Re: First language with conditional assignment?

(snip previously on conditional expression)
(Then our moderator wrote)


> [Test and set was in the S/360 architecture in the early 1960s. Dunno
> if it was on earlier machines or if they just did it implicitly using
> add to memory. -John]


I believe that many of the earlier core memory machines would
do read-modify-write instructions by delaying the write-back
needed for core memory. (Read is destructive, so an ordinary
read requires a write back.) That would make it impossible
for any other access, even DMA based I/O, to change memory.
(I believe that is how it is done on the PDP-10.)


Also, with S/360 being the first "architecture," designed to
be implemented in technologies, it may have been time to
consider interlocked update separate from the underlying hardware.


-- glen
[Yup, that's what I meant by doing it implicitly. -John]

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