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Dathanna (Irish for "colors") is an esoteric programming language for Apple II emulators.


Most classic computers from the 1980s have emulators so old code can run on modern hardware. Many of these emulators support running as quickly as possible, often several orders of magnitude faster than the original machine. Dathanna takes advantage of this speed to make tolerable an implementation that would otherwise be far too slow on the original hardware.

Dathanna is featured in Chapter 16 of the book Strange Code: Esoteric Languages That Make Programming Fun Again (No Starch Press, 2022).

Language Description

Dathanna programs are constructed from pairs of colored blocks stacked one on top of the other. The top color specifies the command and the bottom a modifier for that command. Programs are arranged on the screen and execute from left to right, top to bottom.

Arithmetic operations use a stack with colors doing double-duty as commands or numbers. The stack supports floating-point numbers but only the integers 0 through 15 can be pushed on the stack directly.

Dathanna colors and numeric values
Dathanna colors and numeric values


Commands are a top color with the lower color a modifier.

Value Color Top Bottom
0 black HALT Terminate program (any)
1 magenta PUSH push number to top-of-stack (TOS) (any)
2 dark blue INPUT number to TOS (orange)
character to TOS (light green)
3 purple COMPARE < (gray 1)
<= (medium blue)
> (light blue)
>= (brown)
= (orange)
<> (gray 2)
(r c -- ) branch (purple)
(r c f -- ) if (aquamarine)
4 gray 1 STACK dup (magenta)
drop (dark blue)
swap (purple)
rot (gray 1)
over (medium blue)
nip (light blue)
7 light blue PRINT TOS as number (orange)
TOS as character (light green)
9 orange MATH + (black)
- (magenta)
* (dark blue)
/ (purple)
ˆ (dark green)
sqrt (gray 1)
sin (medium blue)
cos (light blue)
tan (brown)
abs (orange)
exp (gray 2)
log (pink)
int (light green)
rnd (yellow)
atn (aquamarine)
mod (white)
12 light green STORE ( v idx -- ) (any)
13 yellow FETCH ( idx -- v) (any)
14 aquamarine PUTV TOS to var number (any)
15 white GETV var number to TOS (any)


Hello, world!

Dathanna world.png

Random Pi

Dathanna pi.png

Gnome Sort

Dathanna gnome.png

Computational class

Like Befunge-93, Dathanna programs are restricted to one screen. Therefore, Dathanna is not Turing complete.