I
Individual elements of a V
register
are designated in
this
manual
by
deci-
mal
numbers
in the range
00
through
63.
These
appear as subscripts to
vector
register
references.
For
example,
V6
29
refers
to element
29
of
vector
register
6.
V
register
reservations
The
term
"reservation" describes the
register
condition
when
a
register
is
in
use
and
therefore not available for
use
as
a
result
or
as
an
operand
register
for another operation.
During
execution
of
a vector
instruction,
reservations are placed
on
the operand V
registers
and
on
the
result
V
register.
These
reservations are placed
on
the
registers
themselves, not
on
individual elements of the V
register.
A reservation for a
result
register
is
lifted
during "chain
slot"
time.
Chain
slot
time
is
the clock period
that
occurs
at
functional
unit
time
plus
two
clock periods.
During
this
clock period, the
result
is
available for
use
as
an
operand in another vector operation.
Chain
slot
time
has
no
effect
on
the reservation placed
on
operand V
registers.
A V
register
may
serve only
one
vector operation
as
the source of
one
or
both operands.
No
reservation
is
placed
on
the
VL
register
during vector processing.
If
a vector
instruction
employs
an
S
register,
no
reservation
is
placed
on
the S
register.
It
may
be
modified in the next
instruction
after
vector
issue without
affecting
the vector operation.
The
length
and
scalar
operand
(if
appropriate)
of
each
vector operation
is
maintained apart
from
the
VL
register.
Vector operations
employing
different
lengths
may
proceed con-
currently;
however,
the vector length should not
be
changed
between
opera-
tions
that
chain because chaining implies operations
of
the
same
length.
The
Ao
and
Ak
registers
in a vector
memory
reference are
treated
in a
similar
fashion.
They
are available for modification immediately
after
use.
The
vector
store
instruction
(177)
is
blocked
from
chain
slot
execution.
The
vector read
instruction
(176)
is
blocked
from
chain
slot
execution
if
the
memory
increment
is
a multiple of eight
on
a 16-bank
machine
or
is
a
multiple of four
on
an
8-bank machine. A vector read cannot chain
if
speed control
is
in
effect.
Speed
control
is
caused
by
bank
cohflictsdue
to the increment,
which
varies
between
8
and
16
bank
machines.
2240004
3-5
E
To Next Page
Loading...