Forth compiler and interpreter

Implemented commands:

• .S - print stack
• Arithmetic operators ( + - * /, = < )
• Logical operators (and, not)
• rot (a b c --> b c a)
• swap (a b --> b a)
• dup (a --> a a)
• drop (a --> )
• . ( a -- ) pop number from stack and print it
• Input/Output
  • key ( -- c) – read one symbol from stdin
  • emit ( c -- ) – write one symbol to stdout.
  • number ( -- n ) – read signed number from stdin
• Memory Commands:
  • mem - load on the stack a constant - the address of the start of the user memory.
  • ! (data address -- ) – writes data to address;
  • @ (address -- value) – reads the contents of memory at address;