Elliott 503 User manual

DIGITAL COMPUTER
FOR SCIENCE AND INDUSTRY

ELLIOTT
503
ULTRA HIGH SPEED DIGITAL
COMPUTER
FOR SCIENCE AND INDUSTRY
Elliott Brothers have developed the 503 to meet
the demandfor computersoperating at much higher
speeds
than
hitherto without a corresponding in-
crease
in
cost. This computer
will
revolutionise the
economicsof computer usage in several ways
(i) it will handle problems which were formerly
more cheaply solved by manual methods.
(ii)
it
will
provide computingfacilitiesfor organi-
sations with a largenumber of individualusers. Due
to thehigh speed ofthe computer, and thesimplified
programming and operating methods being de-
veloped, owners of 503 can
run
as many as zoo
different programmes each day.
(iii)
it
will
tackle the most complex problems
arising in science and industry, formerlybeyond the
scope of small or medium-sized computers.
As
an
illustration of the advance on currently
available computers which the 503 represents, it is
interestingto compareit
with
the 803. TheNational-
Elliott 803
is
a small general purpose transistorised
computer which
is
the most popular European
zomputer ever produced. Yet the 503 is about one
hundred times faster than
this
machine and costs
less
than
twice as much!
The 503 is a general purpose computer of great
speed and flexibility, intended mainly for the solu-
tion of technical problems arising in science and
industry. It is essentially
straightforward
in design,
but so exceptionally fast that high problem-solving
speeds are obtained.
The computerincorporates many features unique
among medium-sized
data
processing systems
*
~oo,ooo
arithmetic operationsper second.
*
Large magnetic core store.
*
Time-sharing ofperipheral data-transfers.
*
Fixed andjoatingpoint arithmetic.
*
Direct connection
of
high-speed input and output
equipment.
*
Compatibility with well-known
803
computer.
*
Auxiliary magnetic core storage
of
almost unlimited
capacity.
*
ALGOLAutomatic Programming System.

Basic
Compute
The basic 503 forms a powerful and complete
computing system in its own right; it has amagnetic
core store of 8192 words capacity
with
a cycle-time
of 3.5 microseconds. Each word in the store may be
regarded as equivalent to
(a) a fixed point number of 39 binary digits,
equivalent to
11
decimal digits
(b) a floating-point number using nine binary
digits
for the exponent and 30 for the mantissa,
corresponding to a precision of nine decimal digits
(c) Five alphanumeric characters, or
(d) Two single-address instructions.
Input and output for the basic computer is on
punched paper tape, read at
1000
characters per
second and punched at one hundred characters per
second. There are two tape readers and two tape
punches. Eight-channel paper tape is normally used
on the 503, but the equipment can also handle five-
channel paper tape.
The computer
is
controlled from an electric type-
writer which is used for direct input and output.
The basic pulse rate of the 503 is
6.7
megacycles
per second.
The computercontains a parallelbinary arithmetic
unit, and
is
capable of carrying out 100,000 opera-
tions every second.
Typical operation times,inclusiveof store access,
are
as
follows
Fixed-point addition
7
microseconds
Floating-point addition average
20
microseconds
Transfer control
5
microseconds
Fixed-point multiplication
38
to
57
microseconds
Floating-point multiplication
38
to
51
microseconds
Fixed-point division
8
I
microseconds
Floating-point division
7
I
microseconds
The time for the inner loop of matrix multiplica-
tion routine is
126
microseconds, so that two 50 by
50
matricescan be multiplied together
in
16
seconds.
The timerequired to sort ~o,oooitemsof
10
words
each on a 503 with four magnetic tape decks is
estimated at
4
minutes.
Information may be transferred directly between
peripheraldevicesand any block ofconsecutiveloca-
tions in the
main
store of the computer. Once the
transferhas been starteditproceeds under the control
of the Peripheral Control Unit whilst the computer
continues
with
its programme. "Tagw bits
associated with each word in the store of the
computer are used to ensure that the computer
cannot refer to the block of store involved
in
a
transfer untilthenew information has arrived,orthe
old information has been used. However, the com-
puter can refer to the earlier locations of the block
whilst the later locations are still involved
in
the
transfer. These arrangementsare entirely automatic
and need not concernthe programmerwhen writing
his programme.

The following peripheral devices are currently
being offered on the 503
:
Backing magnetic core store in units
of
16,384
words.
Magnetic Film Units (maximum eight).
Magnetic Tape Units (maximum sixteen).
High Speed Line Printer.
Punched Card Reader.
Punched CardPunch.
An
interrupt system is provided in the computer.
Oninterrupt the contents of
all
the special registers
are stored away and the computer transfers control
to another programme. This facility
is
used to deal
with programme and other error conditions such as
floating-point overflow,and to controlthe computer
from the typewriter keyboard. It may also be used,
in conjunction with standard programmes provided
by Elliott Brothers, to enable information to be
transferred between one peripheral device and
another simultaneously with the operation of
an
independent programme. In this way the computer
may be translating an autocode programme whilst
the results of the previousjob are being printed on
the heprinter from magnetic tape.
The 503 computer is designed in such a way as
to achieve extremely high reliability. The smaller
503 systems are run without a resident engineer and
Elliotts provide a comprehensive maintenance ser-
vice.
All
the circuits of the 503 are fdy transis-
torised, and the store
is
a ferrite core matrix, so that
there are no mechanical moving parts other than
input and output devices. Experience gained in the
803 and
in
military
computing systems has enabled
Elliotts to design acomputeras reliableas the simpler
and slower 803.
A
parity check bit is used with everyword in both
the main and backing core stores. Extensive checks
are included on the correct fwlctioning of
all
peri-
pheral devices.
A
parity check is used
with
every
character read or punched on paper tape.
An
auto-
matic error interrupt occurs on the detection of
errors caused by malfunctioningof equipmentorby
certain faults in programming.
The
503
is entirely compatible with the well-
known National-Elliott 803 computer: the word
length and instruction code of the two machines
is
the same.
This
compatibility has
the
following advantages:
(a) The extensive library of programmes already
developed for the
803
is immediately available
for
the
faster machine
(b) Potential
503
users may test their programmes
immediately on the
803
(c)
803
users may exchange their computerfbr a
503
if
theformer machine becomes overloaded without having
to reprogramme their work-a task which would prove
extremelyformiible
(d)
A
central research establishment may install a
503
computer with
803
computers at each
of
its out-stations.
Users ofthe
803's
may run their largerprobletns on
503
after testing them on their own machine.

-
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-
-
---
The basic code of the computer
is
a single address
system
with
one (double length) accumulator and
two instructions per word. There are 64 different
functionsincludingadd-into-store and similar opera-
tions. Each of the
8192
locations of the
main
store
may
be used
as
an index register, thus greatly
simpQing the programming of complex problems.
Theprogrammingsystemsin use on the 803 com-
puter, including the Mark 3 Autocode and the
Matrix Interpretive Scheme,
will
be immediately
availableon the 503.
A
symbolicassemblyprogrammeformachine code
programmers, including facilities for calling
in
sub-
routines by name, is being developed, and
will
be
availablewith the first 503 computers.
Work is well advanced on
an
ALGOL automatic
programming system for 503.
ALGOL
"statements" are written
in
anaturalway
and are very easy to understand.
Examples:
acceleration:=a-32.18xsin
(theta+l);
if a=b and xcepsilon then
y:=(l
-exp (x)
)/x
-
else
y
:=
-1
;
for i:=l step
1
until
N
do sum:=sum+A [i];
ALGOL 60
is
aprogramming languagedeveloped
by an international committee of experts
in
Auto-
matic Programming, and it has been designed not
odyto
simplify
theprogrammingof extremelycom-
plex problems, but also to make the programming
of every-day problems as easy as possible for the
occasional user.
Since the publication of the ALGOL report, a
large number of programmes written in ALGOL by
leading specialistsin the field of computing methods
have appeared
in
mathematical and computing
journals. The Elliott ALGOL translator
will
make
such programmes available to
all
users of the Elliott
503 and 803 computers. It
will
also enable a 503
installation to drawitsstaff from the wideningbody
of programmerswho arefamiliar
with
ALGOL, and
who have developed
an
appreciation for its great
power and simplicity.
Other Computers
by
Elliott Brothers
National-Elliott
803
Small GeneralPurpose Computer
Elliott
502
Real TimeData Processing System

A
member of the Elliott-Automation Group.
Pioneers of the first decade-now leaders of the second decade
Elevenyears' experience
in
the design andapplica-
tion of automaticdigital computers places Elliott
in
aleadingpositionamongEuropeancomputermanu-
facturers
with
more than
150
sales to
date.
From the
first experimental trials recording and analysis
machine
in
1950 to the revolutionary 503 of 1961,
Elliott have been proud to maintain a distinguished
record of significant achievement.
Copyright reserved
ELLIOTT COMPUTING DIVISION
Borehamwood, Heafordshire, 'England. ELStree 2040.
The information given
in
this
leaflet
is
subject to
CP
204
alteration
as
additions and improvements to
the
January
1962
equipment described
are
made.
Printed
by
Cresta
Pra
Ltd.,
Watford.
Hem.