** Retro Review: Casio fx-7500g**

**Quick Facts:**

**Folding Calculator Power**

**Special Announcement**

A blog is that is all about mathematics and calculators, two of my passions in life.

** Retro Review: Casio fx-7500g**

Model: fx-7500g

Company: Casio

Year Introduced: 1988, 1989

Batteries: 3 LR-44

Memory Registers: 26, but can be expanded

Program Steps: 4214 maximum, 10 program slots

Price: About $109.95 at introduction, various with collections

The Casio fx-7500g is an early graphing calculator that is modeled after the Casio fx-7000G, which features include:

* Basic scientific functions, including fractional and integer parts, factorial, absolute value

* Base Conversions and Boolean logic (not, and, or, xor)

* Single-valued statistics with a separate mode for bar graph, line graph, and normal distribution curve based on values (SD2)

* Linear Regression (a + bx) with a separate mode for plotting points and plotting the regression line (LR2)

* Random Numbers

* Programming, with allocation for 10 programs. The maximum amount of programming steps is 4,214 which can be allocated to additional memory registers.

The programming language of the fx-7500g is the same as the fx-7000g and fx-6300g, but a lot more programming space. The additional steps allowed programs to have comments and descriptive prompts without worry about running out of space. Why didn't Casio put more programming steps in either the fx-7000g or fx-6300g?

In 2012, I discussed the programming language and its commands here.

I am amazed how small the fx-7500g is, yet the screen is readable while graphs take the entire screen. The flat keys are very responsive and after a while the keys became comfortable to touch. I can see why the fx-7500g is a collectable.

I think Casio may be the only company with foldable graphing calculators: fx-7500g, it's financial cousin FC-1000 (which fetch high prices on auction sites), and the fx-9860g Slim.

Casio fx-7500g (left), Casio fx-9860g Slim (right)

This is a rare calculator to find, and if you can get it for a good price (I paid $45), it is worth collecting. By the way, handle with care as the case is fragile and the screen doesn't take drops too well. Thankfully it still works!

Programs for the Casio fx-7000G (fx-7500G, fx-6300G, and all of the other variants) every Saturday in June 2021. Please join me in this trip back to the 1980s.

Until next time,

Eddie

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.

**Numworks: Rotated Plot - Python **

The script rotplot.py allows the user to choose between one of five equations and rotate the graph at a given angle. The equations are:

1. y = a + bx

2. y = ax^2 + bx + c

3. y = ax^3 + bx^2 + cx + d

4. y = a * sin(bx + c) + d

5. y = a * exp(bx + c ) + d

The original plot is in gray, the rotated plot is in blue.

(Size: 1,500 bytes)

from math import *

from matplotlib.pyplot import *

# 2021-04-18 EWS

print("Choose an equation.")

# define a,b,c,d

a=0

b=0

c=0

d=0

eq=6

while eq<1 or eq>5:

print("y=")

print("1. ax+b")

print("2. quadratic")

print("3. cubic")

print("4. a sin(bx+c)+d")

print("5. a exp(bx+c)+d")

eq=int(input())

a=float(input("a? "))

b=float(input("b? "))

if eq>=2:

c=float(input("c? "))

if eq>=3:

d=float(input("d? "))

p=float(input("Angle in degrees? "))

p=radians(p)

# main routine

xa=float(input('start? '))

xb=float(input('stop? '))

n=float(input('n? '))

xc=(xb-xa)/n

# define function here

def f(eq,a,b,c,d,x,p):

if eq==1:

y=a*x+b

if eq==2:

y=a*x**2+b*x+c

if eq==3:

y=a*x**3+b*x**2+c*x+d

if eq==4:

y=a*sin(b*x+c)+d

if eq==5:

y=a*exp(b*x+c)+d

xr=x*cos(p)-y*sin(p)

yr=x*sin(p)+y*cos(p)

return [x,y,xr,yr]

# build

flist=f(eq,a,b,c,d,xa,p)

xlist=[flist[0]]

ylist=[flist[1]]

xrlist=[flist[2]]

yrlist=[flist[3]]

xp=xa

# lists

while xp<xb:

xp=xp+xc

flist=f(eq,a,b,c,d,xp,p)

xlist.append(flist[0])

ylist.append(flist[1])

xrlist.append(flist[2])

yrlist.append(flist[3])

# plot routine

# set axes

x1x=min(xlist)

x1xr=min(xrlist)

x1=min(x1x,x1xr)

y1x=min(ylist)

y1xr=min(yrlist)

y1=min(y1x,y1xr)

x2x=max(xlist)

x2xr=max(xrlist)

x2=max(x2x,x2xr)

y2x=max(ylist)

y2xr=max(yrlist)

y2=max(y2x,y2xr)

axis((x1,x2,y1,y2))

axis(True)

grid(True)

# plot points

plot(xlist,ylist,color='gray')

plot(xrlist,yrlist,color='blue')

show()

Download the script here: https://workshop.numworks.com/python/ews31415/rotplot

Eddie

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.

** Review: Canon DK-10i II Computer Keypad Calculator **

**Just The Facts**

Model: DK-10i II (successor to the DK-10i)

Production: 2007 - present (DK-10i and DK-10i II)

Power: Solar with battery backup, 1 x CR2016, USB when plugged into a computer

Price: Varies from $8.00 to $22.00 (be a smart shopper)

Operating System: Chain

**Functions**

Arithmetic: +, -, ×, ÷

Memory Keys: M+, M-, RCM (Recall/Clear Memory, CALC mode only)

Tax Functions: Tax Set, Tax Recall, Tax+, Tax- (CALC mode only)

Decimal Selection: Float, 0, 2, 3. Press [ AC ] then hold the [ . ] key until the mode changes. You can change one decimal rounding mode at a time.

However, the DK-10i II lacks both a square root key and a change sign key. I find this to be a miss. I don't know how many four-function and simple calculators still lack a square root key.

To start off a calculation with a negative number: enter 0 [ - ] number [ = ]. I think Canon was going for more of a keypad approach.

The calculator also has four arrow keys.

**A Calculator of Multiple Uses**

**CALC Mode:**

In CALC mode, the DK-10i II is a four-basic function calculator. The calculator is solar powered, while using a battery backup to store tax rate and memory. In CALC mode, the memory and tax keys are functional.

The DK-10i II works in CALC mode when connected to a computer by USB. Results can be forwarded to an appropriate app by the [SEND] key: Calculator, Excel, LibreOffice, most text applications, and spreadsheet applications.

**PC Mode:**

The PC Mode is where the DK-10i II shines. In PC mode, the DK-10i II acts a numeric keyboard. The nice part is that the arrow keys are separate from the numbers, saving us from toggling Num Lock. The percent key becomes a comma in PC mode.

Numbers and calculations works in spreadsheet, calculator, and text apps. So far I used it on my home Windows PC and a Microsoft Surface without problems.

**Verdict**

I wish the DK-10i II had a square root and change sign key. However, it makes for a great key pad which fulfills a need for smaller laptops including Chromebooks. For that reason, I would recommend looking into getting a portable key pad of this type, especially for those who work in business in remote settings.

Eddie

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.

**Firmware Update: Swiss Micros DM42 - DMCP 3.21/DM42-3.19, Free42, and Offscreen Images**

**Firmware Update**

Swiss Micros released a firmware update to the Swiss Micros DM42 calculator. The current versions are:

* DMCP 3.21

* DM42-3.19

Download the file here:

https://technical.swissmicros.com/dm42/firmware/

This firmware brings the DM42 in alignment with Firmware 3.0.3 of Free42 by Thomas Okken. Click here for details:

https://thomasokken.com/free42/history.html

Furthermore, you download the latest version of Free42 here:

https://thomasokken.com/free42/#doc

Steps:

1. Plug in the DM42 into the PC.

2. Activate USB Disk. Press [ shift ] [ 0 ] (SETUP), 1. File, 3. Activate USB Disk.

3. Transfer the file (see Tip below) to the root directory of the calculator (hardware).

4. Exit USB Disk on your calculator. The firmware should update itself automatically.

Detailed instructions and other ways to update firmware can be found here, refer to sections 6.2 for the quick update or 6.3 for an alternative method:

https://technical.swissmicros.com/dm42/doc/dm42_user_manual/#quick_update_guide

Tip: When transferring the bin file to the calculator, you want to transfer the combination bin file DCMP_flash_3.21_DM42-3.19.bin. You need both the DCMP and DM42 files for the calculator to run.

**New Comparison Functions**

X=?, X>?, X<?, X≤?, X≥?, X≠?

These tests compare the contents of the X Register to any other stack (T,Z,Y,L) or variable.

Example:

R01 = 33

X: 25

X>? 01 returns No (next program step will be skipped)

X<? 02 returns Yes (next program step will be executed)

0=?, 0>?, 0<?, 0≤?, 0≥?, 0≠?

These tests are similar to the above except this comparison of any target stack or variable to zero.

Both can be found in the CATALOG-PRGM menu. In CATALOG, scroll to the PRGM submenu.

**Writing Program Lines with X2LINE and A2LINE**

Found in the CATALOG-MISC menu, X2LINE and A2LINE creates a program line from the X-stack and Alpha register, respectively. This allows the user to create program lines outside of the program editor. I don't know how this can be effective when it comes to executing functions, but they are here.

**Enhanced VARMENU Command**

The VARMNU1 allows the user to select variables without having to assign values to other variables first. Found in the CATALOG-PRGM menu.

**Longer String Creation with XSTR**

I think this going to be my new favorite command besides the new comparison functions. The XSTR allows for creation of strings of any length, beating the six-character limit of ASTO. Found in the CATALOG-PRGM menu.

Example:

CLA

XSTR "FREE 42/DM 42"

ARCL ST X

XSTR " 2021"

ARCL ST X

Alpha Register: "FREE 42/DM42 2021"

**Off Images for the DM42 and DM41X**

Off images must be the size of 400 x 240 pixels and be 1-color (monochrome) .bmp files.

Carbon Canyon Park, Brea, CA - April 2021

Polar Butterfly - Plotted on an HP Prime - 2020

Mojave Narrows Park, Victorville, CA - May 2021

Laguna Beach, CA - March 2021

Eddie

**Numworks: Update to Software Version 15.5 **

On May 10, 2021 updated their software of the Numworks graphing calculator to Version 15.5.0.

**New Features**

Some of the new features include:

Calculation Mode:

* The Calculation mode gets a new section: Vectors. The available functions are dot, cross, and norm.

* The ref and rref functions are added to the Matrices section.

* When the results is a matrix, we can go up into the history, select the three dots next the matrix. This gives us the additional results: determinant*, inverse*, row echelon form, reduce row echelon form, and trace* (*for square matrices only)

* Like functions, sequences can be evaluated from outside the respective graphing (Sequence) mode.

Functions Mode:

* The graph can be auto-scaled.

Other:

* The gcd and lcm commands can accept more than two arguments.

* Even though they can't be used in algebraic expressions, the °C and °F units are added to the units menu.

* Many imperial (United States) units are added such as ft, acre, lb, and gal.

You can find all the details here:

https://workshop.numworks.com/firmwares

*I have to remember than Numworks does a lot more than Python. *

**How to Upgrade Your Numworks Calculator**

1. Go to the Numworks website. It is recommended that you use Google Chrome.

2. Plug in your calculator by USB port. The website should detect your calculator automatically.

3. Under your name, click on My Devices and click on the (Update my device) button. The update process takes approximately less than one minute.

4. Once the update is done, you can unplug your calculator.

Version 15.5.0 (3e071a5)

**How to Check Your Numwork's Software Version**

There are two ways that I know of:

1. Plug your calculator by USB and go to the Numworks website. Under your name, select My Devices.

- or -

2. On the calculator, press the Home key, scroll down to Settings. Press [ EXE ]. Scroll down and select About.

That's it! Enjoy,

Eddie

** Sharp EL-5100 Programs**

We can use the formula programming engine of the classic Sharp EL-5100 (1979) to store multiple formulas and invoke some simple programs.

ax^2 + bx + c = 0

x = (-b ± √(b^2 - 4ac)) / (2a)

Formulas (AER Mode):

1; f(A,B,C)=(B²-4AC) STO D ◣

2; (-B+√D)÷(2A STO E, (-B-√D)÷(2A STO F

Instructions (COMP Mode):

1. Press [ 1; ], enter A, B, and C. D is shown as ANS 1. If D ≥ 0, then the polynomial have real roots. Continue to the next step. If D < 0, then the polynomial has complex roots, stop.

2. Press [ 2; ], the two roots are displayed.

Examples:

Example 1: A = 1, B = -1, C = -3.75; Results: 2.5, -1.5

Example 2: A = 2, B = 26, C = 84; Results: -6, -7

(a + bi)^c = d + ei

The →POL stores Î¸ in I and displays r, which r is not automatically stored.

Formulas (AER Mode):

1; f(A,B,C)=A →POL B STO I, I^C×COS(JC) STO D, I^C×SIN(JC) STO E

^ represents Y^X.

Instructions (COMP Mode):

1. Set the calculator to Radians mode. Press [ 1; ].

2. You get three results: I (r), real part, imaginary part. Press [ COMP ] to see each result (ignore the first result)

Examples:

Example 1: (4 + 4i)^3 = -128 + 128i; r = 5.56854249

Example 2: (5 - 6i)^0.5 = 2.5308348108 - 1.18537961766i; r = 7.810249676

Here, we can use one formula to store values for use in the next formula.

confidence interval = A ± J * B / √C

where:

A = mean

B = variance

C = n

J = z* (see table below)

z* values:

F: 99% confidence level, value = 2.576

G: 98% confidence level, value = 2.326

H: 95% confidence level, value = 1.96

I: 90% confidence level, value = 1.645

Formulas (AER Mode):

1; 2.576 STO F 2.326 STO G 1.96 STO H 1.645 STO I ◣

2; f(A,B,C,J)=A-JB÷√C STO D, A+JB÷√C STO E

Instructions (COMP Mode):

1. Initialize by pressing [ 1; ]. When the display says ANS1 = 0, the initialization is complete.

2. Press [ 2; ], enter mean for A, press [ COMP ], enter variance for B, press [ COMP ], enter n for C, press [ COMP ], choose F, G, H, or I for J (confidence level), press [ COMP ].

Examples:

Example 1:

99% level with mean = 34.56, variance = 19.79, n = 53. For 99%, enter F for J.

Result: 22.557490316, 41.562509684

Example 2:

90% level with mean = 100, variance = 12, n = 42. For 90%, enter I for J.

Result: 96.9540518717, 103.045948128

On the EL-5100, we will have to manually keep track of the loop.

∑ f(I) from I=A to B (increment 1), result is stored in M.

Formula Template (AER Mode):

1; f(I)= STO I, 0 →M ◣

2; [enter function here] M+, 1+I STO I

Instructions (COMP Mode):

1. Press [ 1; ]. At the f(I)= prompt, store the lower limit. Press [ COMP ] **twice **to complete the initialization.

2. Press [ 2; ]. The first result is f(I). Press [ COMP ] to increase I by 1. Repeat the pattern by pressing [ COMP ]. Do this until ANS2 > B (you need to keep track manually)

3. Press [ RM ] to get the final result.

Example:

∑( (I-2)×(I+6) ) for I=1 to 5

Setup (AER Mode):

1; f(I)= STO I, 0 →M ◣

2; (I-2)×(I+6) M+, 1+I STO I

[1; ] [COMP] [COMP]

[2; ] [COMP] [COMP] ANS2 = 2

[2; ] [COMP] [COMP] ANS2 = 3

[2; ] [COMP] [COMP] ANS2 = 4

[2; ] [COMP] [COMP] ANS2 = 5

[2; ] [COMP] [COMP] ANS2 = 6

[ RM ]

Result: 55

Fun to explore different ways to solve problems, and play with retro calculators.

Eddie

**Retro Review: Sharp EL-5100**

Company: Sharp

Year Introduced: 1979

Type: Scientific, Formula Programming

Memory: 80

Operating System: Algebraic

Memory Registers: 11, A through J, M

Background

I have to give a shout out to the Pasadena Antique Mall in Pasadena, California. The EL-5100 was a lucky find for me, and the ladies at the counter were kind enough to let me walk quickly to nearby Target to get batteries so the EL-5100 can be tested. The calculator tested perfectly! If you are in the greater Los Angeles area, the Pasadena Antique Mall is great place to visit for all things retro.

The EL-5100 is a light weight calculator in a silver, thin design. The calculator is well built and the keys are solid. The keys are arranged in three sections, from left to right:

* Scientific functions

* Number keypad and arithmetic functions

* Storage and alpha keys: A-J, M

A staple of calculators from the 1970s is the physical mode switch. The EL-5100 has one mode switch:

* AER: Program and store formulas

* COMP: Computational mode

* STAT: Statistics mode, including linear regression (y = a + bx)

The EL-5100 can store up to five formula areas, with 80 steps allocated between them. The formulas can be separate or stored as a chain of formulas. An example of the chain formula:

c = √(a^2 + b^2)

d = c / (b + c)

would be stored as:

(switch to AER mode, CA)

1; f(A,B)=√(A^2+B^2) STO C ◣

2; C ÷ (B + C) STO D

(switch back to COMP)

Press [ COMP ]

(an example)

A =? (pressing COMP again takes the last value of A)

Example: Let A = 19, B = 79

[COMP]

A = ? 19 [COMP]

B = ? 79 [COMP]

1; ANS 1 = 81.25269226 (C)

[2nd F] 2;

2; ANS 1 = 0.507028563 (D)

An alternative way to chain formulas (multistep):

1; f(A,B)=√(A^2+B^2) STO C, C ÷ (B + C) STO D

Example: Let A = 19, B = 79

[COMP]

A = ? 19 [COMP]

B = ? 79 [COMP]

1; ANS 1 = 81.25269226 (C) [COMP]

2; ANS 2 = 0.507028563 (D)

You can store immediate results, however, they will end the execution. However, this is still handy when you are using the M register and the M+ feature.

* Note: In AER mode, the [ COMP ] key is the comma.

In STAT mode, it was common for Sharp calculators to assign data entry keys to the M register keys.

[ RM ] becomes CD (clear data)

[ →M ] becomes the comma for bivariate data (x,y)

[ M+ ] becomes DATA for storing data

The multiplication key can be used to store data with frequency greater than. However, you can do mathematical operations as long as they are enclosed in parenthesis.

Even though the variable keys A-J are not available during STAT mode, the stat values are stored in the following variables and can be used later in COMP mode.

E = n

F = ∑x

G = ∑x^2

H = ∑xy

I = ∑y

J = ∑y^2

The EL-5100 ushered in a category of formula storage calculators. Here is a comparison table between 1979's EL-5100 and 1989's TI-68.

EL-5100 | TI-68 | |
---|---|---|

1979 | Year of Introduction | 1989 |

3 x SR44/LR44/357 | Batteries | 1 x CR2032 |

landscape | Form | portrait |

5, sequential | Number of Storage Areas | 1 at a time, as memory allows |

80 | Number of Steps | 440 (55 registers) |

y = a + bx, r | Linear Regression | y = SLP x + ITC, COR |

A through J, M | Variable Names | variable names up to 3 characters |

chain formulas, physical mode switch | Unique Features | complex numbers, base conversions, integrals, solver, conversions |

The EL-5100 is a simple calculator which is a joy to use.

Eddie

**TI-NSpire CX II and TI-84 Plus CE: Enhanced Graphing Table**

**Introduction**

The program TABLEYX allows the user to enter a function, not only store it for graphing, but also display an analytic table. Results are stored in lists so they can be used for further analysis.

Both the TI-NSpire CX II (.tns) and TI-84 Plus CE (.8xp) version can be downloaded here.

**TI-NSpire CX Version**

Table of contents:

1.1 The Notes Page

1.2 Calc Page: run tableyx() here

1.3 Graph Page: it should update automatically each time tableyx() is run

14. Table Page: updates when tableyx() is executed

1.5 Program Listing

Lists:

xlist: x coordinates

ylist: y(x)

dislist: Euclidean distance from (0,0) to (x,y)

arclist: Arclength of y(x) from 0 to x

derlist: Derivative at (x,y)

intlist: Integral of y(x) from 0 to x

Program:

Define tableyx()=

Prgm

:© set approximate mode

:setMode(5,2)

:© main program

:Request "y(x)? ",y(x)

:Request "Î”x? ",dx

:Request "Number of steps? ",n

:seq(i,i,0,dx*n,dx)→xlist

:seq(y(i),i,0,dx*n,dx)→ylist

:seq(∫(y(x),x,0,i),i,0,dx*n,dx)→intlist

:seq(nDerivative(y(x),x=i),i,0,dx*n,dx)→derlist

:seq(approx(arcLen(y(x),x,0,i)),i,0,dx*n,dx)→arclist

:√(xlist^(2)+ylist^(2))→dislist

:Disp "Done. See the next page for results."

:EndPrgm

**TI-84 Plus CE Version**

When the program ends:

Press [ graph ] to see the graph.

Press [ stats ], select Edit... to see the lists in a list editing format.

Lists:

L1: x coordinates

L2: y(x)

L3: Euclidean distance from (0,0) to (x,y)

L4: Derivative at (x,y)

L5: Integral of y(x) from 0 to x

Program:

Float

Radian

Input "Y(X)=",Str1

String>Equ(Str1,Y₁)

Input "CHG X? ",D

Input "NO OF STEPS? ",N

seq(I,I,0,D*N,D)→L₁

seq(Y₁(I),I,0,D*N,D)→L₂

√(L₁²+L₂²)→L₃

seq(nDeriv(Y₁(X),X,I),I,0,D*N,D)→L₄

seq(fnInt(Y₁(X),X,0,I),I,0,D*N,D)→L₅

ClrHome

Disp "RESULTS","L₁: X","L₂: Y","L₃: DIST FROM (0,0)","L₄: D/DX Y(X)","L₅: INTEGRAL FROM X=0","PRESS STAT, EDIT"

Pause

SetUpEditor L₁,L₂,L₃,L₄,L₅

Eddie

** Retro Review and Comparison: TI-82 Advanced**

I can officially say that I have a French calculator.

Quick Facts:

Models: TI-82 Advanced

Company: Texas Instruments

Manufactured: 2015-2021

Type: Graphing

Battery: 4 AAA

Country: France

Keyboard

All the TI-82 Advanced is a French calculator, where the keys and functions are in French. Examples include:

French: suppr, English: delete

French: dessin, English: draw

French: annul, English: clear

French: rappel, English: recall

I like the how the keys respond and how comfortable the keys feel. The screen is a monochrome screen but the contrast between the screen and its text.

**More Like the TI-84 Plus**

The TI-82 Advanced is pretty much the equivalent of the TI-84 Plus. I put together a comparison table between three calculators:

* The basic TI-82 (United States)

* TI-82 Advanced

* TI-84 Plus (monochrome screen)

The table lists the commands available in several menus including Lists, Distributions, Program Editing, and Variables. You can download the comparison here.

**Python to Come**

In the Fall of 2021, Texas Instruments will release the next version of the TI-82 Advanced: the TI-82 Advanced Edition Python. The new TI-82 Advanced will retain the classic TI-82 casing, including being powered by AAA batteries, but will have a color screen and have a Python programming mode.

You can read the about the TI-82 Advanced Edition Python here:

https://education.ti.com/fr/produits/calculatrices/graphiques/ti-82-advanced-edition-python (French)

https://tiplanet.org/forum/viewtopic.php?p=259509#p259509 (French)

Eddie

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