Subjects

**Multiply**with 10key machines- Mechanical "Data buss" and the link with to days computer architecture

The Ascota 114 and 314, the Precisa 164-12 and 166-12, the Olympia RA16 and 20, and the Olivetti multisumma 22 and 24 types **store the multiplicand in an extra register**, located on the bottom of the machines, (please see the pictures to the left) This **to enable the automatic multiplication**. Most of the listed types go a step further, they have the short multiplication implemented. Times 8 is not 8 cycles but 3. First time ten in one and mines two, in two machine cycles.

The register for the multiplicand is on the picture in the park position. When the number is inputted and loaded in the pin box and the multiplication key is pressed, the register is moved towards the gear racks and put on those to loaded the number, (all digits at ones).

The register for the multiplicand is on the picture in the park position. When the number is inputted and loaded in the pin box and the multiplication key is pressed, the register is moved towards the gear racks and put on those to loaded the number, (all digits at ones).

The actual, simplified, multiplications works as follows:

On this more in detail picture, you see the register is hold position by a plate with steps (On top, mid of the picture). This plate turns to the right and the multiplicand register moves one digit at each step upwards. This is used to sequential access each individual digit of the multiplicand. As often said a multiplication is repetitive additions, so as long the first digit is not zero, an addition of the pin block content, to the total register, is performed and this multiplicand digit is with one decreased. When the first digit reaches zero the multiplicand register shifts one step to the next digit to determine the adds of the tens, the pin block is shifted one position as well. Like so for the hundreds etc. The pin block size is limited so the multiplicand is.

The Astra 110 has a "R+" key. Holding down that key, will add the content of the key board / pin box, each cycle to the result register. After those cycles the SSW shift one position to the left. So the next time pushing and holding the R+ key for instance 2 cycles, it multiplies times 20. Next p X 100 etc. You have the possibility to do so until the SSW comes in the end position. With that we have a limiting factor of this way of using this Rocket Segment technology for multiplication.

When you don't like to print each individual adding of this multiplication procedure, there is a somewhat hidden key / switch to turn it off (on the side to the left, down near the cap release).

**Mechanical "Data buss" **and the link with to days computer architecture

We know data busses in current computers as common medium between for instance the CPU and memory. They are transporting digital signals, ones and zeros, between the digital computer parts / units. In rocking segment machines, with more complex functions implemented, such as used in bookkeeping machines, manufacturer like Astra / Ascota used the word data buss for the horizontal gear rack as well (as seen picture below) a decimal values data bus. This is a clever way of looking to the machines. Why not see the racks as a connection between the calculator unit (CPU) and the printing unit, as shown on second the picture below. In fact and I like to refer to the manufacturer chapters of the Astra Ascota 314 and 170 for more pictures, you may seen the keyboard as well connected to the data buss.

The 170 has several peripherals like a external memory, a punch card- and punch band reader, a divider and multiplication unit who all have access to this central data buss, the racks.
You may have noticed that the racks can be modified as well. The right part is at this version having no teeth on the side we see it on the photo, it is however possible to use the same bar as on the left part is used to extend the number of units to access the data bus. (The upper part has teeth, register K is located there.) This possibility is clearly shown by the side walls of the racks. They have the holes to mount many more units on the buss. Good example of modular design in the 1950 thy's.

A video showing the manual multiplication of 45 times 12345679 by adding a zero to the multiplicant

A video showing an automatic divide of 555555555 by 45 is 12345679. More information how the calculation is done

You might think that I make a mistake here, no I don't. Although I have written at the "How do they calculate" introduction page, that the Rocking Segment technology is not highly suitable for multiplication, there is one

For instance when you have entered 1234 and enter a zero you get 12340 = 1234 x 10. This makes it very usfull in the multiplication of numbers in general. For instance when you like to multiply 1234 x 32 you add 1234, 2 times followed by a 0 entry. And add 12340, 3 times.

In fact it is surprisingly simple, that I wonder that this feature is not more often used in earlier machines this way at 10 key Rocking Segment technology machines. A few companies have implemented it the seventies: Astra 1xx and 314; Precisa 164-12; Walther SMxx series and Olivetti.