C64 Graphics Explorer

I made a Mac app, and not just about anything: it’s about the Commodore 64. Or, more precisely, around the C64. The first version was released back in February 2026, and I’ve released a couple of updates since.

The Problem

I don’t know about you, but I like looking at C64 demos and images. I usually watch demos in an emulator, where the CRT emulation is pretty good: everything looks the way it used to on a decent monitor back in the day. But downloaded images, organized in my folders, are only visible in these tiny previews. You have to zoom in, every image has slightly different colors, you can’t see the character cells, and so on.

I think C64 pixel artwork can only be fully appreciated if you also understand how much work went into getting it onto the screen, beyond the drawing itself. That is what this little Mac app tries to help with.

Download

You can get the app from here.

How It Works

You can drop in any 16-color image and it will display it with Colodore colors and CRT emulation. If it does not guess the exact color mapping correctly, you can swap the colors manually by clicking which one should map to which. You can also move the 320×200 grid with the cursor keys, in case the image includes a border and the app did not detect its exact position.

I also thought of people who are not quite as C64-obsessed as I am, so I included a few sample images from my favorites. You can immediately get lost in the details of one classic image or another.

Motivation

There is one image I spent quite a lot of time processing.

Using the VICE monitor/debugger, I extracted the overlay and underlay sprites from the displayer, reconstructed the full rendering in Aseprite, split it into layers, and included those layers in the app so they can be toggled on and off.

One of the comments on Mermaid’s image says:

I love this. The outstanding storytelling and style is one thing. But I feel the need to tell the world how extremely well this is executed from a technical perspective. Flawless, Mermaid. Flawless.

— Archmage

Let me highlight this part:

“I feel the need to tell the world how extremely well this is executed from a technical perspective”

That perfectly describes how I feel too. The world really should know that this is not just a simple witch picture. It is a witch picture with 42 multiplexed sprites below and above it, producing the colors, highlights, and other details. With C64 Graphics Explorer, you can switch the layers on and off one by one and see how Mermaid put the whole thing together.

As a bonus, I also got one of her early sketches, which I reconstructed in Aseprite so you can see exactly how each character changed.

I still read a lot about the Commodore 64, and I understand more and more about how it works. I learned a lot this time too. I more or less read through Mermaid’s roughly 400-line displayer busy loop several times, stepped through it, and so on.

Back in the day, a friend of mine put Lothar Englisch’s classic book, Advanced Machine Code Programming, into my hands. It has yellowed quite a bit since then, but I love it very much. And the book too.