From 279dd4b4062c6208bc2a1aca242b4ae2997da5e0 Mon Sep 17 00:00:00 2001
From: "Juan J. Martinez" <jjm@usebox.net>
Date: Mon, 1 May 2023 21:54:07 +0100
Subject: Documented current palette

---
 README.md | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

(limited to 'README.md')

diff --git a/README.md b/README.md
index d847d49..bd21d66 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ Other features:
 * programmable in ASM
 * 16-bit registers: stack pointer (SP) and program counter (PC)
 * 8-bit registers: 4 general purpose registers (a, b, x, y), flags register (F)
-* frame interrupt (60Hz) and external IO interrupt
+* frame interrupt (60Hz) and external IO interrupt (planned)
 * port based IO
 
 Memory map:
@@ -52,7 +52,7 @@ Then run `make`.
 This will result in two binaries:
 
  - **tr8as**: the TR8 assembler
- - **tr8vm**: the TR8 VM that can run `tr8` files
+ - **tr8vm**: the TR8 VM Player that can run `tr8` files
 
 You can then compile and run the example with `make example`.
 
@@ -86,7 +86,26 @@ controller 1, and `0xf1` for controller 2.
 
 ### Palette
 
-TODO: palette colors
+Current palette (not final) is the default EGA 16 colour palette:
+
+| Index | RGB (hex) |
+| --- | --- |
+| 0  | 0x000000 |
+| 1  | 0x0000aa |
+| 2  | 0x00aa00 |
+| 3  | 0x00aaaa |
+| 4  | 0xaa0000 |
+| 5  | 0xaa00aa |
+| 6  | 0xaa5500 |
+| 7  | 0xaaaaaa |
+| 8  | 0x555555 |
+| 9  | 0x5555ff |
+| 10 | 0x55ff55 |
+| 11 | 0x55ffff |
+| 12 | 0xff5555 |
+| 13 | 0xff55ff |
+| 14 | 0xffff55 |
+| 15 | 0xffffff | 
 
 ### Frame interrupt
 
@@ -128,6 +147,9 @@ int_handler:
     iret
 ```
 
+Because the flags are preserved, any code run in the interrupt handler only
+needs to preserve the 4 registers and the stack.
+
 ### Instructions
 
 All the instructions are 16-bit, with the exception of `JMP addr` and `CALL
-- 
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