Uxn Sticker picture
15C06 — Uxn Sticker

Uxn is a stack-machine with 32 instructions.

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

It was designed with an implementation-first mindset with the goal of targeting salvaged computers, the distribution of Uxn projects is akin to sharing game roms for any classic console emulator.


StacksWorking StackPointer1 byte
Data256 bytes
Return StackPointer1 byte
Data256 bytes
MemoryRAMPointer1 short

The CPU can tunnel through 128 subroutines and find its way back with its return stack. The CPU can connect to up to 16 devices at once, devices can be peripherals such as screens and controllers, or even an other Uxn CPU.

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Tal is the programming language for the Uxn stack-machine.

The programming language for creating Uxn-compatible applications is called Uxntal or simply Tal, it is a unique flavor of assembly designed for this unique stack-machine. The program that transforms Tal files, into Uxn-compatible roms, is the Uxn Assembler.

Stack machine programming might look at bit odd, as it uses a postfix notation, which means that operators are always found at the end of an operation. For instance, one would write 3 4 + instead of 3 + 4. The expression written (5 + 10) * 3 in conventional notation would be written 3 10 5 + * in reverse Polish notation.


Varvara is a clean-slate computing stack based on the Uxn CPU.

The Varvara computer system was designed with a focus on portability, built on top of the 8-bit Uxn stack-machine. It is an ideal platform for running small audio/visual applications. To see a list of compatible software, see roms.

Devices are external systems connected to the Uxn CPU, such as the screen, the mouse, the keyboard, etc. There is a maximum of 16 devices, each device has 16 bytes of I/O memory.

incoming(15): virtual machines varvara macintosh assembly forth devine lu linvega roms tools chr format ufx format snarf dexe nasu noodle left

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