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Brunsviga 13RK Instructions

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Contents 1 Clearing the Decks 2 The Iterator Crank 3 Clearing Individual Registers 4 Entering data 5 Arithmetic Operations 5.1 Addition 5.2 Subtraction 5.3 Multiplication 5.4 Division 5.4.1 A note about the iteration counter 5.4.2 Long Division 5.4.3 More decimal places, please! 5.5 By the way, what's that gubbins right beneath the crank? 6 Chained calculations and register transfers 6.1 Register transfer

[edit] Clearing the Decks

Full machine reset:

• Make sure the Iterator Crank is in the downward, locked position.
• If necessary, use the Accumulator Shift lever to move the accumulator to its leftmost position by repeatedly moving the lever to the left. Each operation of the lever will move the accumulator carriage one place. In the neutral position, the ends of the accumulator carriage will be flush with the sides of the unit, and the one's digit will be beneath the one's drum of the input register.
• Set the Clear Mode Switch upward to the •• position.
• Slowly pull down the Master Clear lever all the way forward.
• The Master Clear lever should return on its own, but if the machine is old you may need to gently encourage it

[edit] The Iterator Crank

The Iterator Crank is the heart of the operation. The crank turns the Input Register drums and either adds or subtracts that value into the Accumulator. A forward (clockwise) crank adds, a backward (counterclockwise) crank subtracts. The crank is in its home position when the handle is straight down and the pin is locked in the bracket. Once started, a cranking action must be completed until the crank is again in the neutral position. An erroneous crank can be undone by cranking in the opposite direction after the previous motion is complete. No other calculator control will function while the drums are being cranked. Make sure you finish the turn before pulling any other levers or making any other settings.

[edit] Clearing Individual Registers

In addition to the full machine reset, you can clear the individual registers separately:

• The Input Clear lever on the left side of the machine resets the Input Register to zero, and moves all the setting tabs to the top.
• The Counter Clear lever, upper right, resets the Iteration Counter to zero and clears the Iteration Indicator. If the Clear Mode Switch is in the up (••) position, the Input Register is also cleared.
• The Accumulator Clear lever is the smaller of the two levers conjoined at the lower right. It resets the accumulator to zero.

[edit] Entering data

All data are entered via the Input Register. Each digit has a setting tab beneath it. Move the tabs to the correct value and confirm the entry in the Input Register Display.

[edit] Arithmetic Operations

[edit] Addition

Adding a column of figures is straightforward. Enter each figure into the Input Register and make one forward turn of the Iterator Crank. The Accumulator will display a running total and the Iteration Counter will report how many figures were entered.

Example: Add $6.95, $4.95 and $19.95. You may find it convenient to move a sliding indicator to between positions 2 and 3 on the Input Register and the Accumulator to separate dollars from cents.

1. Start with a Full Machine Reset as above
2. Enter 695 on the Input Register
3. Make one forward turn of the Iterator Crank
4. Enter 495 on the Input Register
5. Make one forward turn of the Iterator Crank
6. Enter 1995 on the Input Register
7. Make one forward turn of the Iterator Crank
8. Read the sum, 3185 as $31.85
9. Note the value 3 in the Iteration Counter representing three values accumulated.

[edit] Subtraction

Any value can be subtracted from the value in the Accumulator. Enter the value to be subtracted in the Input Register and make one reverse turn of the crank. The Accumulator will be reduced by the input value and the counter will be decremented by one.

Example: Subtract $2.50 from $19.95

1. Start with a Full Machine Reset as above
2. Enter 1995 on the Input Register
3. Make one forward turn of the Iterator Crank to transfer this value to the Accumulator
4. Enter 250 on the Input Register
5. Make one reverse turn of the Iterator crank to subtract
6. Read the difference, 1745 as $17.45
7. Note the zero in the Iteration Counter, representing one figure added and one removed.

Note: The unit doesn't handle negative numbers, and you can "underflow" the accumulator. If you see a number starting with a large number of '9' digits, you probably underflowed the accumulator. The difference 4 - 10 we know to be -6, but you will see 9999999999994 on the Accumulator.

[edit] Multiplication

Multiplication is accomplished by staggered addition, just like we all learned in grammar school. Use is made of the Accumulator Shift lever to move the accumulator left and right relative to the Input Register and Iteration Counter. The multiplicand is entered in the Input Register and the multiplier is built up on the Iteration Counter by repeated cranking. The Accumulator Shift lever permits us to take shortcuts: one does not need to turn the Iterator Crank one hundred times. Shift the accumulator two steps to the right and crank once. Done!

Example: Multiply 842 by 123

1. Start with a full machine reset as above. Especially important is to make sure the Accumulator is unshifted.
2. Enter 842 on the Input Register
3. The multiplier, 123, has three digits. Currently the Accumulator is set to add at place one. Press the Accumulator Shift lever to the right twice to move to the hundreds' place (place 3). Note that an indicator in the bottom of the Iteration Counter display has also moved to the hundreds' place.
4. Turn the Iteration Crank one time forward. Note the value 84200 on the Accumulator and 100 on the Iteration Counter.
5. Press the Accumulator Shift lever one time to the left. The indicator on the Iteration Counter display will have moved to the tens' place.
6. Turn the Iterator Crank two times forward. Note the value 101040 on the Accumulator and 120 on the Iteration Counter.
7. Press the Accumulator Shift lever one time to the left. The indicator on the Iteration Counter has now returned to the ones' place.
8. Turn the Iterator Crank three times forward.
9. Read the product on the Accumulator, 103566. Note the count on the Iteration Counter, 123. Done!

[edit] Division

[edit] A note about the iteration counter

Clear the Iteration Counter or do a full machine reset. If you look at the left end of the Iteration Counter display, you'll see a white indicator. This tells you that the Iteration Counter is in an undefined state. It has neither been used to count additions or subtractions. Turn the Iteration Crank one turn forward. The white indicator disappears and 1 appears on the counter. Turn the crank back one place. The counter reads zero, but the white indicator is still gone. This is an active zero, the result of one count forward and one back. Turn the crank back once again. The Iteration Counter underflows and reads 99999999.

Clear the Iteration Counter again. Turn the crank backwards once. The white indicator disappears and a red 1 appears in the counter. The counter is in subtraction counting mode. If you turn the crank forward once you'll get a red zero; if you turn it forward once more then the counter will underflow with a red 99999999.

The order of operations is important to the Iteration Counter. When the white neutral indicator is visible, the Iteration Counter is neither in Addition Mode nor in Subtraction Mode. The first turn of the Iterator Crank will set the mode for calculations to follow. Usually all we care about is the Addition Mode. We use the Subtraction Mode for long division.

[edit] Long Division

As we performed multiplication by repeated addition (shifting the accumulator as necessary), we do division by repeated subtraction (again, shifting the Accumulator as needed). This is similar to the method used in elementary school but we can use the easy mechanical action of the calculator to obviate the need for estimating partial quotients. Everyone hates that!

We start by loading the dividend into the Accumulator. This affects the Iteration Counter so the next step is to clear that. Then we load the divisor into the Input Register. Shift the Accumulator to the right as far as you can and turn the Crank backwards once. If the Accumulator underflows and you hear a bell ring, you've shifted too far. Undo your crank (i.e. turn it forward once; you'll hear the bell again) and shift the Accumulator left once. Crank backwards as far as necessary to ring the bell, crank forward once, shift left. When you can't shift anymore, you're done! Read the quotient in red figures in the Iteration Counter and read the remainder in the Accumulator.

Example: divide 256 by 7

1. Start with a full machine reset as above
2. Set 256 on the Input Register and turn the Iterator Crank one time forward to load the accumulator.
3. Clear the Iteration Counter. If the Clear Mode Switch is set to the upward •• position, the Input Register will clear as well. You may find this convenient.
4. Enter 7 on the Input Register.
5. Shift the Accumulator to the right. If you shift it two places you'll start by dividing 7 into the 2 of 256. (See this for yourself with a quick crank backwards [ding] then undo this with a quick crank forwards.) Move the Accumulator once to the left and we'll start by dividing 7 into 25.
6. Turn the crank backwards until the bell rings, then forward until the bell rings again. Or watch the Accumulator decrease until you can see that subtracting another 7 is pointless. You should see 30 in the Iteration Counter and 46 in the Accumulator. You have just subtracted 30 sevens from 256 and you have 46 left over.
7. Shift the Accumulator to the right again.
8. Turn the Crank backwards until the bell rings again or you can tell that you're about to underflow the Accumulator. If the bell has rung, you underflowed and you need to turn once forward to undo the underflow.
9. Read the quotient, 36, in the Iteration Counter and the remainder, 4, in the Accumulator. You're done! The answer is 36⁴/₇.

[edit] More decimal places, please!

You may need to expand that ⁴/₇ a little bit, especially if you need the value for later. No problem. Where the decimal place is is completely up to you. The dividend, 256, doesn't need to be at the low end of the Accumulator. Just shift the Accumulator to the right a few places before you start. You'll use the sliding reference pointers to keep track of the decimal point.

Example: Divide 256 by 7 and make room for four decimal places.

1. Shift the Accumulator to the right four times. Place 5 on the Accumulator will be under the ones' place on the Input Register (there's a little arrow there to show you where you're at). The Iteration Counter's active indicator will be in the fifth position as well.
2. Enter 256 on the Input Register.
3. Turn the Iterator Crank forward once.
4. Above the Iteration Counter, move a sliding indicator so that it's just to the right of the 1 digit that just appeared. On the accumulator, move an indicator just to the right of the 256 on the display. These are your decimal points for the rest of the calculation.
5. Clear the Iteration Counter.
6. Enter 7 on the Input Register.
7. Shift the Accumulator once more to the right.
8. Turn the Crank backwards until you hear the bell, then once forwards (the bell will ring again.
9. As above, shift the Accumulator to the left once and crank backwards again. Repeat until you can't shift any more.
10. When you're done, you should see the quotient, 36.5714, in the Iterator Counter display. In the Accumulator you'll see the remainder, 0.0002. You should consider whether that remainder is enough to warrant rounding up the last place of the quotient. In this case, since 2 is less than half of 7, you won't want to round up. You're done!

[edit] By the way, what's that gubbins right beneath the crank?

Bracketing the crank is a mechanism that moves forward and back. It's tied into the Accumulator Shift lever and gives you a speedier alternative for shifting the Accumulator. Once all the inputs are set, you should be able to complete a multiplication or division using just that lever and the crank. You won't need to move your hand away at all. Unfortunately, this mechanism seems to be the first to go bad. On my unit the forward motion (right shift) sticks pretty badly and the reverse direction doesn't spring back fully. That's why I use the main Accumulator Shift lever in the examples. It still works.

[edit] Chained calculations and register transfers

Say you have a box with dimensions 12 x 10 x 7. You multiply 12 and 10 and you get 120 in the Accumulator. To multiply that by 7, you have to move that value into the Input Register. In lesser calculators, you'd just have to read off the Accumulator and set the wheels in the Input Register by hand. The 13RK has a better way.

[edit] Register transfer

To move the value in the Accumulator into the Input Register:

1. Pull and hold the Input Clear lever.
2. Pull the Master Clear lever fully forward
3. Release the Master Clear lever
4. Release the Input Clear lever

The value in the Accumulator has been moved to the Input Register. The Accumulator and Iteration Counter have been cleared and you're ready for the next stage of your calculation

Example: What's the volume of that 12 x 10 x 7 box we mentioned above?

1. Start with a full machine reset
2. Set 12 on the Input Register
3. Shift the Accumulator one place right
4. Turn the crank forward once. Note 12 x 10 in the Accumulator
5. Shift the Accumulator back to its normal position
6. Perform the register transfer operation as above
7. Turn the crank 7 times
8. Read 12 x 10 x 7 = 840 from the Accumulator. Done!

Remember to mind where the Accumulator carriage is. If it's shifted away from its home position, you won't get the entire value transferred to the Input Register. This may be a feature.

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