Daro Soemtron 220 User manual

This manual has been reproduced from a 1976 German publication
Daro Soemtron 220
Elektronischer Tischrechenautomat
Bedienungsanleitung
69-220-000-5
We ( www.soemtron.org ) fully recognise the intellectual property rights of the originating source and
will take steps to remove, alter or further acknowledge this document if we are notified of any
infringements. It has been presented in good faith to aid in understanding the inner workings of the
now vintage Soemtron 22x range of electronic calculators.
It has been published by us to disseminate information about the Soemtron 22x range of electronic
desk calculators manufactured by V.E.B. (*1) Büromaschinenwerk Sömmerda, as a project to gather
and centralise whatever information can be found about these increasingly rare early electronic
calculators.
If you have or know of any information, books, drawings, circuits, hardware, test equipment (prufgerat)
or other memorabilia relating to the Soemtron 220, 221, 222 or 224 calculators, their trade names -
Daro or Soemtron, manufactured by - V.E.B. Büromaschinenwerk Sömmerda, please email us at -
[email protected]
This document has been scanned from an original book, processed through an on-line OCR software
package to regenerate the original German text and then automatically translated to English and
imported into Microsoft Word. Layout has been duplicated in line with the original document as much
as possible to retain the flow of the original document. Drawings, circuits and photographs are scans
from the original document.
With this effort in mind some of the syntax in the document may be a little strange. Some portions
have been reworked to be more readable English text but there is obviously more to be done. If you
can help with this, or indeed have any helpful information or comments, please email us at -
[email protected]
Please use, and hopefully enjoy, this in information in the spirit in
which we undertook to generate it - as an information source for an
interesting piece of early calculator history before the advent of
modern electronics, in the days when “hands on” engineers thought
through the problems and challenges of designing equipment with
little resources, to produce the best end product they could.
August 2019 - www.soemtron.org - [email protected] Revised 21/8/2019

TABLE OF CONTENTS Page
l. Introduction 5
Keyboard (graph) 6
2. Description of the structure and equipment 7
Keyboard 7
Display 7
Decimal point means 8
Processing unit 8
Power supply 8
3. Commissioning 9
4. Calculations 10
4.1. Addition 10
4.2. Subtraction 10
4.3. Multiplication 10
4.4. Division 10
4.5. Exponentiation 11
4.6. Memories 11
4.7. Decimal points 11
4.8. Constant factors 12
4.9. Correction 12
5. Input and output capacity 13
6. Calculation examples 14
1. Addition 14
2. Subtraction 14
3. Addition and subtraction in 3 stores
with [netting] 14
4. Multiplication with different Decimal points 15
5. Multiplication with different Decimal points 16
6. Constant factor - average calculation
(2 memory) 16
7. Multiplication by a parenthetical expression 16
8. Exponentiation 17
9. Division 17
10. Division with constant dividend 17
11. Division with constant divisor 18

12. Division with a bracket expression 18
13. Percentage searched 18
14. Numerical value wanted 19
15. Increased value 19
16. Reduced value 19
17. Combination Calculator (3 rule ?) 20
18. Interest calculation after days 20
19. Distribution task (3 memories) 20
20. Payroll with constant factor
[2 memory] 21
21. Conversion of the English currency 22
22. Insurance calculations (insurance) 22
23. Weight calculation 23
24. Subtraction of two Quotients 23
25. Calculation of the cutting speed 24
26. Amortization Schedule 25
27. Invoice control with 3 save 26
28. Series Development [Minus Division] 28
29. Labour Statistics 29
30. Square root calculation after the iteration 31
31. Cubic root calculation after the iteration 33
Appendix: Technical data 35

1. INTRODUCTION
Decades of experience in the design of computing machines have found their
expression in the technical design of the electronic desktop calculator
"Soemtron 220".
A device was developed with the electronic desktop calculator, which
corresponds to the state of the art and significant advantages for its
customers.
High computing power, noiseless operation of the arithmetic operations and
simple operation are characteristic features of the electronic desktop
calculator, with the time compared with the working on an electromechanical
base of automatic calculators high economic efficiency can be achieved.
The electronic desktop calculator "Soemtron 220" solves the most varied tasks
at all levels of commercial and scientific knowledge technical and technical
sector.
The electronic desktop calculator comes in 2 variants - as type 220/1 with a
memory and as type 220/3 with 3 memories - manufactured.
The calculation functions are the same for both models. It accounts for only
the type 220/1, the 2 rows of keys for the memory II and III. This means that
tasks that require more than one memory, not with ETR 220/1.
As an effective means of organization, the electronic table calculating
machine "Soemtron 220" is involved in the rational solution of arithmetical
tasks their many variants take a decisive position and themselves prove by
its great performance everywhere, where you look his served.
5

KEYBOARD of electronic desktop calculator
1. Decimal point adjustment.
2. Delete key
3. Correction key
4. Decimal point key
5. Numeric Keypad
6. Sign key
7. Multiplication key
8. Addition Key
9. Result key
10. Subtraction
11. Division key
12. Exponentiation
13. Memory Addition
14. Memory subtraction
15. Memory recall without deletion
16. Memory recall with deletion
6

2. DESCRIPTION OF CONSTRUCTION AND EQUIPMENT
The electronic desktop calculator type 220 is a fully transistorized
device. In addition to all the throat operations of the elementary
calculation, he performs extensive combination calculations and
exponentiation tasks quickly and mathematically exactly.
The machine is built according to the modular principle, so that a secure
maintenance is guaranteed.
The electronic desktop computer consists of the following modules:
Keyboard
The keyboard is arranged clearly and within reach. It is divided
in 3 key groups:
Left key group: Numeric keypad
0-9 Digits
Decimal point dial
Lö Delete key
C Correction key
Decimal point key
Middle button group : Function keys
# Enter a negative number
Xn Exponentiation
X Multiplication
: Division
+ Addition
- Subtraction
= Result
Right button group: Memory function keys
* Memory recall with deletion
▽Memory recall without deletion
+ Memory addition
- Memory subtraction
7

DISPLAY DEVICE
The input and output values are displayed clearly legible in the display
device by means of digital display tubes.
DECIMAL POINT DEVICE
To the left of the keyboard is a thumbwheel for setting the decimals. Before
starting an arithmetic operation here is the required to set the decimal
place. The Decimal point is indicated by a red dot in the display unit
shown.
COMPUTATION UNIT
The "computing unit" assembly comprises all the electronics of the machine,
including the ferrite core memory and the control system of the machine
Display unit.
POWER ADAPTER
The power supply generates the necessary voltages of the machine.
Form and colour match the modern line.
Dimensions and mass make an effortless job change.
An advantageous utilization of the workplace is due to the relocation of
weight on 3 feet guaranteed.
8

3. COMMISSIONING
The computer is designed for connection to the following mains voltages:
110V +10 % 50—60 Hz
-15 %
127V +10 % 50-60 Hz
-15 %
220V +10 % 50—60 Hz
—15 %
242V +10 % 50—60 Hz
—15 %
From the factory the automaton, if no other delivery agreement exists
supplied for connection to 220 V mains voltage. A change may only be done
by a specialist.
The set mains voltage is at a selector switch located on the Power supply
is located, to recognize from the outside through the breather.
For commissioning, the computer must be connected to the mains using the
protective earthing cord provided after checking the setting. After
pressing the switch on the lower right side of the Cover is the
operational readiness of the machine by a red indicator lamp is displayed
in the display unit. Before the start of the calculation to press the
(Delete) and (C) keys. The display tubes adjust to the digit "0" and the
calculator is ready for operation.
Opening the calculator is permitted by special tools only for repair
purposes by trained professionals.
9

4. CALCULATION OPERATIONS
4.1. Addition Button
Additions are possible in the calculator and in the
memories.
Press the (+) button to enter the addend values.
The total is displayed after pressing the (=) button.
The addends are entered into the calculator by (+)
In the memory I, II, III (+)
Memory recall without deletion I, II, III (▽)
Memory recall with deletion I, II, III (*)
4.2. Subtraction
Subtractions are possible in the calculator and in the
memories.
The minuend is entered by the (+) button.
Press the (-) button to subtract the entered values.
The total is displayed after pressing the (=) button.
The subtrahends are entered into the calculator by (-)
In the memory I, II, III (—)
Memory recall without deletion I, II, III (▽)
Memory recall with deletion I, II, III (*)
4.3. Multiplication
The multiplicand is entered by the (X) key.
Pressing the (=) key is used to transfer the multiplier to the
calculator, the multiplication is triggered and the product is
displayed.
If a sum or a difference in the arithmetic unit has been formed before
or after entering the multiplicand, this sum or difference becomes a
multiplier when the (=) key is pressed.
Example : a X b = c
a(b + c) = d
(a — b) c = d
The displayed product can be processed further (see also
Calculation example 7).
4.4. Division
The dividend is entered by pressing the (:) key. After entering the
divisor, press the (=) button to start the display process
10

and the quotient is displayed. If a sum or a difference is formed before
or after entering the dividend in the calculator, this sum or difference
becomes the divisor when the (=) key is pressed, and with this the
division is automatically executed.
Example : a : b = c
a :(b + c) = d
(a — b) : c = d
The calculated quotient, which is displayed, can be processed further
(see also calculation example 12).
4.5. Exponentiation
The base is entered by the (X) key. Each further press of the (Xn) key
increases the exponent by one. The power is automatically displayed (see
also calculation example 8).
4.6. Memories
All input values, results and constant factors can be stored in an
additive and subtractive way. Negative values are mathematically
processed correctly.
Values stored in the memories can be queried as often as desired by
pressing the (▽) key, whereby the value transferred in sequence is
retained in the memory. It is possible to transfer values from one memory
to another with the correct sign.
Example : (▽) - Memory I, then
(+) - Memory II
By pressing the (*) button (*I, *II, *III) the corresponding memory is
called up and deleted at the same time.
The value in the calculator can be processed further. Pressing the
(Delete Lö) key does not clear the memories.
Should the memory contents be checked during a calculation process.
without the last displayed value, eg. If the result or operand is lost,
proceed as follows:
The displayed value can be transferred to a calculation register by
pressing the (+) key. Thereafter, the memory can be queried, so that the
occupancy or content is known. By pressing the (=) - key the value in the
calculation register is displayed again..
4.7. Decimal point facility
The number of decimal places is set before the beginning of the
calculation by the knurled wheel to the left of the keyboard. When
setting the decimal point, the highest decimal place must be used. The
following decimal places are adjustable:
1-2-3-4-6-9-10-11-12—14
If the thumbwheel is set to "0", it is calculated without decimal places.
The setting "Z" is irrelevant for the type 220.
11

After pressing the (,) - key (Decimal point key) appears at this point
the numbers 0 and 1 on top of each other to indicate the entered
Decimal place.
If a function key is pressed, the value automatically moves to the
appropriate position.
Example : 71,5 X 22,123 = 1 581,795
Decimal point position 3
Enter 71,5 X 71,500
Enter 22,123 = 1531,795
Example : 4,73 : 2,4 = 1,97
Decimal point position 2
Enter 4,73 : 4,73
Enter 2,4 = 1,97
Example : 720,1 : 11,23 = 64,122 9
Decimal point position 4
Enter 720,1 : 720,1000
Enter 11,23 = 64,1229
In the last example, the number of decimal places to set depends on the
result, which is desired with 4 decimal places.
After the decimal place zeros are filled up automatically.
The decimal position must be maintained during the computation process,
you may be added values in the memory or be returned from the memory.
The results (products and Quotient) are automatically rounded in the last
place, IE. from paragraph 5 is rounded up.
The decimal position must be maintained during the computation process,
you may have added values to the memory or be returned from the memories.
Example : Decimal point position 6
1,000000 : 6,000000 = 0,166667
Decimal point position 3
2,58 X 3,01 = 7,766 (7,7658 ≈7.766)
4.8. Constant factors
During multiplication, the exponentiation (Xn key) can be used for the
calculation with a constant factor.
By pressing the (X) key, the multiplicand is adopted as a constant
factor. After entering the variable multiplier, press the (Xn) key. The
respective product is displayed (see also calculation example 6):
4.9. Correction
If you have not yet pressed any function keys, you can delete an entry by
pressing the (C) key. If a function key is pressed after entering the
digits, the correction is made by pressing the (Delete) key. The bill is
to be repeated.
12

5. INPUT AND OUTPUT CAPACITITY
The capacity of the electronic desktop calculator "Soemtron 220"
is in input and output of 15 digits.
Multiplication whole: numbers
The maximum positions of the multiplicand and the multiplier must not
exceed 15 in total.
Example: 9 999 999 X 99 999 999 = 999 999 890 000 001
Multiplication of decimal places
When multiplying decimals, the sum of the digits before the Decimal point
of the multiplier and the multiplicand must not be greater than the
digits of the [ad] remaining before the decimal point.
Example: 9,999,999 999 X 99 999,999 999 = 999,999 999,890,000
Division of whole numbers
The digits of the dividend and the divisor to be entered in the division
can be a maximum of 15 digits, the quotient always being smaller.
Example : 999 999 999 999 999 : 999 999 999 999 999 = 1
Division of decimal places
When dividing numbers with decimal places, make sure that
the quotient increases if the divisor is less than one.
Example : Decimal point position 9
456,123 578 000 : 0,051 = 8 943,599 568 627
456,123 578 000 : 0,005 1 = 39 435,995 686 275
456,123 578 000 : 0,000 51 = 894 359,956 862 745
456,123 578 00u : 0,000 051 = Overrun
If the capacity is exceeded, the indicator goes off The keyboard is
electrically locked. The lock is released by pressing the (Delete) and
(C) keys.
13

6. CALCULATION EXAMPLES
1. Addition
Example : 512 + 309 =821
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 0
2. Enter 512 + 512
3. Enter 309 + 309
4. = 521
2. Subtraction
Example : 461 - 207 = 254
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 0
2. Enter 461 + 461
3. Enter 207 - 207
4. = 254
Example : 397,98 - 612,17 = 214,19 –
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 2
2. Enter 397,98 + 397,98
3. Enter 612,17 — 612,17
4. = 214,19 —
3. Addition and subtraction in 3 stores with nett balance
Example :
I II III
467 533 650
890 123 —2400
---- ---- ------
1357 — 656 = 701 + (—1750) = 1049—
14

Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Clear the memory *I, *II, *III
2. Decimal point position 0
3. Enter 467 +I 467
4. Enter 890 +I 890
5. Recall 1 1357
6. Enter 533 +II 533
7. Enter 123 +II 123
8. Recall *II 656
9. —I 656
10. Recall I 701
11. Enter 650 +III 650
12. Enter 2400 III 2400
13. Recall *III 1750 —
14. +I 1750 -
15. Recall *I 1049 —
4. Multiplication with different deci al points
Example : a) 1234,56 X 17,5671 = 21 687,639 0
b) 5 678,123 X 0,000 = 11,356
c) 1,1 X 9576,5432 = 10 364,1975
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
a) 1. Decimal point position 4
2. Enter 1234,56 X 1 234,560 0
3. Enter 17,567 1 = 21 687,639 0
b) 1. Decimal point position 3
2. Enter 5678,123 X 5 678,123
3 Enter 0,1112 = 11,356
c) 1. Decimal point position 4
2. Enter 1,1 X 1,100 0
3. Enter 9876.543 2 =
10 364,197 5
15

5. Multiplication with different decimal points
Example : 623,3 X 1,22 X 0‚031 = 23,573
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 3
2. Enter 623,3 X 623,300
3. Enter 1‚22 = 760,426
4. X 760,426
5. Enter 0,031 = 23,573
6. Constant factor - average calculation (2 memories)
Example : 22 X 2,70 = 59,40
22 X 2,55 = 56,10
---- ------
5,55 : 2 = 2,63 115,50
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Clear the memory *I‚ *II
2. Decimal point position 2 X 22,00
4. Enter 2,7 +I 2,70
5. Xn 59,40
6. +II 59,40
7. Enter 2,55 +I 2,55
8. Xn 56,10
9. +II 56,10
10. Recall *I 5,25
11. : 5,25
12. Enter 2, = 2,63
13. Recall *II 115,50
7. Multiplication by a parenthesized expression
Example : 958 X (17,12 + 4,3 — 0,030) = 10 911,620
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 93
2. Enter 958, X 958,000
3. Enter 7,12 + 7,120
4. Enter 4,3 + 4,300
5. Enter 0,030 - 0,030
6. = 10911,620
16

8. Exponentiation
Example : 13^5 = 371 293
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 0
2. Enter 13 X 13
3. Xn 169
4. Xn 2 197
5. Xn 28 561
6. Xn 371 293
9. Division
Example : 225 : 5 = 45
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 0
2. Enter 225 : 225
3. Enter 5 = 45
10. Division with constant dividend
Example : 22 33,44 : 22 = 101,52
22 33,44 : 23 = 97,11
22 33,44 : 24 = 93,06
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Clear the memory *I
2. Decimal point position 2
3. Enter 2233,44 +I 2233,44
4. : 2233,44
5. Enter 22, = 101,52
6. Recall ▽I 2233,44
7. : 2233,44
8. Enter 23, = 97,11
9. Recall ▽I 2233,44
10. : 2233,44
11. Enter 24, = 93,06
17

11. Division with constant divisor
Example : 1266,55 : 123 = 10,297
5678,12 : 123 = 46,164
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Clear the memory *I
2. Decimal point position 3
3. Enter 1 266,55 : 1 266,550
4. Enter 123, +I 123,000
5. = 10,297
6. Enter 5678,12 : 5 673,120
7. Recall I 123,000
8. = 46,164
12. Division with a parenthetical expression
Example 750 : (47,623 + 710,21 — 304.1) = 1,653
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 3
2. Enter 750, : 750,000
3. Enter 47,623 + 47,623
4. Enter 710,21 + 710,210
5. Enter 304,1 — 304,100
6. = 1,653
13. Percentage searched
Example : 86 work pieces = 100%
54 work pieces = ?
100 X 54
-------- = 62,8%
86
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 1
2. Enter 5400, : 5400,0
3. Enter 86, = 62,8
18

14. Number sought
Example : 100% = 86 work pieces
62.8% = ?
86 X 62.8
--------- = 54 work pieces
100
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 1
2. Enter 86, X 86,0
3. Enter 62,8 = 5 400,8
4. : 5 400,8
5. Enter 100, = 54,0
15. Increased value
The daily standard of A is 54 workpieces, 68 workpieces are produced. By
what percentage was the standard exceeded ?
Example : 54 work pieces = 100%
68 work pieces = ?
100 X 68
-------- = 125,9 %
54
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 1
2. Enter 6800, - 6800,0
3. Enter 54, = 125,9
16. Reduced value
B produces 120 work pieces per day, which corresponds to a standard
compliance of 130%. What is the norm?
Example : 130% = 120 work pieces
100% = ?
120 X 100
--------- = 92 work pieces
130
Walk through
Sequence of the calculation Function key Display
---------------------------------------------------------------------
1. Decimal point position 0
2. Enter 12000 : 12 000
3. Enter 130 = 92
19