intro to uxn programming workshop

online workshop to learn the basics of uxn programming.

in order to dig deeper, you can get and read our introduction to uxn programming book!

alternatively, you can check out our uxn tutorial online.

at babycastles

Video recording: Babycastles Academy: Intro to Uxn (

Video recording: Babycastles Academy: Intro to Uxn (yt)

Video recording: Babycastles Academy: Intro to Uxn (magnet link)

event info:

Babycastles Academy: Intro to Uxn Programming

sunday, november 21, 12021, at 3pm UTC-5 (EST)


Have you wondered how computers function under layers of abstraction? Are you curious about learning about assembly languages? Would you like to try fun challenges, while getting to know a permacomputing platform? Join us in learning about Uxn!

Uxn is a portable 8-bit virtual computer inspired by forth-machines, capable of running simple tools and games, and programmable in its own unique assembly language called Uxntal.

Uxn is at the core of Varvara computer, a platform for running small audio/visual applications. Varvara has been ported already to several years old and modern computing platforms, like the Gameboy Advance, Nintendo DS, the Playdate, and more.

In this workshop we'll introduce the basic concepts to start programming this computer: its architecture, the programming paradigms of Uxntal, and some low-level aspects that will allow us to create a simple drawing tool!

Pre-requisites: This workshop is best for those with some previous programming experience. However, no previous experience with assembly or low-level computing is needed.

We will use the learn-uxn website by metasyn, that requires a web browser with javascript enabled:



1) uxn, varvara, and its architecture

uxn documentation

varvara documentation

Unknown Fields Division - Summer 2014 China Cargo ship expedition

Rare Earthenware - Unknown Fields

2) uxntal basics

3) drawing into the screen


4) sprite drawing

100R - nasu spritesheet editor

5) interactivity loop

6) conditional behavior

7) outro



links and resources

for the workshop

learn-uxn by metasyn

uxn technical documentation

varvara documentation

decimal to hexadecimal converter

100R - nasu spritesheet editor

uxn source code


and more

uxn tutorial

the uxntal opcode manual

uxntal cheatsheet

uxn repository

llllllll forum

awesome uxn: awesome things from the community

100R - uxn

#uxn in merveilles

example program

( simple drawing tool )

( devices )
|00 @System  [ &vector $2 &pad $6  &r $2 &g $2 &b $2 ]
|20 @Screen  [ &vector $2 &width $2 &height $2 &pad  $2 &x $2 &y $2 &addr $2 &pixel $1 &sprite $1 ]
|90 @Mouse [ &vector $2 &x $2 &y $2 &state $1 &wheel $1 ]

( init )
    ( set system colors )
    #0a6f .System/r DEO2
    #05cf .System/g DEO2
    #0caf .System/b DEO2

    ( configure screen device )
    ;on-frame .Screen/vector DEO2
    ;brush .Screen/addr DEO2

    ( read mouse coordinates )
    ( and use as screen coordinates )
    .Mouse/x DEI2 .Screen/x DEO2
    .Mouse/y DEI2 .Screen/y DEO2

    ( read mouse state and compare for left click )
    .Mouse/state DEI
    #01 EQU ,&draw JCN ( jump when mouse is pressed )

    &draw ( draw sprite: 4-fg, 5-color1 and alpha )
    #45 .Screen/sprite DEO

( sprite data )
@brush 3e7e ffff ffff 7e3c


if you enjoyed this workshop and found it helpful, consider giving us your support :)

compudanzas on patreon

compudanzas on ko-fi

incoming links