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)

* G · R  (grads - 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


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