NES Game Programming Tutorial279

Introduction

In this tutorial, we'll cover the basics of NES game programming in assembly language. We'll start with a brief overview of the NES hardware and then move on to writing our first program.

NES Hardware Overview

The NES is an 8-bit game console released in 1983. It has a 6502 CPU, 2KB of RAM, and 2KB of VRAM. The graphics are displayed on a 256x240 pixel screen, and the sound is generated by a single-channel PSG (Programmable Sound Generator).

Writing Our First Program

For our first program, we'll create a simple "Hello, World!" program. To do this, we'll need a text editor and an NES assembler. Once we have those, we can create a new file and type in the following code:```
; Hello, World! program for the NES
.org $C000 ; Start of program memory
LDA #$80 ; Load $80 into the A register
STA $0200 ; Store the A register at address $0200
LDX #$00 ; Load $00 into the X register
LDY #$03 ; Load $03 into the Y register
LDA ($0200),Y ; Load the value at address $0200+Y into the A register
CMP #$80 ; Compare the A register to $80
BEQ done ; If the A register is equal to $80, branch to the "done" label
JMP start ; Otherwise, jump to the "start" label
done:
RTS ; Return from subroutine
start:
JMP start ; Jump to the "start" label
```

This program will print the string "Hello, World!" to the screen. Here's a brief overview of how it works:
The .org $C000 directive tells the assembler to start the program at address $C000.
The LDA #$80 instruction loads the value $80 into the A register.
The STA $0200 instruction stores the value in the A register at address $0200.
The LDX #$00 instruction loads the value $00 into the X register.
The LDY #$03 instruction loads the value $03 into the Y register.
The LDA ($0200),Y instruction loads the value at address $0200+Y into the A register.
The CMP #$80 instruction compares the A register to the value $80.
The BEQ done instruction branches to the "done" label if the A register is equal to $80.
The JMP start instruction jumps to the "start" label if the A register is not equal to $80.
The done label is the end of the program.
The RTS instruction returns from the subroutine.
The start label is the start of the program.

Next Steps

This is just a very basic introduction to NES game programming. To learn more, I recommend checking out the following resources:

2024-12-17

Previous：AI Software Self-Learning Tutorial: Unleashing the Power of Artificial Intelligence

Next：Omm Measurement Programming Tutorial