BackStart

BackStart is a version of the Minsky machine with a single counter.

Commands

Command	Operation
i x	Add x to the counter.
d x	Decrement the counter x times if it is not zero; if it is zero return to the start of the program. If the counter is lower than zero following the decrementing, an error is signaled.
b	Return to the start of the program.
o x	Output the number x if does not equal zero. If x is zero, output the counter instead.

translation to UBLANG

BackStart	UBLANG
i x	+ x times
d x	- x times
b	/
o 0	.
o x	* x times, ; and / x times

Examples

Hello World

The following program prints “Hello, world!”:

o 72
o 101
o 108
o 108
o 111
o 44
o 32
o 119
o 111
o 114
o 108
o 100
o 33

Infinite Counter

This program prints the infinite sequence of integers starting from inclusive one (1):

i 1
o 0
b

Interpreter

• Common Lisp implementation of the BackStart programming language.