Apple ][ Hi-res Myst Proof of Concept

If you're looking for a fully playable Myst for the Apple II+, check out the Lo-res version I made

This page is talking about some proof of concept work done on an AGI-like interpreter I made checking for the feasability of a hi-res MYST with graphics similar to "The Wizard and the Princess".


I was prepping for a Mysterium talk and got to thinking about the eternal question people ask, "why not hi-res". Higher resolution graphics take up a lot more space, but you can use tricks like they did back in the 1980s to essentially make simple vector-based graphics. These are slow and often cartoony looking, but can be a good compromise between lo-res graphics and super-detailed bitmaps.

I did a silly proof of concept in 280 bytes of Applesoft BASIC on the Apple II twitter bot and enough people liked it that I decided to put together a small graphics lib.

As you'll note, I've only implemented a few of the scenes. It's a lot of work, and to do a full game you need 800+! Also for proper gameplay you'd want a hi-res sprite library and a few other things that are tricky in hi-res on the Apple II which has a famously obtuse graphics subsystem (a lot of the complexities can probably be placed on Woz's amazing hardware optimizations to save gates, but you have to make up for it in software).

Legal Note

This product contains trademarks and/or copyrighted works of Cyan. All rights reserved by Cyan. This product is not official and is not endorsed by Cyan.


The Apple II hi-res graphics are a bit too complex to get into here. Roughly, you get 280x192 graphics with 6 colors. There are complex rules about which colors can go where, and you get NTSC fringing.

My VGI (VMW vector-graphics interpreter) is just a small commandset with up to 16 commands, followed by hard-coded paramaters. You can find some more info on that here: VGI page


The intro proof of concept, an actual capture on an Apple IIe platinum:

The intro with voice-over (recorded in an emulator):

The earlier proof of concept with the sarcastic text-mode interface:


Note: these were captured with the AppleWin emulator.

Also, watch the videos if you can, half the fun is watching them draw.

Graphics Comparison

Below is a brief comparison of your graphics options. For a more thorough comparison check out this page discussing graphics tradeoffs with the lo-res Myst port.

Original Graphic
Handmade Lo-res (40x48 15 colors) Version
Automatic conversion Tool-created Hi-res Image
Handmade Hi-res (280x192 6 colors) VGI Graphics

So could it be done?

So would it be possible to make a game in hires with the same footprint as the lores game? It might be, although losing 8k of RAM for the framebuffer will hurt. Also the VGI decoder is a few K as well, and we'd have to write a sprite library for the pointer, and not sure what to do about animations and such.

But for the clock image:

System Requirements


Disk Images



Development Notes

22 September 2021 -- Version 0.03

It was a pain but in theory Apple IIc should work with the music. You need to have a Mockingboard IIc for this. That's actually a hack, as it disables the $C400 firmware when you access the mockingboard and the IIc firmware is hardcoded to send interrupts to $C400 so that's fun. You are forced to use AUX memory and have to copy the Applesoft ROM in too if you use it.

21 September 2021 -- Version 0.02

Have been working on SSI-263 sound chip support due to the Peasant's Quest demake, and somehow got it into my head to do the Myst intro. It's actually a reasonably small amount of code, might try to add it to the lo-res version. While I was at it I also added a .pt3 file of the Cyan theme.

15 July 2021

Spent a week or so modifying the LORES engine to see if I could make HGR fit. Also involved making a minimalistic hires sprite library to handle the cursor. With the current VGI code it was a bit too big to fit so had to re-arrange the memory map a bit and that took a while to sort out. The engine did get bigger, and the graphics are at least twice as big. But it is a semi-functioning proof of concept now.

21 June 2021

Finally got things posted. Thought I was done but forgot I wanted to do a fireplace scene too.

20 June 2021

Wrote filled circle code. Did not write generic triangle routine, even though it would be useful. It's actually hard to write an 8-bit generic triangles. You can modify the Bresenham line drawing, but even that's hard to do in 8-bits because it uses signed numbers and you quickly run out of room.

19 June 2021

The initial box drawing routine using the Applesoft HGR ROM routines is too slow. Mostly because it has no dedicated horizontal line drawing code so it is doing slow address calculation and drawing point-at-a-time.

Writing a fast horizontal line myself turned out to be a huge undertaking and my code is still full of off-by-one errors. While it's fun to curse Woz here, most of my problem was normal stuff like edge cases when the line doesn't start cleanly at byte boundaries (you'd have those issues on any platform). The weird Apple II address stuff can mostly be hidden with some lookup tables (even the weird divide-by-7 stuff).

16 June 2021

Posted an Apple II Basic bot initial implementation which ended up being way more popular than I expected. Since this is vaguely related to a talk I'm giving next month I decided to see how quickly I could put together a "real" vector interpreted scene.

Lo-res Fully Playable Apple II Myst
Other Apple II Demakes
Other VMW Software Demos
Other Apple2 Projects
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