NonHP RPN
(Reverse Polish Notation) Calculators 

Sinclair Scientific.
Introduced
in 1974, One of Sinclair's two
RPN calculators. Hewlett Packard had introduced the HP 35
with advanced scientific functions at that time, but at a
very high price. Of course, the HP was of superb quality,
while the Sinclair was fragile.
Original price: £32.50 built, or £19.95 as a
kit. 

Sinclair Scientific Programmable.
Introduced
in 1975, this was British
Sinclair's answer to programmable calculators. The price was
low, but so was the functionality. The reason this
calculator made it to this collection, is because it used
RPN.
Original price: £25 

Commodore Minuteman 6X.
This is a plain fourfunction calculator manufactured by
Commodore in 1973. However, it is the only Commodore calculator that
was manufactured with RPN logic. Commodore also manufactured
the exact same calculator as the Minuteman 6 (not 6X) with
algebraic notation. 

Calfax 616.
I cannot locate any information on this calculator other
than that Calfax was a division of American Imports Merchant
Corporation and most likely manufactured in Hong Kong in the
mid70s. It remains interesting as another example of an RPN
calculator however. It also sold under the label Supercal
616. 

Omron 12SR.
Manufactured by Omron Tateisi Electronics of Japan, they had
colorful buttons and displays. The 12SR, also known as "the
slide rule," is the only RPN calculator Omron manufactured.
It has a green fluorescent display with all the standard
scientific functions. 

National Semiconductor 4520
Scientist.
An RPN calculator manufactured by National
Semiconductor, USA, which also sold calculators under the
Novus name (see below).


National Semiconductor 4525
Scientist PR. Another RPN
calculator manufactured by National Semiconductor, this one
a programmable one.


National Semiconductor 4640.
Another RPN calculator manufactured by National
Semiconductor.


National Semiconductor 4615 PR.
Also an RPN calculator manufactured by National
Semiconductor in Malaysia in the 1970s. Identical to the
Novus Mathematician PR. It is a scientific programmable
calculator with 102 steps.


National Semiconductor 600.
Introduced by late 1973, this is a simple RPN calculator,
however without an ENTER key. The "+" key is used in place
of ENTER to separate numbers.
Original price: $19.95 

Novus 650 "Mathbox".
Introduced in 1974 by National
Semiconductors, it could do the basic four arithmetic
operations. It is of great interest however, as it like
Hewlett Packard, was using the RPN notation, instead of the
common algebraic notation found in most calculators.
Original price: $17 

Montgomery Ward P10.
This is a Novus 650 "Mathbox" (see above), but with the
Montgomery Ward brand on it. It is functionally equivalent
to the 650. 

Novus 4510 Mathematician.
Also known as the Novus 4510 or the National Semiconductor
Mathematician, it was a National Semiconductor calculator
branded as Novus to help them promote their calculators.
Like the Hewlett Packard calculator,
it uses the
RPN (Reverse Polish Notation) method to perform calculations.
It was introduced in 1975 and was manufactured in Malaysia.
Original price: $60 

Novus 4515 Mathematician PR.
Another National Semiconductor RPN calculator, also known as
the NS 4515. This one, however, has a 3level stack and it
is programmable. 

Privileg SR54NC.
A scientific RPN calculator made by Quelle International, W.
Germany. It basically has the same engine as the Omron 12SR
(notice the "SR" notation on both).


APF Mark 55.
APF Electronics Inc., a New York city based calculator
manufacturer, had most of their models built in Japan. Mark
55, built in 1977, was the only APF with RPN logic. It included, like the HP, a 4level stack named x, y, z and w, 9 memories and the
basic scientific and statistical functions, along with some
unit conversions.
Original Price: $60 

Elektronika B319M.
The first Soviet Elektronika RPN calculator manufactured in
1976. Included basic scientific functions in a very robust
case, but with keys that were light to the touch and could
very easily produce erroneous entries.
Original price: 240 rubles 

Elektronika B321 (LED).
One of the first Soviet Elektronika calculators, the
production of which started in 1977 and ended in 1981. It
was an RPN calculator, programmable with 60 steps. The early
version used red LEDs.
Original price: 350 rubles 

Elektronika B321 (VFD).
This is the second version of the B321 that used a green
VFD display. It has otherwise the same functionality of the
original model, but was offered at a reduced price.
Original price: 190 rubles 

Elektronika B334.
A Soviet RPN calculator, the production of which started in
19781979. A very popular calculator, it included scientific
functions, 98 program steps and
indirect addressing. It also used a green VFD display like
the B321. This design was later changed to create
the MK54 (see below).
Original price: 80 rubles 

Elektronika MK54.
A Soviet RPN calculator, most likely the first one in the
series of MK calculators. Production started in 1982 and
stopped in 1985, possibly because the more powerful MK61
was in the mean time released.
Original price: 65 rubles 

Elektronika MK52.
This calculator was made in Russia between the years 1983
and 1991. A true RPN and programmable calculator with 105
steps and 15 memories. It was the only calculator in the
world to use EEPROM (512 steps) for internal storage of data
and programs. It had a Cyrillic keyboard.
Original price: 115 rubles 

Elektronika MK61.
One of the most powerful (nonBASIC) Soviet calculators ever
manufactured, it also had a Cyrillic keyboard and was also
an RPN calculator. It is identical to the MK54, but the
MK61 is programmable capable of accommodating 105 steps and
15 registers. Production started in 1983 and finally
stopped in 1993.
Original price: 85 rubles 