abstract machine

1. language A processor design which is not intended to be

implemented as hardware, but which is the notional executor

of a particular intermediate language (abstract machine

language) used in a compiler or interpreter. An abstract

machine has an instruction set, a register set and a model

of memory. It may provide instructions which are closer to

the language being compiled than any physical computer or it

may be used to make the language implementation easier to

port to other platforms.

A virtual machine is an abstract machine for which an

interpreter exists.

Examples: ABC, Abstract Machine Notation, ALF, CAML,

F-code, FP/M, Hermes, LOWL,

Christmas, SDL, S-K reduction machine, SECD, Tbl,

Tcode, TL0, WAM.

2. theory A procedure for executing a set of instructions in

some formal language, possibly also taking in input data and

producing output. Such abstract machines are not intended to

be constructed as hardware but are used in thought

experiments about computability.

Examples: Finite State Machine, Turing Machine.

(1995-03-13)