From 4b4a90a39a78746e0bd71e99b12cb42669af7698 Mon Sep 17 00:00:00 2001
From: xamidev <121681048+xamidev@users.noreply.github.com>
Date: Sat, 19 Oct 2024 21:25:45 +0200
Subject: [PATCH] add docs

---
 .gitignore |  1 +
 README.md  | 52 ++++++++++++++++++++++++++++++++++++++++++++++------
 cpu.c      |  3 ++-
 makefile   |  2 +-
 4 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/.gitignore b/.gitignore
index f47cb20..5293f37 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 *.out
+dumb8
diff --git a/README.md b/README.md
index 16c7933..3b98406 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,10 @@
-# UnnamedCPU
+# Dumb8-CPU
 
 Continuing my exploration of the lower-level world...
 
 This project is the implementation of a CPU in a high-level language, C. It aims to have a reduced (minimalist) instruction set and still be Turing complete.
 
-# How to test
+## How to test
 
 You can run a test program like that. I'll try making a developer's manual so one can make its own programs using the custom assembly here. 
 
@@ -13,8 +13,48 @@ make
 ./a.out program.asm
 ```
 
-# What I'd like to do
+## Technical specifications
 
-- Finish the instruction set implementation
-- Implement input/output devices (like a serial output that could be redirected to the host terminal)
-- Re-do the CPU in a Hardware Description Language, or even better: with transistors IRL! (i probably won't waste my life doing that tho)
+- 8-bit processing unit
+- RISC (reduced instruction set computer)
+- 4 general purpose registers (labeled R0 to R3)
+- 1 input port, 1 output port (via getchar and putchar)
+- Turing-completeness: bitwise and arithmetic operations
+
+## Instruction set reference (for programmers)
+
+```
+; Move register RY to register RX
+MOV RX, RY 
+
+; Arithmetic addition and substraction stored in RX
+ADD RX, RY
+SUB RX, RY
+
+; Bitwise operations stored in RX
+OR RX, RY
+AND RX, RY
+XOR RX, RY
+
+; Output RX to screen
+OUT RX
+
+; Input RX from keyboard
+IN RX
+
+; Jump to memory offset ADDR (decimal)
+JMP ADDR
+
+; Jump to memory offset ADDR (decimal) if equal flag is set by previous comparison
+JEQ ADDR
+
+; Compare RX and RY, sets equal flag if true
+CMP RX, RY
+
+; No operation; does nothing
+NOP
+
+; Halts the processing unit
+HLT
+
+```
diff --git a/cpu.c b/cpu.c
index 8518bd4..6d8d102 100644
--- a/cpu.c
+++ b/cpu.c
@@ -1,5 +1,5 @@
 /*
- * Unnamed 8-bit processing unit
+ * Dumb8 8-bit processing unit
  * Made by github.com/xamidev
  *
  * This is free and unencumbered software released into the public domain.
@@ -74,6 +74,7 @@ CPU_t cpu;
 
 void cpu_init()
 {
+	printf("Initializing Dumb8 CPU...\n");
 	cpu.pc = 0;
 	cpu.halted = false;
 	cpu.equal_flag = false;
diff --git a/makefile b/makefile
index 59003f9..e20ce02 100644
--- a/makefile
+++ b/makefile
@@ -1,5 +1,5 @@
 all:
-	gcc -g *.c
+	gcc -g *.c -o dumb8
 
 clean:
 	rm a.out