Sperry Remington 663

Sperry Remington 663
Sperry Remington 663

In 1973, pocket calculators were still expensive devices which were not affordable to the broad masses. A part of the costs were caused by the displays, that were penny goods that time. Born from necessity, many ideas came up to reduce the production and selling costs and to increase the sales figures.

One of these solutions was, to reduce the display costs by showing only six instead of the familiar eight (plus one for negative numbers/error) digits. The missing digits should be displayed by pressing a special key.

One of the providers of that rather weird idea was Sperry Remingtion, who launched in 1973 the model 663 with six individual display tubes and a simple equipment.

At that time, these kind of calculators were by all means successful; today, after more than 30 years, these antiques appear really weird and might not be used anywhere anymore.

Case and Keyboard

back view
back view

On the Sperry Remingtin 663, you will remark two things, when you hold it in your hands: Its great weight and its enormous height. According to this, the case is constructed in a very stable manner. It consists of two plastic halves, which are fixated together and secured with a single screw.

The upper half of the top case contains the display below a slightly toned and angeled plastic pane. The rest is covered by an aluminium plate, which gives the calculator a very siginificant look.

The keyboard consists of only 18, pressure-point free keys, that have a rather long traveling way and work mostly bouncing-free. The most interesging key is the "->" key, which displays the six least significant digits, as long, as the key is pressed.

Construction

inside view
inside view

Since six display tubes and the technical state-of-the-art of 1973 demanded a rather complex construction, inside the 663 there are two PCBs (plus one keyboard module), which are connected by a row of wires:


there are two PCBs inside
there are two PCBs inside

As you can easily see, the construction requires a lot of external parts, as resistor arrays, many single resistors and capacitory, a driver IC and the other usual parts such as the high voltage transformer, six one-digit display tubes etc.

It's a real pleasure to see this, but it is also easily imaginable, that all that wasn't very cheap. Nevertheless, it raises the question, why the reduction of two display digits should result in a significantly lower price. Maybe, the answer can be seen, by looking at the display:

Display

display construction
display construction

The display consists of six VFD tubes of the type NEC LD8035E. Each of them is connected via 12 wires, among them eight for the eight segments (although the eigth segment, the rightmost part of the "4" is unused although connected), one for the decimal point, two for the filament and one for the fence.

This kind of technics with discrete tubes was already outdated in 1973 and there's not much fantasy needed to imaging, that the reduction of the wires to be solderes from 96 (eight digits) to 72 (six digits) can safe a lot of money, especially on (manual) mass assembly. Additionally, all tubes had to be aligned exactly, which is also a lot of work.

It was typical for Sperry Remington, that the digit "0" only uses the lower part of the display tube and thus looks very different than all other numbers, using the full height:


displaying of a zeri
displaying of a zeri

CPU

The Sperry Remington 663 uses a NEC µPD177C as CPU. Since that chip wasn't able to handle everything, another chip by NEC was used, a µPD129C.


detail foto: CPU
detail foto: CPU

Calculating Capabilities

Thanks to the reduced display capabilities and since the caluclator ICs were just at the beginning of their evolution, the calculating capabilities are pretty simple: Only the four standard calculations were possible and nothing else.

It uses the simple direct entry logics, which means, that all calculation steps are executed immideatly without intermediate storage. A calculation step is executed, when either one of the operations keys (+,-,* or /) or the equal sign was pressed and displays the result immideatly. With that result, you can go on calculating.

As soon, as the display limit (999999) is exceeded, the result can still be retrieved in full length with the arrow key, but you cannot use it for further calcuations.Interestingly, on the addition, the second key can have at max as many digits after the comma, as can be used in the display. This means, that to the value 999999, you can only add a value without any decimal places, to 99999 a value with at max one decimal place, to 9999 max. two decimal places and so on.
On the other hand, you can turn it and enter at first a number with all possible decimal places and then a six digit number. 3.33333 + 999999 can be calculated only this way round and gives the correct result (by using the arrow key) of 1000002.33333.

On the division, you can display up to ten decimal places, but only those, which are directly shown in the display will be used for further calculations. So, 1/7 at first results in 0.14285714285; if you multiply this by ten, the value changes to 1.4285000000. On the addition, the number of decimal places also goes down. 1/7 results again in 0.14285714285; if you add 1 to it, the result is 1.1428571. If you had added 10 instead, the result would have been 10.1428571. So, it looks, that on the addition, internally at max seven decimal places are used for the calculations.


1/7, first part
1/7, first part


1/7, second part
1/7, second part

The division by zero is correcly indicated by an error. In this case, the zero digit is displayed in all digits and also a dim decimal point everywhere:


error indication
error indication

The addition of 1 + 0.000 results in the incorrectly rounded value of 1.000, and the calculation of (-1) + 1 results in the incorrect negative zero (-0).

Summary

The Sperry Remington 663 is a fantastic weird and antique constructed "pocket" calculator, where you can see the dispute between great engineer work and cost-orientated production in a very nice way. It was between all fronts, when calculators had to be made available for everyone for any price.

No good collection should miss such a device!

Technical data

ManufacturerSperry Remington
Model663
Year1973
CPUNEC µPD177
Display6x1 digit VFD
Number of keys 18
Functions+ - * /
Entry logic (classificationALG (BGAA)
1 + 0.000 = 1.000 (the correct value would be 1.)
0 / 0 = Error
(-1)+1 = -0 (should have resulted in 0)
Power supply 4xAA
Power consumption 0.6 W
Size15.5 x 8.1 (8.4) x 4.1 cm
ConditionA-B
Factsheet


Links
mycalcdb: Sperry Remington 663 (en) 
Sperry Rand Calculators (by Guy Ball) (en) (A few notes about the history of Sperry Remington)
Vintage Technology: Sperry Remington 663 Type I (en) (Very informative description)