Spotlight: HP 16C Collector’s Edition

 Spotlight: HP 16C Collector’s Edition

Quick Facts: HP 16C Collector’s Edition

Model: HP 16C Collector’s Edition

Company: Hewlett Packard/Moravia

Type: RPN and Computer Science

Batteries: 2 x CR2032

Memory: Up to 34 memory registers

Programming Memory: Up to 203 memory registers

Years in Production:

Original: 1982-1989

Collector’s Edition: 2026 (limited edition)

Display: 8 digits (scrolling)

Store sites:

Europe: https://www.thecalculatorstore.com/i/the-hp16c

U.S.: https://shop.moravia.education/us/hp-16c-collector-s-edition.html

About the HP 16C

This is my first HP 16C from Hewlett Packard, and it’s a long awaited purchase. The HP 16C is a programmable calculator that is specialized in computer science. There are five main modes:

HEX: Hexadecimal integer mode (base 16, 2^4)

DEC: Decimal integer mode (base 10)

OCT: Octal integer mode (base 8, 2^3)

BIN: Binary integer mode (base 2)

FLOAT: Floating decimal mode.

The FLOAT mode is the only mode where calculations can involved fractions and non-integers. To make room for the Boolean logic and bit functions, the number of functions for floating point are limited to the reciprocal (1/x) and square root (√x).

The other four modes work with integers. The HP 16C is able to work with integers with up word sizes up to 64 bits. Each bit is is a binary bit. For example, a word size of 4 binary integers range from 0000 and 1111. Pressing [ 0 ] [ f ] [ STO ] (WSIZE) is a quick reset to a word size of 64 bits.

Integers can scroll beyond the initial screen of 8 digits, with multiple windows to show all the digits.

We have the classical Boolean functions available: AND, OR, NOT, and XOR. Part of what makes the HP 16C special is addition of bit manipulation functions:

* Shift bits left and right, including the carry over bit: SL, SR

* Arithmetic shift right, where bits are shifted right with the sign bit copied: ASR

* Rotate bits left and right: RL, RR, RL n, RR n (either a single bit or n bits); RLC, RRC, RLC n, RRC n (these are rotation functions including the carry over bit).

* Masks can be generated using the MASKL and MASKR functions.

* Integer division can be accomplished by finding the quotient (÷) and remainder (RMD).

* Finally, the HP 16C can work with double-sized words, potentially after 128 bits, with the double-multiply (DBL×), double-division (DBL÷), and double-remainder (DBLR).

The programming module can hold up to 203 steps, complete with loops, indirect addressing, testing, but no storage or recall arithmetic. Here are a couple of programs:

Integer Division: y |- x

Input Stack:
Y: dividend

X: divisor

Result: quotient, R/S, remainder

Code:

LBL D ; 001 43, 22, d

x<>y ; 002 34

STO 0 ; 003 44, 0

x<>y ; 004 34

÷ ; 005 10

R/S ; 006 31

RCL 0 ; 007 45, 0

LST x ; 008 43, 36

RMD ; 009 42, 9

RTN ; 010 43, 21

Examples

Example 1: 45 d |- 20 d = 2 d remainder 11 d

Keystrokes: DEC 45 ENTER 17 GSB D

Results: 2 d R/S 11 d

Example 2: 1F3 h |- 20 h = F h remainder 13 h

Keystrokes: HEX 1F3 ENTER 20 GSB D

Results: F h R/S 13 h

Hexadecimal: Showing One Hexadecimal Digit at a Time, From Right to Left

This program creates and then manipulates the mask to display each digit.

_ _ _ #

_ _ # 0

_ # 0 0

# 0 0 0

Code:

LBL A ; 001 43, 22, A

STO 0 ; 002 44, 0

CL x ; 003 43, 35

WSIZE ; 004 42, 44

HEX ; 005 23

F ; 006 F

ENTER ; 007 36

1 ; 008 1

+ ; 009 40

WSIZE ; 010 42, 44

RCL 0 ; 011 45, 0

4 ; 012 4

MASK4 ; 013 42, 8

AND ; 014 42, 40

R/S ; 015 31

3 ; 016 3

STO I ; 017 44, 32

LBL 0 ; 018 43, 22, 0

LST x ; 019 43, 36

4 ; 020 4

RL n ; 021 42 E

RCL 0 ; 022 45, 0

x<>y ; 023 34

AND ; 024 42, 20

R/S ; 025 31

DSZ ; 026 43, 23

GTO 0 ; 027 22, 0

RTN ; 028 43, 21

Examples

4F37 h GSB A: 1 R/S 20 R/S 400 R/S 5000

17695 d GSB A: F R/S 10 R/S 500 R/S 4000 (451F h)

The speed of the HP 16C Collector’s Edition is comparable to the HP 15C Collector’s Edition. I found the keys to be responsive and reliable.

Eddie

Sources:

“HP-16C” The Museum of HP Calculators. https://www.hpmuseum.org/hp16.htm Retrieved August 17, 2026.

Hewlett Packard. HP 16c Collector’s Edition: Owner’s Handbook. Edition 2, November 2025. From the HP Calculator Literature website: https://literature.hpcalc.org/items/2714

Eddie

All original content copyright, © 2011-2026. 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.

Spotlight: Casio fx-3650PII and Comparison with the fx-3650P and fx-50FH (II)

 Spotlight: Casio fx-3650PII and Comparison with the fx-3650P and fx-50FH (II)

Quick Facts: fx-3650P II

Model: fx-3650P II

Company: Casio

Type: Solar Scientific Algebraic, Programmable with battery backup: 1 x LR44/AP76

Memory: 7 memory registers: A, B, C, D, X, Y, M (M has memory addition and subtraction)

Programming Memory: 390 bytes, 4 program slots

Years in Production: 2013 (per fx-3650PII manual) to Present

Primary Market: Asia

Display: 10 digits

Casio’s fx-3650PII web page: https://www.casio.com/intl/scientific-calculators/product.FX-3650PII/

The fx-3650P II is the successor to the fx-3650P. The interface, menu structure, and the display of the fx-3650PII match that of Casio’s other current dual-powered programmable, the fx-50FH series (current as this blog entry fx-50FHII).

The modes available for the fx-3650 PII are:

COMP: This is our main calculator mode, with all the scientific functions available.

CMPLX: Complex Number mode: features complex arithmetic, conjugate, modulus (Abs), argument, rectangular/polar conversions.

BASE: Base conversions of integers between the four well known bases: binary, decimal, octal, and hexadecimal. The mode contains the standard Boolean operations.

SD: Single variable statistics (formerly named standard deviation mode)

REG: Regressions/two-variable statistics. A is usually the y-intercept and B is the slope.

The regressions available are:

Linear: y = a + b * x

Logarithmic: y = a + b * ln x

e-Exponential: y = a * e^(b* x)

Power: y = a * x^b

Inverse: y = a + b / x

Quadratic: y = a + b * x + c * x^2

ab-Exponential: y = a * b^x

Casio fx-3650P vs Casio fx-3650P II

Both of these calculators are (or were) sold primarily in Asia.  They are dual-powered: solar with a backup battery.  

Casio fx-3650P

*  Years Released: 2002 – about 2013

*  Pressing [ e^x ] types e. e(n) takes e^n not e × n.

*  Program space: 4 programs, total of 360 bytes

*  Absolute value function (Abs) is available in complex number mode (CMPLX) mode only.

The [ MODE ] key:  

Page 1: 1: COMP, 2: CMPLX

Page 2: 1: SD, 2: REG, 3: BASE

Page 3: 1: PRGM, 2: RUN, 3: PCL

Page 4: 1: Deg, 2: Rad, 3: Grad

Page 5: 1: Fix, 2: Sci, 3: Norm

Page 6: 1: Disp (display setup, fractions, rectangular/polar in complex mode)

CMPLX (complex numbers, primarily complex number arithmetic)

SD (single-derivation mode, single-variable statistics)

REG (regression mode, two-variable statistics)

BASE (base conversions and Boolean logic)

Program Functions (P-CMD), which is a limited set:

Page 1: ? (prompt), → (store), : (separator), ◢ (output/pause)

Page 2: ⇒ (jump/if-then-else), =, ≠, >, ≥

Page 3: Goto, Lbl

To exit program editing mode, press [ MODE ], [ MODE ], select 2 for RUN

fx-3650 PII

*  Production: 2013 – current? (not in United States, but in Asia)

*  Pressing [ e^x ] types e^(. This is gives a clear indication that we are using a function (exponential).

*  Program space: 4 programs, total of 390 bytes

*  Absolute value function (Abs) is available in all modes.

The [ MODE ] key: 

Page 1: 1: COMP, 2: CMPLX, 3: BASE

Page 2: 4: SD, 5: REG, 6: PRGM

CMPLX (complex numbers, primarily complex number arithmetic)

SD (single-derivation mode, single-variable statistics)

REG (regression mode, two-variable statistics)

BASE (base conversions and Boolean logic)

The SET UP menu, use arrows to navigate:

Page 1, Angles: 1: Deg; 2: Rad; 3: Gra

Page 2, Fraction: 1: a b/c; 2: d/c

Page 3, Complex Number: 1: a+bi; 2: r∠Θ

Page 4, Statistical Frequency: 1: FreqOn; 2: FreqOff

Page 5, Contrast Setting

Operating structure has adopted the structure of the fx-50FH (a past model, it’s since been updated to the fx-50FHII).

Program Commands (P-CMD), available on both the fx-3650PII and fx-50FH series:

Page 1: ? (prompt), → (store), : (separator), ◢ (output/pause)

Page 2: ⇒ (jump/if-then-else), =, ≠

Page 3: >, <, ≥, ≤

Page 4: Goto, Lbl

Page 5: While, WhileEnd

Page 6: Next, Break

Page 7: For, To, Step

Page 8: Else, IfEnd

Page 9: If, Then

To exit program editing mode, press [ MODE ], [ MODE ], select 2 for RUN

When entering a new program, you are prompted to select the type of program at the start: COMP, CMPLX, SD, REG, or BASE.

Casio fx-3650 PII vs. Casio fx-50FH (II)

The main difference is that the fx-3650 PII has the numerical calculus functions integration and derivative, while the fx-50 FH has a library of scientific constants and 23 built in formulas. The fx-50FH has 680 bytes of programming memory.

The next post will have four programs that are done with both the fx-3650P and fx-3650P II to illustrate the programming differences.

Eddie

All original content copyright, © 2011-2026. 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.

Spotlight: Casio fx-451 Calculator

Spotlight: Casio fx-451 Calculator

Quick Facts

Model: fx-451

Company: Casio

Type: Solar Scientific Algebraic

Memory: 1 (store, recall, exchange (X←→M), sum (M+), subtract (M-))

Years in Production: 1985 to 1987 per calculator.org (https://www.calculator.org/calculators/Casio_fx-451.html)

Display: 10 digits

Casio Ledudu’s page on the fx-451: https://casio.ledudu.com/pockets.asp?lg=eng&type=1016

Folding Calculator Power

The Casio fx-451 is a folding scientific calculator. On the left side, there are the arithmetic keys, the shift, mode, and on keys, the display (10 digits), and the solar panel that operates the calculator. The right side has touch, rubber-like, membrane keys. The right side has all the scientific, statistical, fraction, base conversion, and imperial/metric conversions.

You can see my review of the fx-450 from 2018 here: https://edspi31415.blogspot.com/2018/07/retro-review-casio-fx-450-calculator.html

The available modes for the fx-451 are:

. (decimal point): SD (Standard Deviation), single variable statistics. Statistics functions are marked in blue.

0: DEC. Decimal mode. This is also the calculator’s normal/computation mode.

1: BIN. Binary integer mode (base 2). Boolean logic operators are available and are marked in green.

2: OCT. Octal integer mode (base 8). Boolean logic operators are available and are marked in green.

3: HEX. Hexadecimal integer mode (base 16). Boolean logic operators and the letter digits A-F (A=10 to F=15), are available and are marked in green.

4: DEG. Degree angle mode.

5: RAD: Radians angle mode.

6: GRA: Gradians angle mode.

7: FIX: Fixed point decimal setting

8: SCI: Scientific notion decimal setting.

9: NORM: Floating point decimal setting. Numbers less than 0.01 are shown in scientific notation form.

The engineering keys, [ENG] and [←ENG], temporarily show the number in display using scientific notation where the exponents are in multiples of 3 (i.e. 10^-6, 10^-3, 10^0, 10^3, 10^6, etc.)

Like many Casio scientific calculators, the fx-451 sports the fraction key [a b/c], allowing both entry of fractions (proper and mixed), and conversions between fractions and decimal approximations.

In addition, the fx-451 has nine scientific constants. (by pressing [SHIFT] [1-9]).  The constants are:

1. Speed of Light (c)

2. Plank’s constant (h)

3. Universal gravitational constant (G)

4. Electron charge (e)

5. Mass of an electron (me)

6. Atomic mass constant (u)

7. Avogadro’s constant (Na)

8. Boltzmann constant (k)

9. Molar volume of ideal gas (Vm)

All units are in SI units, and are listed with the constant on the keyboard.

The fx-451 Adds Imperial/Metric Conversions

(fx-450 (top), fx-451 (bottom))

The fx-451 is a later version of the fx-450 and has added a set of eight imperial/metric conversions:

Temperature: degrees Fahrenheit/Celsius

Length: inches/millimeters

Volume: gallons/liters, ounces/grams

Mass: pounds/kilograms

Energy: calories/Joules

Pressure: inches of Mercury/kilopascals, atm/megapascals

Conversions are called by the two arrow keys [ ← ] and [ → ], and are they are marked in gold. I always find conversions to be a welcome addition to any calculator.

Solar Power

Like it’s cousin, the fx-450, the fx-451 operates only by solar and light power, hence no other batteries are required.

This is a fun calculator to have, and Casio does a really good job of including lots of features even in its basic scientific calculators.

Eddie

All original content copyright, © 2011-2026. 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.

Spotlight: Calculated Industries Gradematic 100

Spotlight: Calculated Industries Gradematic 100

Quick Facts

Model: Gradematic 100

Company: Calculated Industries

Timeline: 1983

Type: Grades conversion, Four Function

Power: 2 LR44/AR76 batteries

Number of Functions: 576 (see source)

Calculated Industries has three sequels to the Gradematic 100: Gradematic 200, Gradematic 3000, and Gradematic 4000.

Get that Grade!

The Gradematic 100 has four main modes:

* Four Function Calculator

* Timer

* Numerical Grades

* Letter Grades

Four Function Calculator (Calculate Mode)

The four function calculator is the basic calculator with the four arithmetic functions (+, -, ×, and ÷), the percent function (%), and one memory register. The [ MRC ] key acts as both a memory recall and clear. However, there is no square root or change sign key.

From any other mode, we can enter the Calculate mode by pressing the equals key [ = ].

Timer Mode

The timer has the ability to count down from a set time or count up (stopwatch).

Count Down: [ TIMER ], enter minute and seconds, then press [ TIMER ] again. The Gradematic 100 does not beep when the timer runs out.

Count Up: With the display at 0 minutes and 0 seconds, press [ TIMER ] starts the stopwatch. Press [ TIMER ] again to stop the time. The stopwatch can only be stopped once.

Numerical Grades Mode

In the Numerical Grades mode, we can enter numerical grades for students depending on the total number of assignments and tests. The general process is this:

1. Press the [ NUMERICAL GRADES ] key.

2. Enter the maximum total score, which would get the student an A+ grade, then press [ STORE*HI ].

3. Enter the minimum total score of which a student to earn a D- grade, then press [ STORE*LO ].

4. To see the break down, press the [ BREAK POINT ] key repeatedly. When ready, press the [ CONTINUE ] key.

5. For each student, enter each grade, then press the plus button [ + ]. When finished, press the [ STUDENT AVERAGE ] key get the average and the grade.

6. (Optional) Repeat step 5 to enter additional students. Press the [ MRC ] key to get the Class Average.

Example: In a class of six assignments worth 100 points each (for a total of 600 points), find a students’ average on the grades: 88, 78, 85, 92, 93, 90. The minimum grade for a D- is 60% of the maximum (360 points).

[ NUMERICAL GRADES ]

Display: E Hi Sc. 600 [ STORE*HI ]

Display: E Lo Sc. 360 [ STORE*LO]

Display: b.P. Press [ BREAK POINT ]:

360 d-

380 d

400 d+

420 C-

440 C

460 C+

480 b-

500 b

520 b+

540 A-

560 A

580 A+ (press [ BREAK POINT ] to repeat the cycle)

[ CONTINUE ] Display: Su Sd Gr

88 [ + ] 78 [ + ] 85 [ + ] 92 [ + ] 93 [ + ] 90 [ + ] Display: 6 526 (total points: 526)

[ STUDENT AVERAGE ] 6 3.26 b+

Note: For some reason, the grade below D is labeled E.

Letter Grades Mode

The Letter Grades mode operates in a similar way to the Numerical Grades Mode. The Letter Grades Mode has specialty keys [ A+ ] through [ E ]. The student average and class averages works the same way.

Example: Find a students average consisting of the grades A-, B, C+, B+, A-, A.

[ LETTER GRADES ]

Display: Ent Gr. [ A- ] [ B ] [ C+ ] [ B+ ] [ A- ] [ A ] [ STUDENT AVERAGE ]

Display: 6 3.33 b+ (average 3.33 B+)

Two Scales

The GradeMatic 100 has two GPA scales: one where A is worth 4 GPA points, and A is worth 12 GPA points. This scales can be toggled with [ A=12 ] key, which can be pressed at any time.

Final Thoughts

If you get a Gradematic 100, make sure that a manual is included. I purchased one from a local thrift mart for a $1.00 but there was no instructions. That led me to purchase another Gradematic 100 on eBay.

Another fine specialized calculator that was once made by Calculated Industries.

Eddie

All original content copyright, © 2011-2025. 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.

Quick Review: Casio fx-9910CW 2nd Edition

Quick Review: Casio fx-9910CW 2^nd Edition

The Casio fx-9910CW 2^nd Edition is an update of the fx-991CW first released in 2023.

Product Pages

United States:

https://www.casio.com/us/scientific-calculators/product.FX-9910CW/

The fx-9910CW has two keyboards: black with gold font and pink with purple font (limited). I have one each and Casio has improved on the readability on the pink edition with the dark purple font.

I’m sure this model will be available world wide soon.

What’s the Same and What’s Different

Overall, the fx-9910CW 2^nd Edition has the same mathematical features as the fx-991CW. The modes included are:

Calculate: the main app for mathematical calculations

Statistics: 1 and 2 variable with seven regression models:

Linear:  y=a+bx

Quadratic: y=a+bx+cx^2

Logarithmic:  y=a+b*ln(x)

Exponential:  y=a*e^(bx)

Power I:  y=a*b^x

Power II: y=a*x^b

Inverse:  y=a+b/x

Statistical graphs may be generated with the QR feature.

Distribution: Binomial, Normal, and Poisson distributions, along with their inverses. The functions work with lower-tail probabilities (-∞ or 0 to x).

Spreadsheet: 5 columns, 45 rows. 2,380 byte memory.

Table: Generate a table for up to two functions f(x) and g(x). Generate graphs with the QR feature.

Equations: Linear systems (up to 4 x 4), polynomials up to 4^th order, and a general equation solver.

Inequalities: Solve inequalities for polynomials up to the 4^th order.

Complex Numbers: Complex number arithmetic with polar/rectangular conversion, integer powers, real/imaginary parts, conjugate

Base N: Base mode for the traditional decimal, hexadecimal, octal, and binary basis. Binary integers are up to 31 bytes with one sign bit.

Matrix: Four matrices, up to size 4 x 4, with basic matrix functions such as determinant, transpose, and inverse.

Vector: Four vectors, 2D or 3D, with dot product, cross product, and norm.

Math Box: Dice Roll and Coin Toss simulations

47 scientific constants (SI units) and unit conversions

We still have the newer Casio style of navigation keys, the Home Key, the Back Key, the Settings key, and the Scroll up and down keys.

What is different?

First, the fx-9910CW is not solar powered, but instead runs on a single AAA battery.

Welcome changes:

The menus all have short cut keys! This eliminates the requirement to scroll down menus, which some get long, to find the sub menus and functions. This makes the operating the calculator a lot easier and more efficient, eliminating additional key strokes by repeatedly pressing the arrow keys.

For example, to get the absolute value in Calculate mode, press [ CATALOG ], [ 3 ] for Numeric Calc, [ 1 ] for Absolute Value.

In the same mode, we call up the Speed of Light constant (c), press [ CATALOG ] , [ 7 ] for Sci Constants, [ 1 ] for Universal, and [ 3 ] for c.

There is a setting to turn the hide the shortcut numbers but thankfully it won’t turn off the ability to navigate by using short cut keys.

The 10^[] and FORMAT keys return to familiar form! Like the fx-CG 100, we have an option on how the 10^[] and FORMAT keys operate.

10^[] Key:

(1) Power: Acts like a power key like the fx-991CW. I read that there are potential problems with calculating with this key leaving calculations to return unexpected answers.

(2) Sci. Notat: This returns this key to the traditional scientific notation key. When this option is selected, the 10^ is shown in a small font. This key now acts like the [ EE ] or [ EXP ] keys on other scientific calculators. This is the default setting.

FORMAT Key:

(1) -π√ ←→ Decimal. Pressing the FORMAT key just toggles between decimal and the exact (when available) format of answers. This brings back the beloved [ S←→D ] key. This is the default settings.

(2) Format Menu. This is the format menu that is presented, similar to the fx-991CW. We trade off the quick toggle for additional formatting options.

Shortcut Catalog. Pressing [ SHIFT ] [ CATALOG ] is a new feature and provides a listing of all mathematical functions available in the active mode. Up to 15 functions are shown, using the arithmetic keys (+, -, ×, ÷) and the decimal point (.) as additional shortcut keys. The shortcut catalog does not have the conversions or constants.

These changes are welcome and enhance the operating experience of the calculator.

My next wish is that the fx-9910CW included the Algo mode (algorithm mode) that allowed small programs (via a mix of Scratch and Casio Basic). You can find out more details here:

https://edspi31415.blogspot.com/2025/08/casio-fx-92-college-plotting-lines.html

I just think the algorithm mode is neat, gives students an introduction to programming, and would have fit the fx-9910CW well.

Great job, Casio. I think Casio listened to calculator users and brought back these improvements, and brought it more in line with operating the fx-CG 100/Graph Math Plus. If you were hesitant about the fx-991CW, the fx-9910CW 2^nd Edition is a good time to jump in.

Eddie

All original content copyright, © 2011-2025. 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.