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Olivetti Logos 328, "Un Programma 101 senza programma"

Brand: Olivetti (Olivetti Underwood in the US).
Model: Logos 328.
Origin: Comune di Ivrea, Italy.
Introduction: 1968 at a price of £695 in the UK, around £11700 or US$14900 of 2019!
Description: This rare and robust machine is the first non-programmable electronic desktop calculator made by Olivetti.

Actually, the first desktop electronic calculator is the legendary Programma 101 and the very first is the giantic Elea 9003, but both are programmable computers and the Logos 328 is just a desktop calculator with no programming capability. Although the external design is different, the Logos 328 is a direct descendant of the Programma 101 and inherits its first-generation solid state electronic technology, such as discrete component boards, the acoustic delay line as memory, the mechanically multiplexed keyboard and the printing station.

The Logos 328 is an inexpensive version of the Programma 101 and, in an attempt to cheapen it, Olivetti replaced the cast aluminum housing with ABS plastic and eliminated the programming capability so italians dubbed it "un Programma 101 senza programma"... Actually this machine seems to be the convergence of the functionality of the mechanical super-calculator Logos 27 and 27-2 with the technology of the Programma 101, so it is truly the first electronic calculator made by Olivetti. However this machine was not commercially successful due to the large size and high price and quickly Olivetti replaced the 328 with the new and successful Logos series 200 (240, 245, 250 and 270), so now it is very unlikely to see an example of the Logos 328 and the information on the web is almost null.

The Logos 328 is a very large and heavy machine and it makes small all previous mechanical calculators, just compare it with the contemporary Divisumma 26:

Logos 328 (1968) and Divisumma 26GT (1967)

The overall size is similar to the Programma 101 and the Programma 602, although it weighs about 8 kg. less:

Programma 101 (1965), Logos 328 (1968) and Programma 602 (1971)

Design: The Logos 328 has a rare retro-futuristic design, probably inspired by the space age of the 60s like many other industrial designs of that time. However this design demonstrated to be unsuccessful because Olivetti never used it again. Usually a successful design is reused with some refinements and restyling in new models, this is the case of the Programma 101 that continued with the Programma 602 and then the Logos 2xx.

The body of the Logos 328 has 3 main components:

Keyboard: It is the unique "standard" component similar to any modern calculator. A curiosity is the power switch located under the keyboard that has to be used to the touch... you can see the indicator on the keyboard but not the switch itself!

Printer station: It has a futuristic design with a semicircular printer cover. The curved thick transparent plastic acts as a magnifying glass on the printed paper... a lateral thinking achievement of Olivetti!. The paper roll holder seems to be slidable back and forth but not, it isn't moveable. Particularly it reminds me of the throttle of an aircraft engine... On the right side is located the decimal selector wheel that again has to be used to the touch, the wheel is behind the structure and is not in sight.

Big plastic box: This is the "chip" or CPU with all the discrete components to do the calculations. There are several printed circuits with hundreds of diodes, transistors, capacitors and behind this is located the magnetostrictive acoustic delay line memory. Please, see the pictures below.

The cover is made with ABS plastic of first generation that tends to turn yellow with time and this is the case of my 328, but fortunately the yellowing is very light. In the future I will try to do an oxygenation process to recover the original light gray color.

Because it is too heavy, you should handle the machine with care from the metal base, not from the plastic parts that can be broken just for the own weight!.

Hardware: The Logos 328 inherits a lot of the technology developed for the Programma 101.

Memory: It is implemented via a magnetostrictive metal wire acoustic delay line. Using a transducer a series of acoustic pulses (bits) are inserted into one end of the wire. The pulse travels along the wire at the sound speed and reach the other end where the signal is "read" by another transducer and converted again into an electric pulse. This electric pulse is re-converted into an acoustic pulse by the magnetostrictive effect and re-inserted into the wire and the loop continues indefinitely while the machine is running.
I have no information about the memory capacity, but we can infer it because the calculator uses 6 registers (3 working and 3 for store data) of 24 characters each (22 digit plus decimal point and sign), so the total requirement is for 144 characters. Supposing it uses 8 bit per character like the Programma 101 the total useful memory needed is 576 bits. We can talk about 600 useful acoustic bits necessary for the operation of the 328.

Source of the image:

Keyboard: It uses the same complex mechanically multiplexed keyboard as the Programma 101. Each key moves several metal rods that produces an unique combination on a set of binary switches, that is, each key produces an unique identifying "code" or number transmitted to the chip. The metal rods trends to lock itself, so the keyboard has a mechanism to avoid pressing more than one key at the same time and also has a key to unlock all keys. Olivetti continued using this type of keyboard in some later models like the Logos 55 until it was replaced by the simpler solution of placing one electric switch per key. Detail of metal rods and switches:
The keyboard has 35 main keys plus decimal selector wheel, the round mode wheel and two special keys for All Reset and Keyboard Release. The power switch is located under the keyboard.

Printer: Identical to the Programma 101 with the same moving head and the sync cylinder on the left.

The keyboard, printer station, drive motor and the power supply are mounted in one heavy assembly that represents the half of the total weight of the machine. The keyboard can rotate up to access the binary switches and the internal wiring.

Please see additional pictures below.
Keyboard and controls: Diagram of controls of the Logos 328:


Reset: Clears all registers and reset any pending operation and error condition.
Keyboard clear: Clear the keyboard register after an input error.
Digits 0 to 9 and Decimal Point: Has a capacity of 22 digits plus decimal point and sign.
-: (Negative Sign) Change to negative sign.
3 independent registers: Each colored column (white-green-blue) correspond to an independent register to allow independent operations and results. Each column have the keys T, S, + and - as follows:
T: (Total) Print the register content and clears the register.
S: (Subtotal) Print the register content without clearing the register.
+: (Add) Add to the register.
-: (Subtract) Subtract from the register.
Function keypad:
: (Square) Computes the square.
%: (Percentage) Computes percentages.
: (Square root) Computes the square root.
÷=: (Division)
x=: (Multiplication)
Q: (Sum of quotients) Computes the division and accumulates the result.
P: (Sum of multiplications) Computes the multiplication and accumulates the result.
Constant: Constant multiplication and division.
R: (Remainder) Prints the remainder of the division.
Enter # x ÷: First factor entry key. Indicates the entry of the multiplicand or dividend.
Logic comments: This calculator is similar to the Logos 270. It has three working registers used during operations and also three independent registers or memories to store independent results. The basic operations are: Add, Subtract, Multiply, Divide, Square, Square root and percent.
Size: 18.9 x 15 x 10.6 in, 480 x 380 x 270 mm. Weight: 50 lbs, 24 kg.
Condition: (8/10) Very Good, imperceptible marks on casing. A minimum yellowing on the first generation ABS plastic cover. The interior of the machine is complete, just there is a broken blade of the motor fan. I never powered up the machine because I have no technical knowledge to try to test it.
Some magazine and newspaper ads of the Logos 328 I found on the web, click on the thumbnail.



Pictures of my Logos 328.


Inside of my Logos 328.


Pictures taken with


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