On 9 Feb 2010 at 20:55, Tony Duell wrote:
What about a Turing machine. I would claim that has no
jump
instruciton. And of coruse (apart from the infinite memory), it's
fairly easy to build one in hardware.
Or Dataflow machines, for that matter. Would you count SKIP
instructions as GOTO? There has been more than one machine with
instruction execution depending on the setting of a condition code,
so that whole sequences could be skipped without a GOTO per se.
There's no real reason that a machine even needs to have every
location uniquely tagged by an address for that matter. Turing
machines are again a good example.
I could conceive of a machine with a WHILE-DO instruction pair, the
pairs obeying nesting rules.
Early paper-tape driven machines simply looped the tape to perform an
iterative instruction sequence.
--Chuck