$!

$! is a minimalist esoteric programming language created by User:TheCanon2.

Commands

$! has a single 8-bit cell, xxxxxxxx. $! has 2 commands.

Command	Action
$	Shift 1 bit to the left
!	Flip the rightmost bit.

The accumulator is printed as a number at the end of each line.

Examples

Hello, World!

!$$$!$$$
$!$!$$$!$$!
$!$$!$!$$

!$!$!$!
$$$!$$!$!$$
$!$$$$$
!$$!$$!$!$!
!$!$!$!$!
!$$!$
!$$!$!$$
$!$$
$$$!

This prints the ASCII values of the characters in 'Hello, World!' since $! has no character output.

XKCD Random Number

!$$

Implementations

The following Python script is an interpreter.

data = 0
code = [""]
while code[len(code)-1] != "eof":
    code.append(input('> '))
code.pop(0)
code.pop()
code.append("")
code = '\n'.join(code)
for inst in range(0, len(code)):
    if code[inst] == "$":
        data *= 2
    elif code[inst] == "!":
        if data % 2 == 1:
            data -= 1
        else: data += 1
    elif code[inst] == "\n":
        print(data)
    data = data % 256

This interpreter uses the symbol eof to mark the end of the program.