Hello World in PowerPC Assembly (Mac OS X)

A minimal Hello World implementation in PowerPC assembly for Mac OS X systems, targeting G3/G4/G5 processors.

Installation

Mac OS X (PowerPC)

Install the development tools from your Mac OS X installation DVD or:

# If you have Xcode installed
gcc --version  # Verify PPC support
as --version   # Verify assembler support

Building and Running

# Assemble
as hello.asm -o hello.o

# Link
ld -o hello hello.o -lSystem

# Run
./hello

Code Explanation

The program demonstrates key aspects of PowerPC assembly on Mac OS X:

Register Usage:

• r0: Volatile register, used for syscall numbers
• r1: Stack pointer
• r3: First argument/return value register
• r4: Second argument register
• r5: Third argument register
• LR (Link Register): Return address storage

System Call Interface:

• Uses sc instruction for system calls
• System call number in r0
• Arguments in r3-r5
• Stack frame must be properly maintained

Memory Addressing:

• Uses @ha/@l for loading 32-bit addresses
• Proper stack frame creation/destruction
• Saves/restores link register

Note: This implementation specifically targets PowerPC-based Mac OS X systems (10.0-10.5). The last version of Mac OS X to support PowerPC was 10.5 (Leopard).