISA Complete Reference Manual

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New file: 08_graphics/copper/copper_reference.md
- Full instruction set reference with opcode encoding table
- Bit-level encoding for MOVE, WAIT, SKIP (7-bit masks)
- Beam position encoding: V counter (8-bit), H counter (7-bit)
- Copper control registers (COP1LC, COP2LC, COPJMP, COPCON, DMACON)
- Copper list structure, dual lists, SKIP-based double buffering
- DMA timing budget calculations per scanline
- Register reference for all copper-writable targets
- OCS/ECS/AGA differences (AGA 24-bit color via BPLCON3 LOCT)
- Programming models: bare metal, OS-friendly UCopList, self-modifying
- Common patterns: rainbow, split screen, status bar, sprite mux
- Debugging: 8 common pitfalls with symptoms and fixes
- Mermaid fetch-execute cycle diagram

Updated files:
- 08_graphics/README.md: add copper_reference.md to index
- 08_graphics/copper/copper.md: cross-reference link, fix MOVE/WAIT
  encoding, fix UCopList CMOVE syntax
- 08_graphics/copper/copper_programming.md: cross-reference link, fix
  horizontal resolution (2 color clocks, not 4)
This commit is contained in:
Ilia Sharin 2026-06-01 14:39:43 -04:00
parent a0fc3e05db
commit 2283178f09
4 changed files with 1031 additions and 10 deletions
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21
08_graphics/copper/copper.md
View file

@ -6,6 +6,8 @@
The **Copper** is a simple coprocessor in the Amiga custom chips that executes a list of instructions synchronized to the video beam. It can write to any custom chip register at any beam position, enabling per-scanline color changes, split screens, and hardware-level display effects without CPU intervention.
For the complete ISA reference with full bit-level encoding, beam position details, control registers, timing, and debugging guidance, see **[copper_reference.md](copper_reference.md)** — the Copper ISA Complete Reference Manual.
---
## Instruction Format
@ -15,8 +17,9 @@ The Copper has only three instructions, each 32 bits (one longword):
### MOVE — Write a Register
```
[register_offset (9 bits)] [value (16 bits)]
Bit layout: 0RRRRRRRR00000000 VVVVVVVVVVVVVVVV
[register_offset] [value (16 bits)]
Word 1: 0000000R RRRRRRR0 (Offset)
Word 2: VVVVVVVV VVVVVVVV (Data)
```
- Register offset is relative to `$DFF000` (custom chip base)
@ -26,8 +29,11 @@ Bit layout: 0RRRRRRRR00000000 VVVVVVVVVVVVVVVV
### WAIT — Wait for Beam Position
```
[vpos (8 bits)] [hpos (7 bits)] [1] [vmask (7 bits)] [hmask (7 bits)] [0]
Bit layout: VVVVVVVVHHHHHH01 vvvvvvvvhhhhhhh0
[vpos (8 bits)] [hpos (7 bits)] [1]
Word 1: VVVVVVVV HHHHHHH1
[BFD (1 bit)] [vmask (7 bits)] [hmask (7 bits)] [0]
Word 2: Bvvvvvvv hhhhhhh0
```
- Pauses until the beam reaches at least the specified (vpos, hpos)
@ -86,13 +92,16 @@ The OS manages copper lists through `GfxBase`:
Applications can inject copper instructions into the system list via `UCopList`:
```c
#include <hardware/custom.h>
extern struct Custom custom;
struct UCopList *ucl = AllocMem(sizeof(struct UCopList), MEMF_PUBLIC|MEMF_CLEAR);
CINIT(ucl, 100); /* init, max 100 instructions */
CWAIT(ucl, 44, 0); /* wait for line 44 */
CMOVE(ucl, *((UWORD *)0xDFF180), 0x0F00); /* COLOR00 = red */
CMOVE(ucl, custom.color[0], 0x0F00); /* COLOR00 = red */
CWAIT(ucl, 100, 0);
CMOVE(ucl, *((UWORD *)0xDFF180), 0x000F); /* COLOR00 = blue */
CMOVE(ucl, custom.color[0], 0x000F); /* COLOR00 = blue */
CEND(ucl); /* end of list */
viewport->UCopIns = ucl;