Overview

Here is how I decided and built a Silverlight Chip8 emulator.
Download ChipGr8 Source Code

What is Special About Chip8?

Chip-8 is a small interpreter created in the early 70's that has these nice features:

• Is very easy to emulate (in 4 or 5 hours you can have a working emulator!)
• Has 2d sprite drawing and pixel-perfect collision detection
• Has sound and keyboard support

If you decide to create your own emulator, chip-8 is probably one of the best to start. The "all-in-one" peripherals make it very easy to emulate the keyboard and screen.

How to Create Your Own Computer Emulator

• Decide on a programming language. C++ is fast. C# is cool and is working with Silverlight!
• Decide what you want to emulate.
  At first I started with x86 (8086) emulation - wanted to play Digger badly :)
  It turned out to be more time consuming, because of all the peripherals: PCI bus, VGA adaptor, Keyboard, Interrupt Controller, etc, etc.

After I found the chip8, it turned out it has several registers, several keyboard commands and 4K memory and 25 games!
This sounds very promising!

Source Code Architecture

This is pretty easy:

• Make a big array for the memory. In Chip8-s case I used 65536 bytes array, since this was the chip's address space
• Add a C# class for screen manipulation.
  Chip8 contains several screen commands: PutPixel() (always XOR-ed), scroll left, scroll right, scroll down.
  I decided it makes sense to put these in separate class.
• Create the class for the chip
  This is the class that contains the main variables: InstructionPointer (shows the next instruction to execute), stack, CPU registers and such.

An interesting challenge is generating the screen image using Silverlight. After searching around I found a PNG encoder for Silverlight implementation that is very usable for dynamic image generation.

Chip Architecture

For a very good explanation about the Chip8 architecture click here.

Back to ChipGr8

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