FRONT-END
COMPUTER
The
CRAY-!
computer system
may
be
equipped with
one
or
more
front-end
computer systems
that
provide input data to the
CRAY-!
computer system
and
receive output
from
the
CRAY-!
to
be
distributed
to a
variety
of
slow-speed peripheral equipments. A front-end computer system
is
a
self-
contained system
that
executes under the control of
its
own
operating
system.
Peripheral equipment attached to the front-end computer will
vary depending
on
the
use
to
which
the system
is
put.
A front-end computer
may
service the
CRAY-!
in the following
ways:
•
As
a local operator
station
•
As
a local batch entry
station
•
As
a data concentrator
for
multiplexing several other
stations
into
a
single
CRAY-!
channel
•
As
a remote batch entry
station
Detailed information about the front-end system
is
presented in
separate
publications.
EXTERNAL
INTERFACE
The
CRAY-!
may
be
interfaced
to front-end systems through special
interface
controllers
that
compensate
for
differences
in channel widths,
machine
word
sizes,
electrical
logic
levels,
and
control protocols.
An
interface
is
a
Cray
Research product
and
is
contained in a small
air-cooled
stand-alone
cabinet located near the front-end computer system. A primary goal of the
interface
is
to
maximize
the
utility
of
the front-end channel connected
to the
CRAY-!.
Such
a channel
is
generally slower than
CRAY-!
channels.
The
CRAY-!
may
be
separ~ted
from
the
interface
cabinet
by
up
to
320
ft
of
cable with
no
degradation to
its
effective
transfer
rate.
t1aximum
separation
of
the
interface
cabinet
from
the host processor
is
determined
by
the channel
characteristics
of
the front-end machine.
If
site
condi-
tions
require
that
the interconnected systems
be
physically located a
considerable distance
apart,
the
effective
transmission
rate
may
be
degraded.
2240004
2-7
E
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