from
memory
to
output
devices goes by way
of
the
processor.
Some peripheral devices, however, are capable
of
transferring information
to
and
from
memory
much faster
than
the
processor itself can accomplish
the
transfer.
If
any
appreciable
quantity
of
data
must
be transferred
to
or
from
such a device,
then
system throughput will be increased by
CPU
MODULE
1·5
having
the
device accomplish the transfer directly.
The
pro·
cessor
must
temporarily suspend its
operation
during such a
transfer,
to
prevent conflicts
that
would arise
if
processor
and peripheral device
attempted
to
access
memory
simul·
taneously. It
is
for
this reason
that
a hold provision
is
in·
cluded
on
some processors.