B E T A B L O C K E R (C) 2010 Dave Griffiths 
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Betablocker is a 8 bit processor with 256 bytes of memory. It's capable only of playing music, and it's threads of execution (which share the same memory) never crash or cease execution.

You write into memory in order to edit programs literally as they are running.

Instruction Set

Instr Oper Push Pop  Description
----------------------------------------------------------------------------
NOP   0    0    0    Does nothing
ORG   0    0    0    Program start
EQU   0    1    2    Push 1 if top 2 items in stack are equal, otherwise 0
JMP   1    0    0    Sets program counter
JMP   1    0    0    If top is 0, sets program counter
PSHL  1    1    0    Pushes literal to stack
PSH   1    1    0    Pushes value at this address
PSHI  1    1    0    Indirect push address at address
POP   1    0    1    Pop stack to address
POPI  1    0    1    Indrect pop stack to address at address
ADD   0    1    2    Adds top 2 items and pushes result
SUB   0    1    2    Subtracts top 2 items and pushes result
INC   0    1    1    Increments top of stack
DEC   0    1    1    Decrements top of stack
AND   0    1    2    Pushes bitwise AND of top two stack items
OR    0    1    2    Pushes bitwise OR of top two stack items
XOR   0    1    2    Pushes bitwise XOR of top two stack items
NOT   0    1    1    Pushes bitwise NOT of tow stack item
ROR   1    1    1    Bitwise right rotate top of stack 
ROL   1    1    1    Bitwise left rotate top of stack
PIP   1    0    0    Increments addr in-place (push increment pop)
PDP   1    0    0    Decrements addr in-place (push decrement pop)
DUP   0    1    0    Duplicates top of stack
NOTE  0    0    1    Plays current instrument at pitch from top of stack
VOX   0    0    1    Changes current instrument to top of stack