25 Oct
2010
25 Oct
'10
4:41 a.m.
From: "Tom Gardner" <thomas.gardner at
sbcglobal.net>
On Fri, 22 Oct 2010 11:03:10 +0200 (CEST) Christian Corti wrote:
In my ICT 1301 manuals it always uses the term Immediate Access Store (IAS) for the core
store, in fact I don't think the word core is used except in the engineers maintenance
manuals. My machine also has three drums for storing overlays and data as well as mag
tape. The drums also have reserved bands (only writable with an engineers assistance)
which hold Initial Orders, the machine's bootstrap, along with three half words which
are directly wired into the machine which on pressing a button are forced into the three
control registers which then load Initial Orders from drum.
P.S. I expect it was an oversight but please don't include the whole digest in your
messages.
Per definition, a magnetic drum is not random
access.
A random access storage is defined by the fact
that addressing
any arbitrary cell needs the same time.
That may be today's definition but if you check the literature of the 50's
and 60's I am sure u will find drums (along with Williams Tubes, etc)
categorized as random access devices. Even the first disk drive was the IBM
RAMAC 350 - as in Random Access Memory! I think IBM invented the term
Direct Access Storage in the 1960s to distinguish devices whose assess time
was short but variable; that is, in between core (random) and tape
(sequential).
So the historical definition may have been . needs essentially the same
time.