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 

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, pressurepoint free keys, that have a rather long
traveling way and work mostly bouncingfree. The most interesging key is the ">" key,
which displays the six least significant digits, as long, as the key is pressed.
Construction

inside view 

Since six display tubes and the technical stateoftheart 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 

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 onedigit 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 

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 

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 

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, 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 

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
costorientated 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
Manufacturer  Sperry Remington 
Model  663 
Year  1973 
CPU  NEC µPD177 
Display  6x1 digit VFD 
Number of keys  18 
Functions  +  * / 
Entry logic (classification)  ALG (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 
Size  15.5 x 8.1 (8.4) x 4.1 cm 
Condition  AB 

Factsheet 