SR-50

SR-50 (1974)

Successor SR-50A (1975)

The SR-50 from Texas Instruments (TI) is a technical and scientific calculators . It was the first TI model with trigonometric and logarithmic functions. The abbreviation SR means slide rule , English. for slide rule .

Chronological order

On January 15, 1974, Texas Instruments introduced the SR-50 to the US market about two years after the presentation of the HP-35 from Hewlett-Packard . He initially cost around 170 dollars ; in Germany it was offered for 520 DM, which today corresponds to a sum of 879 $ or 738 EUR after adjusting for purchasing power. An HP-35 was more than double that price at $ 395 in 1972 ($ 2,409 today).

In March 1975, the successor SR-50A came out with the same range of functions and key arrangement. The model, in the design of the SR-52 presented six months later , was cheaper to manufacture and only cost around $ 110 ($ 521 today).

properties

Like all its successors, the SR-50 uses the algebraic hierarchy to a limited extent , i.e. the input of every mathematical expression from left to right (but function calls according to the parameters!). The TI-own Algebraic operation system (AOS) provides with three internal registers X, Y, Z, the operator precedence in the mathematical notation .

In contrast, the HP-35 uses Reverse Polish Notation (UPN) for input . This requires fewer keystrokes, but must first be learned by the user. Their advantages only come into play with more intensive use and when working with complicated formulas.

Compared to the more expensive HP-35 / HP-45, which did not offer this option, the SR-50 had keys for direct calculation of the faculty ( ) and hyperbolic functions . Many newer TI computers, such as the programmable models SR-56 / TI-57 , again dispensed with these function keys. ${\ displaystyle x!}$

The SR-50 has a membrane keyboard with 40 keys as well as a 14-digit LED - seven-segment display . A charger for the NiCd battery pack was included in the scope of delivery .

Functions

Open device. The date code 035 in the battery compartment corresponds to 3rd week 1975

Display in scientific notation : 10-digit mantissa with 2-digit exponent (to base 10 ), plus two minus signs if necessary

Algebraic input (AOS - Texas Instruments Algebraic Operation System ) with consideration of the operator precedence for max. 3 open operations

Two slide switches: Selection of arc ( R AD) or degree ( D EG) for the trigonometric functions as well as on / off switch

D / R key to convert degrees to radians (or vice versa - depending on the position of the R / D slide switch)

sin, cos , tan with inverse functions ( arc functions : arcsin, arccos , arctan ) and the hyperbolic functions sinh, cosh , tanh with their inverse functions (area functions : arsinh, arcosh , artanh )

Circle number key ( )

{\ displaystyle \ pi \ approx 3 {,} 141592 \ ldots \}

Square number ( ), and - root ( or ), the reciprocal (1 / x), ${\ displaystyle x ^ {2}}$ ${\ displaystyle {\ sqrt {x}}}$ ${\ displaystyle {\ sqrt [{2 \,}] {x}}}$

General Power - ( ) and root function ( ). Additional key to swap x and y or when dividing dividend and divisor. ${\ displaystyle y ^ {x}}$ ${\ displaystyle {\ sqrt [{x \,}] {y}}}$

Tens - ( ) and natural ( ) logarithm ${\ displaystyle \ log}$ ${\ displaystyle \ ln}$
Exponential function ( ) ${\ displaystyle e ^ {x}}$
Faculty ( ) ${\ displaystyle x!}$
Accumulation key (Σ) for totalizing in the memory

Number format and calculation accuracy

The device calculates internally using 13 digits. Rounded to 10 places, the result is shown in the display with a 10-digit mantissa and 2-digit exponent plus any negative sign .

Technical specifications

ALU (Arithmetic and Logic Unit): TMC0501
SCOM (Scanning Read Only Memory): TMC0521
Display driver: 2 × 27882
Power supply: NiCd battery pack BP1 (3.6 V) and charger AC9200 or AC9900

Web links

Commons : Texas Instruments Calculator - Collection of Images

Texas Instruments SR-50 in the Datamath Calculator Museum ( datamath.org )
The SR-50 super calculator from Texas Instruments advertising flyer (PDF; 1.8 MB, 3 pages)
Maintenance Manual Service instructions from Texas Instruments with circuit diagrams etc. at rskey.org, accessed on April 29, 2018 (English PDF; 1.7 MB, 28 pages)

Individual evidence

↑ The SR-50 on datamath.org (Eng.)
↑ ^a ^b ^c The amounts were determined with the template: Inflation and refer to the previous January.
↑ The SR-50A on datamath.org (Eng.)
↑ The SR-52 on datamath.org (Eng.)

[datamath_SR-50-1] The SR-50 on datamath.org (Eng.)

[Vorlage-Inflation-2] The amounts were determined with the template: Inflation and refer to the previous January.

[3] The SR-50A on datamath.org (Eng.)

[4] The SR-52 on datamath.org (Eng.)