Monday, November 15, 2021

Retro Review: Canon F-73P

Retro Review: Canon F-73P

Quick Facts

Model: F-73P
Company: Canon
Years: 1982
Memory Register:  1 independent memory, 6 other memory registers; 1-6
Battery:  2 x LR44 or 2 x A76 batteries
Screen:  LCD, 10 digits
Logic:  AOS (Algebraic)
Programming Memory:  45 steps between 2 program slots

I want to give thanks to J N Jewelry and Watch Repair Center in Covina, CA for not only getting the calculator open but also to replace the batteries.   You rock!

Two ON-OFF Switches?

The Canon F-73P has two ON-OFF switches:  one as a mechanical switch on the top left corner of the calculator, and the regular OFF and ON/C buttons.

The switch turns on and off the permanent memory, which the manual referred as to the power switch.   When the power switch is off, all the calculator's memory is cleared.   

The ON/C and OFF turns the calculator's screen on and off.   Using the keys does not affect the calculator's memory.   


The Canon F-73P calculator is a scientific calculator with the following modes:

*  Hyperbolic functions
*  Base Conversions:  Decimal, Hexadecimal, and Octal  (no binary)
*  Single Variable Statistics
*  Linear Regression Statistics (y = a ∙ x + b)
*  Programming
*  Metric/US Conversions

RV Function: The RV function ( [ INV ] [ M+ ] ) reverse the operands in arithmetic operations.  The manual says it is for multiplication and division, but it works for addition, subtraction, power (a^x), and roots (x√) as well.   

Conversions:  A button  [ → ] ( ← ) is dedicated to four sets of U.S.-metric conversions.  Note that this the bold right arrow key, located above the [ STO ] key on the right side of the calculator.  

[ + ]:   gallons < - > liters
[ - ] :   Temperature: °F < - > °C
[ × ]:  lb < - > kg
[ ÷ ]:  in < - > cm

Even though the calculator can have a bigger set of conversions, understandably, it would clutter the keyboard.   Grateful to have these conversions built in.


The F-73P has two programming slots that can contain up to 45 steps.  Unfortunately, the programming is "blind", with out a way to view or edit programs.   This means that extra care, planning, and testing may be required.   

Entering programming mode, Mode 0 for Learn Program 0 and Mode 1 for Learn Program 1 will clear all the previous steps

Like the Casio fx-3600P and Radio Shack EC-4004, there are the ENT and HLT commands:

ENT:  Entry command.   In programming mode, the ENT enters a prompt.  You are then required to enter a dummy value (not counted as a step) before continuing with entering commands.  In program mode, just pressing the [ → ] (hollow key on the top row) will enter the ENT command.   

Entering a program is not only entering the commands but running a test case at the same time.  

HLT:  Halt.  Stops program execution and shows the display.   

What separates the F-73P from the simple programming calculators of the 1980's are the test and loop commands.  Instead of just sending the program back to start, the loop commands can send the point forwards or backwards up to 9 steps.  

x > 0 n:   Tests to see if the number is greater than zero.  If true, then skip n (-9 to 9) steps.  Else, go on to the next step.

x ≤ M n:  Tests to see if the number is less than or equal to the value stored in the independent register M.   If true, then skip n steps.  Else, go to the next step.  

GOTO n:  Skip n steps.

To help, the F-73P has partially merged steps.  The following count as one step:   

INV + command
HYP + command
x > 0 + command
x ≤ M + command
Conversion key + command

All programs are run in Decimal Mode (Mode 1).  [ RUN ] starts program 1 while [ INV ] [ RUN ] starts program 2.

[ RUN ] is then used for answering prompts and continuing execution.

I wish that these programming calculators would allow for editing or at least viewing.

Example Program:

f(x) =  x^2 if x ≤ 0; else √x

1:  ENT   (dummy value, say 1)
2:  x > 0  2     (if x>0 skip 2 steps forward)
3:  x^2
4:  GOTO 2   (skip 1 step forward)
5:  INV √
6:  HLT

I have not figured out how to use the skip command steps for more involved algorithms such as the quadratic equations.


The F-73P is a good calculator with your standard features.  The programming module is good for simple algorithms.  I like the eight conversions and base conversions.  


Toth, Viktor T.   "Canon F-73P"   R/S Programmable Calculators.  Accessed October 23, 2021.  

All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.

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