DMS

A command consists of an expression, with any number of operators applied to it, for example _<@!-'A

Commands are executed in sequence, looping to the top after the last command has run.

The resulting value from each command is added to the current cell.

Outputting 0 as a char terminates the program.

You can use # to comment out the rest of a line.

There is also a more exact specification here

Expressions

Symbol	Name	Returns
Any sequence of digits 0-9	NUMBER	The base-10 interpretation of those digits as an integer i.e. 123 returns 123
' followed by any character C	CHAR	The UTF-16 value of the character C as an int, i.e 'a returns 97
.	CELL	Value stored in the current cell
%	COMMAND_POINTER	The command pointer
[	CELL_POSITION_X	The X coordinate of the cell pointer
]	CELL_POSITION_Y	The Y coordinate of the cell pointer

Operators

Let I denote the input to each operator for the descriptions of effects and return values.

Symbol	Name	Effect	Returns	Notes
-	NEGATE	No effect on state	-I	-123 is - applied to 123, returning -123
+	SIGN	No effect on state	The sign of I -- 1 if I is positive, -1 if I is negative, 0 otherwise
!	COMPLEMENT	No effect on state	1 - I	!1 returns 0, !0 returns 1, !6 returns -5
?	CONDITION	No effect on state	I if the current cell value is positive. 0 otherwise
_	DISCARD	No effect on state	Always returns 0, ignoring its input	Useful for creating a command that updates the state of the machine but doesn't write anything to the current cell.
@	CHAR_OUTPUT	Writes I, interpreted as a UTF-8 character, to standard output. If I is 0, terminates the program instead	I (unchanged)	Outputting the NUL char (0) is the only way to terminate a DMS program
*	INT_OUTPUT	Writes I, formatted as a base-10 integer, to standard output.	I (unchanged)
:	JUMP	Increases the command pointer by I	I (unchanged)	Jumping past the last command or before the first causes the command pointer to wrap around. Jumping by -1 (:-1) will result in the same command being executed in a loop.
<	LEFT	Decreases cell pointer's X value by I	I (unchanged)	Cell positions wrap at the edges of the tape
>	RIGHT	Increases cell pointer's X value by I	I (unchanged)	Cell positions wrap at the edges of the tape
^	UP	Decreases cell pointer's Y value by I	I (unchanged)	Cell positions wrap at the edges of the tape
v	DOWN	Increases cell pointer's Y value by I	I (unchanged)	Cell positions wrap at the edges of the tape
/	PUSH	Pushes I to the top of the stack	The new stack size
|	READ	No effect on state	The value on the stack I positions deep. If the stack is empty, returns the current cell value instead	|0 returns the topmost stack element. Stack positions wrap around, so |-1 returns the bottom element of the stack.
\	POP	Removes the value on the stack I positions deep. If the stack is empty, there is no effect.	The removed value. If the stack is empty, returns the current cell value instead	\0 removes and returns the topmost stack element. Stack positions wrap around, so \-1 removes and returns the bottom element of the stack.
;	DEBUG	Writes debug information about the current state to standard output. No other effect on state	I (unchanged)