## Thursday, July 31, 2014

### Sharp EL-501X (today) vs TI-35 Plus (1989)

TI-35 Plus Notes vs Sharp EL-501X (and almost all of its clones)

Ever wanted a TI-35 Plus? First you could go to eBay or other online stores and try to hunt one down or invest up to \$10 for one of the many close-version that are still manufactured and sold today. There is even a version sold at the Dollar Store! (The keyboard of that \$1 Store I bought is crappy.) Today I will be comparing the Sharp EL-501X against the 1989 TI-35 Plus (and its solar sister, TI-36 Solar (no X)).

Since I never actually owned a TI-35 Plus, all the information will be from its manual. I did buy a TI-36 Solar guidebook, 20 years ago or so, from a clearance bin at Toys R Us of all places. The Sharp EL-501X I bought this week primarily for this blog entry, and to replace a blue cased EL-501X I gave to my cousin's daughter.

Source of the TI-35 Plus information: www.datamath.org

TI-35 Plus Page: http://www.datamath.org/Sci/Modern/TI-35-PLUS.htm

Side plug: Datamath is an excellent web page for all things Texas Instruments calculators, past and preset.

Commonalities

Internal Digits: 12

Modes:
Computational
Complex Mode
Base Display Modes: Binary, Decimal, Octal, Hexadecimal
One Variable Statistics

Complex Mode is limited to arithmetic. The real part is stored and recalled using the [ a ] key and the [ b ] key is for the imaginary part. ( a + bi )

Base Display Modes (except for Decimal) is limited to arithmetic. To convert numbers, just call their respective mode.

Number of memory registers: 1

Factorial Function: n!. Only takes positive integers or zero unless an error occurs.

Polar/Rectangular Conversions:
[ a ] is used for x and r
[ b ] is used for y and θ

Basic Scientific Function set: hyperbolic functions, trigonometric functions and inverses, exponential functions and inverses, reciprocal, square root, cube root, power, arithmetic, π, 3-decimal random number (usually labeled RND)

Differences

Display:
TI-35 Plus: 10 digits plus 2 digit exponent
EL-501X:10 digits or 8 digit plus 2 digit exponent

Exchange Key:
TI-35 Plus has two: EXC to change the number in the display with the number in the memory register. x<>y exchanges operands in power, root, division, and subtraction calculations.
EL-501X: Only the latter is present, often symbolized by a vertical line with up and down arrows. ( [2ndF] [ ( ] )

Decimal Display Settings:
TI-35 Plus: Four permanent modes: floating, fixed, scientific, engineering
EL-501X: Two permanent modes: floating and fixed. Numbers can be toggled between floating/fixed and scientific notation by pressing [ F ←→ E ]

Things the TI-35 Plus had that the EL-501X and most of the clones do not:

Permutations and Combinations. The TI-35 Plus facilitated the use of the [ a ] and [ b ] keys.

Normal Cumulative Distribution Functions (mean = 0, variance = 1, given z):
R(z): area between 0 and z
Q(z): area from z to positive infinity (upper tail)
P(z): area from negative infinity to z (lower tail)

In more advanced calculators and mathematical software, the normalcdf function calculates P(z) (lower tail).

One variate of the EL-501X, the Canon F-604 has permutations, combinations, memory exchange, and fractions. Unfortunately the one I bought not to long ago, the zero key reseted the calculator, so I had to return it. Hopefully it is not the case with all F-604s.

Yes - entry level scientific calculators still exist in the market.

Take care everyone, thanks for comments and questions. Much appreciated. Eddie

This blog is property of Edward Shore. 2014