When the case is open, it is immediately clear that the machine is divided into three large blocks:
Click on image for larger view
The power supply section is extremely robust in order to provide the machine with the 350 Watts it requires. This also includes a single electric motor that, by means of rubber belts, serves all the needs of the Programma 101 (cooling fan at the rear, card reader, printer and keyboard).
These rubber belts are the only detail of the machine that was not designed to last forever. In many cases some of these belts, made in a very soft rubber, have literally liquified, transforming themsleves in a sort of awfully sticky black marmalade. Cleaning this stuff away is painstaking, expecially when it drops in the very delicate electromechanical section. The same is true for a single, small cylinder of rubber used in the advancement of the magnetic card that often sticks together all the very mechanisms of the reader, including the read/write magnetic head.
The electromechanical section shows all the previous experience that Olivetti's engineers had in electromechanical calculators.
The keyboard is quite curious. Usually these keyboards have a switch behind each key, and all the switches are arranged in a matrix that is scanned one line at a time by an electronic circuit. In the Programma 101, instead, behind each key is a small lever, and all these levers get into a sort of "mechanical encoder" powered by the motor (fig. 1). This encoder commands a set of switches. The result of all this is that any time a specific key is pressed the switches are maneuvered in a specific pattern. This hardly seems a good idea, and a lot of mechanics is used to encode the machine's 37 keys to 12 switches, but it must be taken in consideration that this section also handles priority encoding (i.e. the contemporary pressure of two keys), keyboard locking in case of mistake and (as far as I understand) a first level of key debouncing. The keyboard shows that Olivetti had a lot of experience with electromechanical calculators and Ing. Perotto found it easier and more reliable to re-use some of the know-how that his collegues had in electromechanical keyboards.
The printer is deceiptively simple. A cylindrical drum rotates behind the paper roll. On the surface of the cylinder all the printable characters are engraved, repeated on 28 columns, one for each printable position. In front of the paper is the ink ribbon, and a single little hammer runs up and down, giving a hitthe paper at the very exact moment when the cylinder behind the presents the required character, that gets thus printed.
The manual speaks proudly of the 30 characters per second the printer is able to handle, and in effects one can see that the the designers tried to do their best from the fact that each column in the cylinder has the series of printable characters repeated twice, so that for each revolution of the cylinder two characters can be printed.
The card reader is even more simple: a slot to insert the card, a set of switches to detect the insertion and a magnetic head. In front of the machine, two switches labeled RECORD PR and PRINT PR give you all the interface is needed. Reading a card is simply done by inserting it into the reader with the RECORD PR switch depressed. Simple as it may seem, the card reader was extremely advanced for that period.
The electronic section is, to put it simply, wonderful. It is well enclosed in a separate box, with an air filter from one side and a cooling fan from the other side. At the top is the delay line memory module with its little driver board. Underneath, 8 large and strictly packed boards are stuffed with discrete components (transistors, diodes, resistors and capacitors) grouped in small "modules". For more detail, see the page about the electronics.