padamtoos
2 when a subroutine in the
are baded onto the stacks and SCAL
a executed:
a) Executed
b) invoked
c
)
Ended
d) started
Answers
Step-by-step explanation:
Early history
1842 - Ada Augusta King, Countess of Lovelace - described the idea of a set of reusable instruction for the Analytic Engine
1946 - Turing's ACE
(from Bill Findlay) "Turing wrote a design study for the ACE in the late 1940s that envisaged a stack of return addresses, partly managed by software, and facilitated by the equivalent of a macro-assembler! Some of his ideas were later incorporated in the pilot ACE (at NPL) and the commercially-produced DEUCE. ... It is a remarkable document, discussing everything from the programming system to whether the delay lines should be filled with alcohol or mercury."
A.M. Turing, "Proposals for the development in the Mathematics Division of an Automatic Computing Engine (ACE)." Report E882, Executive Committee, NPL February 1946. Reprinted April 1972 as NPL Report Com. Sci 57.
(I believe this is either a draft of the paper or is the cited paper itself. It discusses performing subsidiary operations that are invoked by BURY instructions and returning control by UNBURY instructions, along with a stack (LIFO) store of instruction addresses in main memory and a stack pointer in temporary storage [i.e., "TS 31"].)
We also wish to be able to arrange for the splitting up of
operations into subsidiary operations. This should be done in
such a way that once we have written down how an operation is
done we can use it as a subsidiary to any other operation.
...
When we wish to start on a subsidiary operation we need only
make a note of where we left off the major operation and then
apply the first instruction of the subsidiary. When the subsidiary
is over we look up the note and continue with the major operation.
Each subsidiary operation can end with instructions for this
recovery of the note. How is the burying and disinterring of the
note to be done? There are of course many ways. One is to keep a
list of these notes in one or more standard size delay lines (1024),
with the most recent last. The position of the most recent of these
will be kept in a fixed TS, and this reference will be modified
every time a subsidiary is started or finished. The burying and
disinterring processes are fairly elaborate, but there is
fortunately no need to repeat the instructions involved, each time,
the burying being done through a standard instruction table BURY,
and the disinterring by the table UNBURY.