## Monday, November 7, 2022

### Retro Review: Texas Instruments TI SR-51-II

Retro Review:   Texas Instruments TI SR-51-II

Quick Facts

Model:  SR-51-II

Company:  Texas Instruments

Years:  1976

Type:  Scientific

Batteries: 1 × BP6, with AC-Adapter**

Operating Modes:  AOS

Number of Registers: 3

Display:  10 digit - red seven segment digits

Leather Case

** I purchased the calculator on eBay not to long ago from night_owl_items, who made it so the SR-51 II can run on two AA batteries, making it one of the kind and extend it's life.

Features

*  Trigonometric functions and inverses

*  Hyperbolic functions and inverses

*  Logarithms and exponentials

*  Factorials of positive integers

*  Percent and percent change

*  Arithmetic, powers, and roots

Conversions

There are eight conversions:

* in · mm

* gal · l

* lb · kg

* °F · °C

* D · R  (degrees - radians)

* DMS · DD (degrees-minutes-seconds - decimal degrees)

* P → R (polar - rectangular conversions)

The [ 2nd ] key sequence converts left to right

The [ 2nd ] [ INV ] key sequence converts right to left

Angle Modes

The SR-51-II has the three customary angle modes:  degrees, radians, and grads.  Unfortunately there is no angle mode indicator.   The way to:

Degrees Mode:  0.5 sin^-1 returns 30

Radians Mode:  0.5 sin^-1 returns .5235987756

Grads Mode:  0.5 sin^-1 returns 33.33333333

Storage and Storage Registers

The SR-51-II has three memory registers.   The calculator also has storage arithmetic:

SUM:  STO+

INV SUM:  STO-

PROD:  STO×

INV PROD:  STO÷

The CONST Function

The CONST is an access to common scientific functions, but allows the user to do a short arithmetic calculation, includes roots, powers, and percent change.

Example:  Subtract 100 from 290, 370, and 480 respectively.

100 [ - ] [ 2nd ] (CONST)

290 [ = ] returns 190

370 [ = ] returns 270

480 [ = ] returns 380

Example 2: Multiply 172, 288, and 382 by 6 respectively.

6 [ × ] [ 2nd ] (CONST)

172 [ = ] returns 1032

288 [ = ] returns 1728

382 [ = ] returns 2292

Statistics

The statistics modes have one and two variable statistics.  What is unique of the SR-51-II is that the y-variable is primary. However, entering two variable statistics remain the usual:  x [ x<>y ] y [ Σ+ ].

[ 2nd ] (MEAN):  mean of y data;  [ INV ] [ 2nd ] (MEAN):  mean of x data

[ 2nd ] (S.DEV):  standard deviation of y data;

[ INV ] [ 2nd ] (S.DEV):  standard deviation of x data

[ 2nd ] (VAR):  population variance of y data;

[ INV ] [ 2nd ] (VAR):  population variance of x data

Solid calculator.  I wish the SR-51-II had a random number function and angle mode indicator.

Source:

Woerner, Joerg.  "Texas Instruments SR-51-II" Datamath.  December 5, 2001.   Last Retrieved November 1, 2022.  http://www.datamath.org/Sci/MAJESTIC/sr-51-II.htm

Eddie

All original content copyright, © 2011-2022.  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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