## Thursday, January 19, 2017

### Retro Review: TI-60X

Retro Review: TI-60X TI-60X.  Yes I forgot the multiplication sign here.

Company:  Texas Instruments
Years:  1991 – 1995? 2000?
Year of my TI-60X:  1991 (specifically week 46, November 1991)
Type:  Scientific, Formula Storage
Number of Steps: 96, shown in units of registers (12 registers of 8 steps each)
Operating System: Algebraic
Memory Registers: 12 (A through I, X, Y, Z)
Regressions Available:  Linear

Chipset:  Toshiba T9838
Battery: 1 CR2032

My late Uncle Ralph bought a TI-60X for me in 1992 (I think it was in ’92).  It was my first year of high school.  Uncle Ralph encouraged my love for calculators. (Thanks for all you did for me Uncle)

A Rich Feature Set

The TI-60X operates in Algebraic mode.  Simply, type in the expression as its written, and press [ =/ENTER ].

The TI-60X isn’t programmable in the traditional sense (keystroke or BASIC) but rather you can store formulas (A = π * B^2, for example) for later use.  I think the TI-60X is the first of its kind to store formulas.  Today, formula storage is a feature of the Sharp EL-520W.  More on this later.

You have your standard linear regression capabilities.  However, instead of the usual labels a, b, and r, you have ITC (intercept), SLP (slope), and COR (correlation) respectively.  If find these labels much helpful since calculators sometimes tend to switch the roles of a and b in linear regression mode.  Entry is rather easy, just enter the data point and press [ Σ+ ] and you are good to go.  No separate declaration of stats mode needed.

Equation:  y = INT + SLP * x

The Base conversions are on the TI-60X as well.  We also get the logical functions AND, OR, XOR, XNOR, NOT, and 2’s (compliment).  The TI-60X distinguishes the variables A-F from the hexadecimal A-F by assigning the latter set to the 3rd functions of the reciprocal, square, square root, and the trigonometric keys.  On the screen, hexadecimal letters are in bold while storage registers are not.

Fractions are included, as well as the decimal to/from fraction conversion.  The TI-60X has the following additional conversions:

* degrees, decimal-minute-seconds
* polar, rectangular coordinates
* inches, centimeters
* gallons, liters (litres)
* pounds, kilograms
* degrees Fahrenheit (°F), degrees Celsius (°C)

The Blocky Display

Can we talk about the display for a moment?  The text on the TI-60X’s screen is blocky.  According to the Datamath Calculator Museum, the character layout is 5 x 4 dots instead of the usual 7 x 5.  This display could be a throwback to the calculator display of the 1970s and 1980s where the numbers were made of linear segments.

The article from Datamath on the TI-60X:  http://www.datamath.org/Sci/Modern/TI-60x.htm

Formula Programming, Simultaneous Equations, and Integration

Up to 12 formulas can be stored, and they can have the labels A, B, C, D, E, F, G, H, I, X, Y, and Z.  The formulas can have more than one variable. Pressing [SOLVE] allow the user to calculate the formula, with each independent variable being prompted.  If there is a numerical value in the independent variable, the TI-60X will display it as a default choice.

When the “SOLVE YN?” and “REVIEW YN?” prompts appear, the plus key acts as NO and the equals keys acts as YES.

Integration is pretty easy.  At the appropriate prompted variable, press [2nd] [ , ] (dx) to insert the dx indicator.  You will be asked for a lower limit, upper limit, and the number of intervals.  I am assuming Simpson’s method but I’m not 100% sure.

Simultaneous equations of 2 x 2 and 3 x 3 linear systems are offered.  Execution takes up 2 or 3 registers respectively.   Solutions are stored in X, Y, and for 3 x 3 systems, Z.

Example: y = 2 * x * sin x

Enter the formula:
Change to Radians mode by pressing [3rd] [LOG] (DR>) until the R indicator is displayed.

Press [2nd] [ EE ] (FMLA).  At the “NAME?” prompt, press [ ( ] for Y (ALPHA is automatically turned on at this point) and enter the equation.

Calculate y(π/3).  Press [SOLVE].  At X, enter π/3.  Result:  Y = 1.813799364.

Integrate y(x) from 0.5 to 1, use 20 intervals.  Call up the Y= formula again, press [SOLVE].  At the X= prompt, clear the number and enter dx.  Enter the required parameters.  After calculation, the TI-60X displays Y = 0.521068842.  The integral is now stored in Y.

Final Verdict

For what it’s set out to do, the TI-60X accomplishes it rather well.  The calculator is rich with features and there is some storage for some formulas.  I also like the bolder blocky numbers in the display, they are easier to read.  I think the TI-60X launched the advanced scientific calculator genre which is now common place.

Yes, this calculator is worth collecting.  I’m not sure what the prices are to purchase a used on from eBay, Amazon, or other shopping website, but I imagine it’s not expensive.  (I think the 60X was about \$30-\$40 when it was sold new back in the 1990s).

Thank you for comments and support.  Until next time,

Eddie

This blog is property of Edward Shore, 2017.

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