NES Roms on Zorchenhimer.com

Animated Background

Mon, 01 Jan 0001 00:00:00 +0000

This ROM is a demonstration of an animated background that was originally apart of another game rom.

This ROM uses CHR RAM and some timed swapping of CHR banks to animate the background. The animation frames were created with Gimp and Aseprite and were designed to loop and tile seamlessly. The main animation is eight tiles high and eight tiles wide, or 64x64 pixels.

A “poor-man’s frame buffer” is utilized for the animation. Each frame one row of eight tiles are written to CHR RAM. Once eight rows have been written, the currently used background pattern table is swapped and writing rows begins on the opposite pattern table. This whole process can be accomplished with CHR ROM and 1k banks, foregoing the poor-man’s frame buffer, but the original ROM was already using CHR RAM for other purposes.

DVD Screensaver

Mon, 01 Jan 0001 00:00:00 +0000

I think this can actually hit the corner. I haven’t seen it do that though.

Famicom Brainfuck

Mon, 01 Jan 0001 00:00:00 +0000

This is a fully functional Brainfuck interpreter and compiler. The Famicom Keyboard is required to use this ROM.

There are a few example programs included with the ROM. The first is a Hello World program that just prints out that text. The second is an echo program that will echo back what is typed. This second program was used to debug and verify the engine and keyboard.

Game of Life

Mon, 01 Jan 0001 00:00:00 +0000

A short and simple implementation of Conway’s Game of Life on the NES.

Keytest

Mon, 01 Jan 0001 00:00:00 +0000

This is a utility ROM that I wrote to figure out how to read the Famicom Keyboard. I also learned the specifics of the Family Trainer mat and provided some new details for the community. I’ve got more details on the Family Trainer in its own post.

So far, I only have a few peripherals implemented, but I do plan on getting a few more in there.

The standard controller test looks for the Famicom’s built-in controllers, famicom expansion controllers, as well as the NES standard controlers and controllers plugged into a Four Score.

Parallax

Mon, 01 Jan 0001 00:00:00 +0000

This is a parallax demo using MMC3’s IRQ scanline counter and some cycle counting. The IRQ counter is the boundary between the clouds and the light blue mountains. After that triggers and updates scroll values, another IRQ is setup for the second split.

The first boundary uses some sprites overlap some mountain tops across the first boundary. The second boundary only leaves about a scanline between the two without any overlap.

Platforming

Mon, 01 Jan 0001 00:00:00 +0000

This is a simple little ROM that demonstrates some physics and collision logic that you might find in a standard side-scrolling game.

Pooh

Mon, 01 Jan 0001 00:00:00 +0000

This ROM was an exercise in CHR tile management that utilizes a Golang library that I’ve also written.

The text on both of these screens is configurable at build-time.

Pressing A will swap between the two screens, while pressing Start will toggle the screen on and off.

Snek

Mon, 01 Jan 0001 00:00:00 +0000

After writing the animated background demo with a rudimentary snake, I wanted to write a more proper snake implementation. It’s not perfect, but it’s good enough. I figure it’s about 80% complete, and that last 20% is all polish that would be a lot more work than I’m willing to put into it.

Stratagem Hero

Mon, 01 Jan 0001 00:00:00 +0000

I made a demake of the Stratagem Hero minigame from Helldivers 2!

This ROM uses the MMC5 mapper. This was my first dive into some of the MMC5’s more advanced features like the extended attribute table. The game uses the same scoring and difficulties as the minigame in Helldivers 2. The only things missing are the themed rounds and some music.