Friden EC-130 User manual

‘ 2 e
Hriden.
Z.
ee
K.
G.
Stoltenberg
bate
August
1,
1965
10
ALL
FRIDEN
OFFICES
SUBJECT COMPUTER PRINTOUT (MDD) for EC-132
HOME OFFICE CORRESPONDENCE
SAN LEANDRO, CALIFORNIA
A SUBSIDIARY OF THE SINGER COMPANY
ACTION:
REASON:
Form 70-1
File
for
future
use
when
EC-132
Calculators
become
available
in
your
area.
Servicing
of
the
EC-132
requires
the
information
in
and
included
with
this
MDD.
Re-schooling
of
personnel
is
not
contemplated
because
knowledge
of
the
EC-130
and
the
EC-132
information
furnished
herewith
should
suffice.
Included
with
the
MDD
is
a
Preliminary
Service
Manual
for the
EC-132.
The
manual
has
been
written
only
to
include
sufficient
information
for
EC-130
trained
personnel
to
adequately
service
the
EC-132.
Also
included
is
a
Logic
Block
Diagram
for
the
EC-132.
Ken Stoltenberg
Technical Publications Supervisor

Hriden, %.
178269394Si2le
00791 35081 1.31
00002! 8631449
goggg04! 551.36
ELECTRONIC CALCULATORS
SERVICE MANUAL
riden, ye
SAN LEANDRO - CALIFORNIA
A SUBSIDIARY OF THE SINGER COMPANY

ELECTRONIC CALCULATOR 132
TEMPORARY SERVICE MANUAL
TABLE OF CONTENTS
FOREWORD
SECTION 1 - GENERAL DESCRIPTION
SIMILARITIES TO THE EC-130
DIFFERENCES FROM THE EC-130
SQUARE ROOT KEY
CLEAR DISPLAY KEY
DECIMAL POINT SWITCH
DECIMAL POINT POSITION
REGISTER 4 DATA RETENTION
ENTRY COUNTER
PILOT LIGHT
SECTION 2 - ANALYSIS OF OPERATION
SQUARE ROOT MATHEMATICS
SQUARE ROOT FLOW CHART
PHASE COUNTER
DECIMAL POINT COUNTER LOGIC
REGISTER EXPANSION
DECIMAL POSITION LOGIC
CLEAR DISPLAY LOGIC
REGISTER 4 RETENTION
ENTRY COUNTER LOGIC
PILOT LIGHT CIRCUIT
SECTION 3 - ADJUSTMENTS
NO ADJUSTMENTS FURNISHED
2-1
2-11
2-17
2-23
2-27
2-29
2-30
2-31
2-33
2-36

ELECTRONIC CALCULATOR 132
TEMPORARY SERVICE MANUAL
FOREWORD
The EC-132 is the basic EC-130 modified for Square Root
Function, Servicing the EC-132 necessitates a thorough
knowledge of the EC-130. Therefore, the EC-132 Service
Manual contains only the correlation of the EC-132 with
the EC-130 and a description and explanation of the cir-
cuits which have been added or redesigned.
Any particular area of the EC~132 which is not covered,
then, indicates that there is no change from the EC-130
and information regarding that area will be found in the
EC-130 section of the Electronic Calculators Service
Manual,

ELECTRONIC CALCULATOR 132
TEMPORARY SERVICE MANUAL
SECTION
1
GENERAL
DESCRIPTION

8-1-65 ELECTRONIC CALCULATOR 132 Section 1
TEMPORARY SERVICE MANUAL Page I
SECTION 1 - GENERAL DESCRIPTION
A. SIMILARITIES TO THE EC-130
In all but a relatively few respects the EC-132 looks exactly like the EC-130. The ex-
ternal differences are: the addition of a Square Root key to the keyboard; the change of
CLEAR ALL key to read CLEAR DISPLAY; the addition of a pilot light located in the lower
right portion of the keyboard mask; the optional addition of an Entry Counter to the right
side of the CRT mask; and a new Decimal Point Position Thumbwheel.
B, DIFFERENCES FROM THE EC-130
The internal differences of the EC-132 and the EC-130 are relatively minor with the
exception of the addition of Square Root Function Logic. All of the logic of the EC-130
has been retained intact with respect to functions other than Square Root with the ex-
ception of Clear All, which is now Clear Display and affects Registers 1 through 4
(R1-R4) only.
1. SQUARE ROOT KEY
Depressing the Square Root key on the keyboard initiates certain machine operations
that result in the square root of the number that is displayed in Rl being extracted and
displayed as an answer in the answer register (R1l).
2. CLEAR DISPLAY KEY
Depressing the CLEAR DISPLAY key on the keyboard results in the numbers in all
display registers (R1, R2, R3, R4) being discarded. This is done by inhibiting the count
in A counter (Increment A) from the delay line circuits. Since only the display registers
are affected, RS, the undisplayed storage register, is not cleared.
3. DECIMAL POINT SWITCH
In the EC-130, the Decimal Point switch was installed in the keyboard assembly. In
the EC-132, the switch has been removed from the keyboard assembly and installed under-
neath the keyboard mask in close proximity to the Decimal Point Position Thumbwheel.
Also, the switch is a completely new design that permits, with associated logic, decimal
point position in any one of the 13 display columns, or operation with no decimal point.
4. DECIMAL POINT POSITION
In the EC-130, the decimal point position was limited to one of five places. In the
EC-132, the decimal point may be positioned in any one of the display columns, or
operations performed with no decimal point. The Decimal Point Position Thumbwheel has
been slightly redesigned to locate these 14 positions (0 and 1-13) and to operate with the
new Decimal Point switch.

Section
1
ELECTRONIC
CALCULATOR
132
8-1-65
Page
2
TEMPORARY
SERVICE
MANUAL
5. REGISTER 4 (R4) DATA RETENTION
In
the
EC~130,
any
operation
involving
a
shift
down
of
data
places
R4
data
in
R3
and
places
zeroes
in
R4,
In
the
EC-132,
an
operation
involving
shift
down
retains
R4
data
in
R4
and
repeats
R4
data
in
R3.
In
effect,
then,
R4
becomes
another
storage
register
for
the
retention
of
data.
However,
in
any
operation
involving
shift
up
R4
data
is
discarded,
as
is
the
case
in
the
EC-130.
6. ENTRY COUNTER
The
Entry
Counter
(optional)
in
the
EC-132
permits
a
total
to
be
kept
of
the
number
of
entries
of
a
group
of
entries
as
they
are
placed
in
the
machine.
The
Entry
Counter
is
a
four-digit
counter
that
is
installed
on
the
right-hand
side
of
the
CRT
display.
A
RESET
button
is
included
to
permit
reset
of
the
counter
to
zero
before
the
initiation
of
a
new
group
of
numbers.
7. PILOT LIGHT
In
the
EC-130
and
EC-132,
dividing
by
zero
keeps
the
machine
in
an
operational
loop
that
keeps
the
Display
blanked.
In
this
condition
there
is
no
Display
indication
that
the
machine
is
on.
If
the
machine
should
be
covered
while
On,
heat
build-up
could
cause
damage
to
semi-conductors
and
to
other
components.
In
the
EC-132,
a
Pilot
Light
is
in-
stalled
at
the
lower,
right-hand
corner
of
the
keyboard
mask
that
indicates
an
On
condition
when
power
is
applied
to
the
machine.

ELECTRONIC CALCULATOR 132
TEMPORARY SERVICE MANUAL
SECTION 2 ANALYSIS of OPERATION

8-1-65 ELECTRONIC CALCULATOR 132 Section 2
TEMPORARY SERVICE MANUAL Page l
SECTION 2 - ANALYSIS OF OPERATION
A. SQUARE ROOT MATHEMATICS
The EC-130 uses a modified 'Sum of the Odd Integers'' method of extracting a square
root, The method usually taught in school is not easily adapted to digital techniques, thus
another system must be used. The sum of the odd integers is but one of many ways of
arriving at a square root.
Odd integers are the whole numbers 1, 3, 5, 7, 9, 11, etc. If such a succession of odd
integers, (odd-order arithmetic progression), are added, each summation will result ina
perfect square. A perfect square is a number whose square root is a whole number. The
following table illustrates this.
1) 1402121
2) 14354 =2?
$y 1a 3-63 9 2 3
4) Lie Se 5 eS 16 Sa?
5) 143454749525 =5°
By adding the next higher odd order integer to each preceding summation, all existing
perfect squares are produced, and none is omitted. Note that the NUMBER of odd order
integers in each summation IS the square root of the sum. In example 5, there are 5 parts
to
the
summation,
and
5
is
the
square
root
of
25.
This
holds
true
for
any
combination
of
successive odd integers.
As another example:
l+34+4 5+ 749411 + 13 =49
1; 2; 3; 4; 5; 6; 7;
2
Therefore, \/ 49 =7
By reversing this procedure, the square root can be extracted. In this case, we
SUBTRACT successive odd integers to arrive at the root, starting at l.
For example:
16 15 12 7
- 1 - 3 - 5 at
15 12 7 0
(1) (2) (3) (4)
Therefore, MG ae

Section 2 ELECTRONIC CALCULATOR 132 8-1-65
Page 2 TEMPORARY SERVICE MANUAL
The
number
of
successful
subtractions
is
the
square
root.
If
a
larger
number
is
used,
more
subtractions
are
necessary.
64 63 60 55 48 39 28 15
oe ee ee es
63 60 55 48 39 28 15 0
(1) (2) (3) (4) (5) (6) (7) (8)
The square root of 64, then, is 8.
This
is
a
satisfactory
method
for
use
with
perfect
squares.
A
slight
change
is
necessary,
however,
to
alter
the
method
for
numbers
that
do
not
have
an
integral
square
root.
Rather
than
count
the
subtractions
to
arrive
at
the
root,
we
can
apply
a
simple
formula.
2
.
In the last example, (,/ 64), note that the last number successfully subtracted is 15.
Adding
1
to
this,
(15
4
1
=
16),
then
dividing
by
2,
(16/2
=8),
gives
the
square
root
in
another way. Expressed as a formula:
=(n+
1)/2,
when(R
}s
the
last
integer
to
be
successfully
subtracted,
(no
over-
draft),
and
is sometimes
called
the
"partial
root!'.
An example will show the complete method developed so far.
100
99
96
91
84
45
64
51
36
19
a
A
A
OR
99 96 91 84 75 64 51 36 19 0
he ee a ea =10
Thus, the square root of 100 is 10.
The method developed to this point is perfectly valid for small numbers, but it is
cumbersome
for
large
numbers.
Since
the
number
of
subtract
cycles
is
equal
to
the
square
root
of
the
number,
an
excessive
length
of
time
is
necessary
to
complete
a
problem
using
large
numbers.
To
avoid
this,
another
change
must
be
made.
Starting at the decimal point, the number is divided into pairs of digits, called couplets.
Beginning
at
the
most
significant
couplet,
the
answer
can
be
derived,
one
digit
being
pro-
duced
for
each
couplet.
However,
the
couplets
must
be
operated
upon
in
a
way
that
is
somewhat different than was done in the previous examples.
If
the
number
that
is
to
have
its
square
root
extracted
is
441,
it
appears
as
04
41
when
divided
into
couplets.
The
root
of
each
couplet
will
become
one
digit
of
the
final
square
root,
which
will
have
2
digits
to
the
left
of
the
decimal
point.
However,
the
root
of
04,
and
the
root
of
41
cannot
be
combined
in
any
way
to
produce
the
root
of
the
original
number.
The
following
example
will
serve
to
illustrate
the
method
used
with
the
couplets.

Balabs:.
ELECTRONIC
CALCULATOR
132
Section
2
TEMPORARY
SERVICE
MANUAL
pages
The
first
step
is
to
operate
upon
the
most
significant
couplet
by
subtracting
successive
odd
integers.
yoo
04 03
> | - 3
“03. «00
Now,
we
do
not
apply
the
formula
in
its
entirity.
A
1
is
added
to
the
3,
but
we
do
not
divide
by
2
yet.
3
+
1
=4,
and
this
is
used
to
begin
operation
on
the
second
couplet,
First,
however,
since
the
partial
root
for the
most
significant
couplet
is
in
the
10's
column
of
the
final
result
it
must
be
altered
slightly
by
multiplying
by
10.
cK
me
Sh
The
second
step
is
to
use
this
result,
(4
x
10
=
40),
add
1,
and
begin
operations
on
the
second couplet.
“ft
41 ¥
g@ L ~41
~ 00
Now we can apply the formula, and (41 + 1)/2 =42/2 =21
Thus,
the
square
root
of
441
is
21.
In
this
example,
there
is
no
remainder,
so
the
problem
is
completed
at
this
point.
A
number
that
results
in
a
remainder
in
the
first
step
is
treated
in
much
the
same
st
ok
obae
manner.
For
example,
let
us
extract
the
square
root
of
841.
ge
\
.
oo
ras
Step
l.
08
41
(couplets)
GX
12°
uo
f
4
“
uy
-01
yo.
fF
vet
07
"e,
iy
mi,
i
mo
wv
Yen
ay
h
07
“ae
04
41e*
icy
Gee
i
hel
04
05
(overdraft)
(restore)
In
this
case,
3
is
the
largest
odd
integer
successfully
subtracted
and
so
becomes
the
partial
root,
Multiplying
by
10
to
adjust
for the
columnar
position,
after
incrementing
by
1,
results
in
(3
+1)
x10
=4
x10
=
40.

Section 2 ELECTRONIC CALCULATOR 132 8-1-65
Page 4 TEMPORARY SERVICE MANUAL
Step 2. The remainder above, (04), combines with the other couplet (04 41). Use
the partial root, (40), again incremented by one as we repeat the odd integer method.
04 41 04 00 03 57 03 12 02 65
-_4i - 43 = 45 0C Te
04 00 03 57 03 12 02 65 02 16 oe
02 16 Ol 65 Ol 12 00 57 BAR Re
- 51 - 53 = 55 OOnS ee
01 65 01 12 00 57 00 00 ie
The last number successfully subtracted is 57. Again applying the formula:
R =(n + 1)/2 = (57 + 1)/2 = 58/2 =29
Thus, the square root of 841 is 29.
The method that has been developed up to this point is easily implemented by typical
digital techniques. For a machine similar to the EC 130, however, it will require too much
time
to
be
a
practical
method.
The
final
step
of
dividing
by
2,
which
can
add
as
much
as
one second to the total time required, is to be avoided if possible. The following procedure
can be used to eliminate this step.
The
previous
examples
used
successive
odd
integers
in
the
subtraction
process,
as
1,
3, 5,
7,
9,
etc.
The
final step
in
the
process
is
the
division
by
2.
The
same end
result
can
be
produced
by
separating
each
of
the
above
subtraction
cycles
into
2
steps.
The
table
below
shows
how
this
can
be
done.
Note
that
for
each
normal
subtract
cycle
there
are
2
subtract
cycles
in
the
modified
system.
The
first
half
of
the
subtract
pair
uses
the
pre-
vious
integer
developed
in
the
prior
step.
(In
the
first
subtract
cycle
this
is
of
course
0.)
The
second
half
of
the
subtract
pair
uses
the
same
integer
with
1
added,
(incremented
by
1).
Thus,
in
the
modified
method,
the
first
subtraction
is
by
zero,
and
the
second
subtraction
is
by
1,
(0
+
1).
The
first
half
of
the
second
pair
subtracts
a
2,
(1
+
1),
and
so
on.
NORMAL METHOD MODIFIED METHOD
Subtract
cycles
Odd
integer
Subtract
cycles
Odd
integer
3
4
5
+
—
+
=
iy
Nw + a
It
Ww
+
OLO NID Up WIN &
e foo)
5th pair

8-1-65 ELECTRONIC CALCULATOR 132
TEMPORARY SERVICE MANUAL
Section 2
Page 5
Since there are twice as many subtract cycles as before, it is not necessary to divide
by 2 at the final step. The last successful subtract IS the root by this method. A complete
example to 4 significant digits in the root is given below to illustrate the way the method
works.
geese 181 in ee eee
Subtract 2 Subtract a9 —(1 moved left one place)
pair (1) pair (1)
Last ye (add 1) eat 1)
successful 00 Remainder 60
subtract f Ol Subtract | 11
(Overdraft) pair (3) Ny
(Restore) +o (aad 1)
Subtract (_— i.
pair (5) \ 25
Last /S —— (add 1)
reccestuh 12 ——Remainder
subtract 13
(Overdraft)
(Restore)
The last successful subtraction yielded the number 13, and the square root of 181 is 13
This decimal amount can be found by continuing the subtractions
plus a decimal amount.
using another couplet (00) and
whatever remainder is left, in this case 12.
To illustrate, using remainder 12:
Remainder Couplet added
1200 (13 moved left one place)
Subtract \ 130
pair (1) 1070
Tae
131
——-(add
1)
939
Ste cage 131
pair (3) 808
676
Subtract a= 132
pair (5) 544
ee 133 —— (add 1)
411
Subtract |S 1333
pair (7) 278
Last successful
subtract (pair)
> 134 —(add 1)
144 —— Remainder
134
10
135
(Overdraft)
(Restore)

Section
2
ELECTRONIC
CALCULATOR
132
8-1-65
Page
6
TEMPORARY
SERVICE
MANUAL
The
last
successful
subtraction
yielded
the
number
134,
which
properly
decimal
aligned
would
be
13.4.
A
closer
approximation
of
the
square
root
of
181,
then,
is
13.4.
If
more
decimal
places
are
desired,
then
another
couplet
(00)
is
used
with
the
remainder
each
time
for
each
decimal
place.
To illustrate, using remainder 144;
Remainder
———TM
Fh
Couplet
added
14400
Subtract
___1340
(134
moved
left
one
place)
pair (1) } 13060
1341 (add 1)
11719
Subtract _ 1341
pair (3) } 10378
1342 (add 1)
9036
Subtract rite 1342
pair (5) 7694
1343 (add 1)
6351
Subtract eee 1343
pair (7) a ee 5008
1344 (add 1)
3664
Subtract __ «14
pair (9) J Ba
Last
successful
1345
(add
1)
subtract 975
1345
(Overdraft)
(Restore)
The
last
successful
subtraction
yielded
the
number
1345,
which
properly
decimal
aligned
would
be
13.45.
A
closer
approximation
of
the
square
root
of
181
then
is
13.45.
If
more
decimal
places
are
desired,
then
another
couplet
(00)
is
used
with
the
remainder
to
give
another
decimal
place.
Addition
of
couplets
and
using
the
remainder
each
time
can
be
used
to
give
any
desired
degree
of
decimal
accuracy.
Remainder
In
the
foregoing
illustration
of
square
root,
the
odd
integers
were
found
by
successively
using
the
last
number
successfully
subtracted
as
the
first
step
in
each
subtract
pair
cycle,
then
adding
1
for
the
second
step
of
the
cycle.
The
odd
integer
can
also
be
found
by
adding
1
to
the
last
number
successfully
subtracted
in
the
first
step
of
the
new
subtract
cycle,
and
for the
second
step
using
the
last
number
without
adding
1.
In
other
words,
mathematically
it
does
not
matter
in
which
step
of
the
subtract
pair
that
the
1
is
added;
the
sum
of
the
two
steps
will
still
result
in
the
next
odd
integer.

8-1-65 ELECTRONIC CALCULATOR 132 Section 2
TEMPORARY SERVICE MANUAL Page 7
To illustrate using 25:
25 24 24 22
- 1 - 0 - 2 - 1
24 24 22 21
Subtract ‘nano,
pair
(1) (3)
21 18 16 12
222 ae. ae - 3
18
16
12
9
9 4
5. so8:
4 0
ene ee eel
This is the method used in the EC-132 logic. In the first step of each subtract cycle 1
is effectively added to the last number successfully subtracted, without, however, affecting
the retention of the last number. As the second step in each pair, the retained last number
is subtracted. If both pairs of subtracts are successful, then 1 is directly added to the
last successfully subtracted number, which then is used in the next subtract cycle. It is
important to note that each subtract in a pair of subtracts must be successful before the
number representing the last successful subtract is actually changed.
In general terms, the EC-132 handles the square root problem as follows.
The number begins in RI] and the Square Root key is pressed. First, Rl, R2, R3, and R4
are shifted up to put the number in R2, then R1 and RO are cleared out. R2 and RI are then
shifted to left twice to put a couplet into Rl. Next, the subtract operation begins with the

Section 2 ELECTRONIC CALCULATOR 132 8-1-65
Page 8 TEMPORARY SERVICE MANUAL
answer (the odd order integer) being developed in RO. The subtract cycle continues until
there is an overdraft, then the overdraft is cleared out by addition, and another couplet is
shifted into Rl. For every couplet that is shifted into Rl, RO is shifted left once. Thus,
there is always one digit in the answer for each couplet in the original number. The answer
is thus developed, digit by digit, in RO. At the end of the problem, R3 and R4 are shifted
down, and RO is shifted up into R1; these operations are done simultaneously, so it takes
i
only one pass through the delay line. o>}

Section
2
ELECTRONIC
CALCULATOR
132
8-1-65
Page
10
TEMPORARY
SERVICE
MANUAL
oO
BEGIN
LPC
2
|
J
SET
DPS
RESET
DPS
pPce |
INCREMENT DPC
SET
FUNCTION
FF'S
Pc
4
|
DPC
SETS
TO
2
OR
4
bagged
OPC
SETS
TO
16S
SHIFT
UP
RI-R4
SHIFT
R1
LEFT
SHIFT
R2
LEFT
(VIA
1162)
UNCLAMP
EPC
INHIBIT
DISPLAY
CLEAR
RO
DECIMAL
ALIGN
COMP.
OF
D.
POs.
R1-(RO+1)
PC STEPS
11 TO 8
BY
Ca
RO +1
NO
NOTE:
DPC
ZERO?
IN péa — Dec. Pos. odd, DPC sets
to 4.
— Dec. Pos. even, DPC sets
to 2.
IN
PCs
~(RO+)is
via
Carry
FF
set,
ADD
RO
TO
R1
which sets D Catr to 9. ;
IN
Pott
~
RO+1is
via
0-057,
which
cat
~
|
PC
413
|
ee oenaes
IN PG14 —- (RO+ fis via 0-079, which
eg hk adds 1 to A Catr.
R1+(RO+1) and Shift RO
Left are accomplished in | Pc 14 |
the
same
line
pass.
NO
DPC
ZERO?
OPS SET?
SET 0PS
DPC SETS TO 16'S
COMP, OF D. POS.
DPS SET?
SET DPS
OPC SETS TO 16'S
COMP. OF D. POS.
R1 +(RO+1)
xES DPC ZERO?
SHIFT
RO
PC
STEPS
14
TO
LEFT
3
(VIA
1163)
SHIFT UP RO TO R1
SHIFT DOWN R3 & R4
RESET CF
CLAMP EPC TO 0
(VIA ECFD4)
RESET
FUNCTION
FF'S
SQUARE
ROOT
FLOW
CHART
ENABLE
DISPLAY
D-132-5W

8-1-65 ELECTRONIC CALCULATOR 132 Section 2
TEMPORARY SERVICE MANUAL Page 11
B. SQUARE ROOT FLOW CHART
The Square Root Flow Chartis a graphic analysis of the logic operations of the EC~132
Square Root function. The Flow Chart is divided into blocks that contain pertinent major
steps in the logic operations. Since the Square Root function is a sequential operation that
is controlled by the Phase Counter steps, major areas of the logic are designated as to the
PC step in which they occur.
The explanation of the Flow Chart is based upon the fact that the Service Technician is
already familiar with the functional operations of the EC-130. Most of the logic operations
in Square Root function are the same as in other functions of the EC-132, The differences
lie in the sequence of operations, and the Phase Counter step in which they occur. There-
fore, those operations that are the same and which are already understood will be mentioned
briefly, if at all.
SQUARE ROOT - BEGIN
Square Root begins with depression of the Square Root key which closes Square Root reed
switch and Common Function reed switch. The reed switches, in turn, initiate KBD, and en-
able Square Root and CF FF's. DPS set and DPC set to 16's complement of the decimal
position are exactly as in other functions.
SQUARE ROOT - PC STEP 1
Display is inhibited by PSZ3 False at A-256 in the Display Logic. This is the same as in
the EC-130 except for the gate number. Decimal Align is controlled by. O-075 which controls
MAI1L3 True (Align R1 left).
SQUARE ROOT - PC STEP 2
DPC sets to either 2 or 4, according to whether the Decimal Point switch position is an
odd number or an even number. The logic of this setting is explained in Decimal Point
Counter logic discussion. ss ot Clare By cL. Re
“Y Ri Ch~ek Rracl & CIN do yn)
RO is cleared of data by two operations. First; RO data frorn the Deiay Line is inhibited
from incrementing A Counter by RCRO3 True at O-181. RCRO3 is developed by I-074
controlled by 0-073. PC81, PC4l, PC22, and PC11 specify PC step 2, and TRO4 specifies
RO time. When all inputs to O-073 are False, output is False and is inverted True by I-074,
designated RCRO3 (Clear RO). Second; RCRO3 True makes CRD9 True via O-169. CRD9
True resets D to zero and destroys R4 data, which otherwise would be placed in RI.
DPS is reset during PC step 2 by RCRO3 True at input 1145 on the reset input of DPS FF.
Rl through R4 shift up, which clears Rl for use in the Square Root operation, is con-
trolled by 0-072. RSUQ6 False from 0-072 makes RSUL3 True from 1-129, which in turn
enables A to D and D to B shifts from Rl through R4 time (TFG1 on 0-072).

Section 2 ELECTRONIC CALCULATOR 132 8-1-65
Page 12 TEMPORARY SERVICE MANUAL
SQUARE ROOT - PC STEPS 4 & 6
The net result of PC steps 4 and 6 is to shift R2 left by couplets (2-digit groups). Shift
R2 left is controlled in both PC steps by 0-068. PC81, PC42, and PC11 will be False during
PC steps 4 and 6. When all inputs to O-068 are False, output is False and is inverted True
by 1-069, designated ML2Q3 (Shift R2 left in Square Root). ML2Q3 True is applied through
O-085 to I-086 and Inverted False, designated M2L4. M2L4 False enables 0-126. TFE2
and TFF1 False at O-126 specify R2 time, and TCX5 specifies column times. (For TCX5
logic, see Register Expansion discussion.) When all inputs to O-126 are False, the output
is False, designated RS2L6 (Shift R2 left), RS2L6 False applied through A-128 to I-129 is
inverted True, designated RSUL3 (Shift Up or Left). RSUL3 controls shifts left of R2
through O-150 and O-154.
SQUARE ROOT - PC STEPS 5&7
The net result of PC steps 5 and 7 is to shift R1 left by couplets. Shift Rl left is con-
trolled in both PC steps by 0-066. PC81, PC42, and PC12 will be False during PC steps
5 and 7. When all inputs to 0-066 are False, output is False and is inverted True by I-067,
designated ML1Q3 (Shift R1 left in Square Root), ML1Q3 True is applied through O-087 to
I-088 and inverted False, designated M1L4. MI1L4 False enables 0-123. TR14 specifies
Rl time, and TCX5 specifies column times. When all inputs to O-123 are False, the output
is False, and is designated RS] L6 (Shift Rl left). RS1L6 False is applied through A-128 to
I-129 and inverted True, designated RSUL3 (Shift Up or Left). RSUL3 controls shifts left of
Rl through 0-150 and 0-154.
Each shift of Rl left increments DPC by 1 through O-102 at the toggle input of DCl.
DSZ3 False specifies DPC not zero, and MI1L4 False specifies shift Rl left. When HOME1
goes True at O-102 with all other inputs False, output of O-102 goes False to True and in-
crements DPC by l.
SQUARE ROOT - PC STEP 8
To produce the desired mathematical result, RO data is incremented by 1 before sub-
tracting the data from Rl. Since a subtract is a complementary add, subtract is accom-
plished by counting in D Counter to take the complement. The complement is then shifted
D to A and Rl is added. Incrementing RO data (RO + 1) is simply accomplished by setting
Carry FF via 0-064, which controls the development of ASCQ3 True (Set Carry in Square
Root). Carry FF being set enables AC gate 1303 at set input of D5 FF, which then is set by
CRD9 at CIROBI5 time (before C2RO data is counted in D Counter). The net result, then,
is that the count in D starts from 9, or 1 is effectively added to RO data. It-is important to
remember, however, that RO data is counted into A Counter and into D Counter simultane-
ously. When the D to A shift occurs, which places the complemented RO data in A, an A to
B shift is generated which preserves the RO data unchanged in the data sequence.
(ROA)
Subtract (RO ~- [) from R1 is partially accomplished by counting RO data in D Counter and
shifting
Dto
A.
The
final
step
in
the
complementary
addition
is
accomplished
by
counting
Rl
data in A on top of the complemented RO data
a

8-1-65 ELECTRONIC CALCULATOR 132 Section 2
TEMPORARY SERVICE MANUAL Page 13
SQUARE ROOT - PC STEP 9
The subtract cycle in PC step 8 may leave Carry FF set at Home time, which would set
COF FF and indicate an unsuccessful subtract (overdraft). If this occurs, the number in
Rl must be restored. Therefore, COF set is used as a decision point at the beginning of PC
step 9.
If COF is set, PC steps to 14 at the end of PC step 9 via 1172 on PC4 FF set input. This
step jump is covered in the Phase Counter discussion. The logic action in PC step 14 is.
to restore the number by adding R1 to (RO +1), which is the opposite of PC step 8 subtract
cycle. This addition will be covered in PC step 14 discussion,
If COF is not set, which indicates a successful subtract cycle, the Phase counter steps
to 10.
SQUARE ROOT - PC STEP 10
In the discussion of Square Root Mathematics it is pointed out that the subtract cycles are
carried out in groups of two, which eliminates the last step of dividing by two. The first
subtract cycle adds 1 to RO data, and then subtracts. The second cycle subtracts RO directly.
Rl - RO is a straight complementary addition as in a usual subtract problem.
Ri - RO is controlled, exactly as in PC step 8, by O-056 which develops MSU4. MSU4
then controls a normal complementary add cycle, which is a subtract. The only difference
between PC step 8 and PC step 10 is that in step 8 one (1) is effectively added to RO data as
a part of the subtract cycle, and in step 10 no addition of 1 to RO data takes place.
SQUARE ROOT - PC STEP 11
The subtract cycle in step 10 may leave Carry set at Home time, which would set COF
FF and indicate an unsuccessful subtract (overdraft). If this occurs, the number must be
restored. Therefore, COF being set is used as a decision point at the beginning of step 11.
If COF is not set this indicates a successful subtract, which is indicated in the data by a
direct addition of 1 to RO data. This is controlled by 0-057, which develops RIAQ6 (In-
crement A Counter in Square Root). RIAQ6 is inverted True by I-139, designated ASA13
(Set Al FF). ASA13 enables AC gate 1291 on A Counter Al FF. When A Counter is reset to
zero by CRAY just before RO data is counted in, Al FF becomes set which adds 1 toA
Counter. Then, when RO data counts in on top of the 1 in A Counter, effectively 1 is added
to RO data, which indicates the successful subtract.
When COF is not set this indicates not only a successful subtract but a possibility of
more successful subtracts. Therefore, the Phase Counter steps to 8 to perform another
subtract cycle, Step 11 to 8 is controlled by gate 1176 on PC4 FF and is explained in the
Phase Counter discussion.
If COF is set, this indicates an unsuccessful subtract (overdraft), and the number must be
restored. This is accomplished in step 12. Step 11 to 12 is controlled by gate 1172 on PC4
FF, and is explained in Phase Counter discussion.