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Calculators: Handheld: Radio Shack Astro (EC-312)

(c) Emil Dudek 2010

Size (approx): 60-75mm x 120mm x 25mm  (w,h,d)
Weight 104g excluding batteries


3.0V DC, 300mW, 2 x AA size batteries. It does not accept an adaptor. 
Case: Ground-breaking shape to allow for the circular display filter.  Two piece matt black plastic case with a full front brushed aluminium panel.  Black printed key labels.  An oversized (and convex) blue tinted display filter is painted white with various guides.  The on/off switch is on the left hand side, about half way up.
Display: 8 digit blue VFD display with a ninth digit for negative and error signs. Also has four green and four yellow discrete LEDs as "astro indicators".
Features: Standard four functions only in calculator mode.  See below for further description of astro functions.
Age: 1979
Manufacturer: Radio Shack, A Division of Tandy Corporation. EC-312 Cat. No. 65-801. Custom manufactured in Taiwan for Radio Shack.  RS Cat No. 23-552, Serial number (inside battery compartment) No. 066788 5A1.


A fabulous calculator that should be in everyone's collection!  It is actually a branded version of the Kosmos Astro calculator, one of at least three different models they made.  Very basic calculator that is riddled with errors and shaky logic - why did they even bother?  There is an extensive instruction panel on the back - which is essential if you do not have the manual.  The original case is soft blue plastic in the shape of the calculator with an open top.

Construction: Whilst the case has two "lever points" I think there is a screw under the back info panel which I am not willing to damage to open this calculator.  Can any one verify this?

Logic comments: The (C) key operates as a cancel entry function on the first press whilst a second press will clear the calculator
Input overflow is suppressed, inputting a ninth digit is ignored
Negative numbers are shown with a "-" in the far left (ninth) digit thereby allowing full eight digit negative numbers 
There is no constant function
Divide by zero just results in zero with no error
Overflow displays the result and "E" in the ninth (far left) digit with zero as the result and is not recoverable
The astro functions invoke a pyrotechnic display of flashing digits for over ten seconds.
The astro functions consist of: Personal Astrological Information, Compatibility of two people, In-depth Compatibility analysis, daily horoscope, In-depth analysis of daily trends and daily horoscope questionnaire - wow!

Astro box

The highly colourful box on the left measures 100mm x 160mm and is 45mm deep and holds the polystyrene former snugly.  It is printed in blue, red and black.  I have seen images on the web with a 4A1 sticker on instead of this one's 5A1, probably a revision number.

Astro manual

This extensive manual measures 95mm x 134mm and is printed in black throughout with a black and olive green cover.  It has 56 pages, most of the first half is devoted to the astro functions whilst the whole second half talks about astrology.

Ref No.  6A0, printed in Taiwan.

Example Function: Astro Info
1) Switch on
2) Switch to Astro
3) Enter Birth-date (M=1-12, D=01-31, Y=00-99)
4) Press B1
5) Enter today's date as (3)
6 Read the Sun, Mercy , Venus, Mars results and compare them with the charts in the book.

Read Code S M V M

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