Many operations
are
performed in
floating-point
format
and on strings of
characters.
Other
typical
characteristics
include decimal arithmetic operations, binary to decimal
number conversion (for printing or display), and high sys-
tem i
nput/
output transfer rates.
General-purpose
features
are
described in
the
following
paragraphs.
Floating-Point
Hardware. Both short (32-bit) and long
(64-bit) formats
are
available
in
the
floating-point
in-
structions. Under program
control,
the
user may
select
optional
zero
checking,
normalization,
floating-point
rounding and
significance
checking.
Significance
check-
ing permits use of short
floating-point
format for high
pro-
cessing speed and storage economy and of long
floating-
point format when loss of
significance
is
detected.
Decimal Arithmetic Hardware. Decimal arithmetic
instruc-
tions
operate
on
up
to
31
digits plus sign. This instruction
set includes
pack/unpack
instructions for converting to/from
the
packed
format of two digits per byte, and a
generalized
edit
instruction for
zero
suppression,
check
protection,
and
formatting, with
punctuation
to display or print
it.
Indirect
Addressing.
Indirect
addressing faci
litates
table
linkages and permits keeping
data
sections of a program
separate
from procedure sections for
ease
of maintenance.
Displacement Indexing. Indexing by means of a IIfloating
li
displacement permits accessing a desired
unit
of
data
with-
out considering its
size.
The index registers
automatically
align
themselves appropriately; thus,
the
same index
reg-
ister may be used on arrays with different
data
sizes. For
example,
in a matrix
multiplication
of any array of full
word,
single-precision,
fixed-point
numbers, the results
may be stored in a second array as
double-precision
num-
bers, using
the
same index
quantity
for both arrays.
If
an
index register contains
the
value
of
k,
then
the
user always
accesses
the
kth
element,
whether
it
is
a byte, halfword,
word, or doubleword. Incrementing by various
quantities
according
ro daro size is nor required; instead,
increment-
ing
is
always by units in a continuous array
table
regardless
of the size of
data
element used.
Instruction Set. More than 100 major instructions permit
short, highly optimized programs to be written. These
are
rapidly assembled and minimize both program space and
execution
time.
Translate Instruction. The Translate instruction permits
rapid translation
between
any
two
8-bit
codes; thus,
data
from a
variety
of input sources
can
be handled and
re-
converted
easi iy for output.
Conversion Instructions.
Two
generalized
conversion
in-
structions provide for bidirectional conversions between
internal binary and any other weighted number system,
including
BCD.
4 Time-Sharing Features
Call
Instructions. These four instructions permit handling
up
to
64 user-defined subroutines, as if they were
built-in
machine instructions.
Call
instructions also
gain
access
to
specified operating system services without requiring its
i nterventi on.
Interpret Instruction. The Interpret instruction simplifies
and
speeds
interpretive
operations such as
compilation,
thus
reducing space
and
time requirements for compilers and
other
interpretive
systems.
Four-Bit Condition
Code.
Checking results is simplified by
automatically
providing information
on
almost every instruc-
tion
execution,
including indicators for overflow,
under-
flow,
zero,
minus, and plus, as
appropriate,
without
requiring an
extra
instruction
execution.
Direct
Input/Output
(DIO). Direct
input/output
faci
li-
tates
in-line
program control of asynchronous or
special-
purpose devices. This
feature
permits information to be
transmitted
directly
to or from general-purpose registers.
Multi lexor
Input/Out
ut Processor (MIOP).
Once
initia-
lized,
I 0 processors
operate
independently of
the
basic
processor, freeing
it
to provide faster response to system
needs.
An
MIOP requires minimal
interaction
with
the
basic processor.
I/O
command doublewords permit both
command chaining
and
data
chaining
without intervening
basic processor
control.
I/o
equipment speeds range from
slow rates involving human
interaction
(teletypewriter,
for
example)
to
transfer
rates
of
rotating
memory
devices
of
over
750,000
bytes per second. Peripheral controllers
at-
tached
to
an
MIOP may be operated simultaneously.
Rotating Memory Processor
(RMP).
An
RMP
supports up to
15
disk drives, one
at
a time, permitting large
capacity,
high transfer
rate
files. Dual access (between 2
RMPs)
op-
tion is
available.
TIME
-SHARING
FEATURES
Ti me-shari
ng
is the abi
Ii
ty of a system to share its tota I
resources among many users
at
the same time. Each user
may be performing a different task, requiring a different
share of
the
available
resources. Some users may be
on-
line in
an
interactive,
IIconversational
li
mode with
the
basic processor
while
other users may be entering work to
be processed
that
requires only final output.
Time-sharing features
are
described in
the
following
paragraphs.
Rapid Context Saving. When changing from one user
to
another,
the operating environment
can
be switched quickly
and easily.
Stack-manipulating
instructions permit storing
in a push-down stack of 1 to
16
general-purpose registers by
a single instruction.
Stack status is updated
automatically
and information in
the
stack
can
be retrieved when needed
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