SABRAG, A Time-Sharing Low-Cost Computer

The serial SABRAC computer designed and built
in the Scientific Department of the Israel defense 
Ministry has a 5000-location magnetic drum, main store.
 To avoid a need to resort to optimum programming 
techniques and to increase its overall efficiency the
computer has also been given a 224-word ferrite 
core store from which the program is obeyed.  Transfers
between the core and drum stores and to and from 
the twin paper-tape input and output channels are all
available autonomously (concurrently, time-shared). 
 Multiplication and division orders are also autonomous,
so that the machine may be executing up to three 
orders simultaneously.  All functions naturally are interlocked.
 A number of other advanced orders and 
facilities are also incorporatedn particular, an
"Execute" order permits a temporary jump for up 
to four orders and a second modifier register permits double
modification in general and relative addressing 
of subroutines in particular.  Thus the overall effective
speed of the machine is muchhigher than its 
basic specification would lead one to expect and its
design indicates one way in which the concepts of 
time sharing may be incorporated in "low-cost" computers.

CACM August, 1963

Lehman, M.
Netter, Z.
Eshed, R.

CA630802 JB March 13, 1978  8:54 PM

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