Keystroke programming...
8 addressable memory registers...
The mostused Advanced scientific, engineering and mathematics functions...
in a new 6 ounce calculator...
Now you can solve repetitive or iterative problems quickly by creating the exact programs you needright on the spot. Key in a problemsolving sequence of keystrokes (a program) just once. Then run your program as often as you wish ... simply by pressing a key.
Advanced scientific, engineering and mathematical functions are conveniently preprogrammed in the calculator for use in your keyboard problem solving, or as a part of your programs. As a result, you'll do your problem solving in much less time and with greater accuracy.
You can store and retrieve numbers as constants or for use in later calculations directly from the keyboard, or automatically as part of your program. And, you can do register arithmeticdirectly add to, subtract from, divide into, or multiply the contents within each register. This makes data manipulation easy.
The HP25 has all of these features ... in addition to HP's advanced design, fourregister stack, RPN logic, and quality engineering ... at $195.00.
With the introduction of the HP25the lowestpriced HewlettPackard programmable pocket calculatorthe speed and convenience of programming is now available to just about everyone who needs it. And if you deal with repetitive problems, you need it.
A program, in this case, is a sequence of keystrokes used to solve a problem. The HP25 can retain and repeat a program up to 49 steps in length. So you don't have to press the same keys again and again when the same problem is worked with different data.
Simply set the HP25 to PROGRAM mode by flipping a switch. Then press the keys you'd normally press to solve the problem. (But don't enter the data.) Your program is retained in the HP25's program memory.
To solve the problem, switch to RUN mode and enter the data. Then press the "Run/Stop" key to run your program. Seconds later, your answer appears on the HP25 display. To solve other problems using the same program, just enter the new data and press the "Run/Stop" key again.
Because your program does the calculation automaticallyjust sit back and watch itthere's less chance for error than if you had to repeat the keystroke sequence yourself step by step. Also, it takes but a fraction of the time.
Programming is easy with the HP25. You don't have to learn computer language." The keyboard controls are in plain English (abbreviations). Every step and function is clearly explainedwith illustrated, stepbystep directionsin the HP25 Owner's Handbook. To see just how easy it is to program the HP25, review the example of a typical problem from the HP25 Applications Programs Book in the box at right.
The HP25's program memory consists of 49 steps, numbered 01 through 49. Your program remains stored for as long as you leave the HP25 turned on, or until you erase or change your program.
The program memory uses a simple numeric code, based on the position of each key on the keyboard. For example, "31" means "3 rows down, 1st key"the "ENTER" key. Some key codes will appear as two or three pairs of numbers. To conserve steps, each prefixed function (e.g., f, mean) takes only one program memory step. When you singlestep through a program, the code numbers are visible on the HP25 display. This system lets you know where you are in the program memory and what your program looks like stepbystep. Testing and editing your programsto make sure complex solutions are correctis thus greatly simplified.
The "Back STep" and Single STep" keys let you review the entire memory one step at a time in either direction. Or you can press the "Go TO" key, along with the number of the step you want.
If you want to change your program, simply stop it at the appropriate step and key in a new entry, which will overwrite the previous one. To test your program a step at a time, switch to RUN and press "SST" repeatedly. You will see the numeric code when you press the key and the intermediate solution when you release the key.
Like a computer, the HP25 can be programmed to make decisions, because it can do conditional branching.
You can program it to test the relationship between two values, by means of these tests:
Depending on the outcome of the tests, the HP25 will automatically skip a step of the program ... or it will continue through the program in sequence.
Or, by means of the "Go TO" key, you can program the HP25 to branch directly to a specified step, and then continue executing the program.
Both types of branchingconditional and directare useful in solving a variety of programming problems ... and make your work easier.
Another new feature on the HP25 is the ''PAUSE" key. You can use it to momentarily interrupt (about one second per Pause command) the program execution and display the contents of the X register. This gives you the opportunity to review or write down intermediate results, data, the value of a counter or other output. The example below shows one use.
The ABSolute value function allows you to get the absolute value and magnitude of a number within a programmed calculation.
The INTeger/FRACtion truncation function allows you to keep only the integer or fractional portion of a number. This is especially useful in base conversion, random number generator and other specialized routines. In addition, you can integerfractionalize your data and double the number of data points you can save in the registers.
Suppose you were asked to plot the trajectory of a stone which is hurled into the air with an initial velocity V at an angle to the horizontal of 0.
Neglecting drag due to friction with the atmosphere, the following equations describe the stone's x and y coordinates as functions of the time t;
x=vt Cos theta  y=vt sin theta1/2 gt^{2} 
Where:  x=the horizontal distance the stone has traveled 
y=height of the stone  
g=acceleration due to gravity (9.8 m/s^{2} or 32 ft/s^{2}) 
Using a page from the HP25 Applications Programs Book as a guide, here's how you would program the solution on the HP25:
Key Entry 
Display  Comments  

Line  Code  
00  
f→R  01  14 09  Use polartorectangular for 
STO 2  02  23 02  v_{x} = v cos theta = horiz. vel. 
x⇔y  03  21  
STO 3  04  23 03  v_{y} = v sin theta = vert. vel. 
0  05  00  
STO 4  06  23 04  Initialize: t = 0 
RCL 0  07  24 00  Start f loop 
STO + 4  08  23 51 04  Next time interval: 
RCL 4  09  24 04  t = t + delta t 
g x^{2}  10  15 02  
RCL 1  11  24 01  
×  12  61  
2  13  02  
÷  14  71  
CHS  15  32  
RCL 4  16  24 04  
RCL 3  17  24 03  
×  18  61  
+  19  51  y = v_{y}t  1/2 gt^{2} 
RCL 4  20  24 04  
RCL 2  21  24 02  
×  22  61  x = v_{x}t 
RCL 4  23  24 04  
f PAUSE  24  14 74  Pause to display t 
R down  25  72  
R/S  26  74  Halt to display x 
x⇔y  27  21  
R/S  28  74  Halt to display y 
GTO 07  29  13 07  Branch back for next t 
30 
Step  Instructions  Input Data / Units  Keys  Output Data / Units 
1  Key in program  
2  Store time interval  delta t  STO 0  
3  Store gravitational constant  g  STO 1  
4  Input angle and initial speed  theta  ENTER  
v  f PRGM  i  
5  Perform step 5 and 6 any number of times: Display horizontal distance.  R/S  t(x)  
x  
6  Display height  R/S  y  
7  To change theta or v, go to step 4.  
To change delta t or g, go to appropriate step, store new value, then go to step 4. 
Plot the trajectory of a stone cast upwards with a velocity of 20 m/s at an angle of 30° to the horizontal. Use intervals of 1/4 second between the points plotted. Let g=9.8 m/s^{2}.
0.25 STO 0 9.8 STO 1 30 ENTER 20 f PRGM R/S 0.25 (t_{1}) 4.33 (x_{1}) R/S 2.19 (y_{1}) R/S 0.50 (t_{2}) 8.66 (x_{2}) R/S 3.78 (y_{2}) R/S 0.75 (t_{3}) 12.99 (x_{3}) R/S 4.74 (y_{3})
Continue until y becomes negative.
A table of these results is shown below:
t  0.25  0.50  0.75  1.00  1.25  1.50  1.75  2.00  2.25 
x  4.33  8.66  12.99  17.32  21.65  25.98  30.31  34.64  38.97 
y  2.19  3.78  4.74  5.10  4.84  3.98  2.49  0.40  2.31 
The HP25 is an advanced scientific pocket calculator with dozens of keyboard commandsincluding the functions most used by scientists and engineers.
To make the HP25 smaller, one row of keys was eliminated. But, to keep the advanced capability, most keys now perform three commands. Some commands are labeled in gold above a key, or labeled in blue on the underside of a key, and activated by first pressing the appropriate gold or blue prefix key(s). (All functions may be incorporated into a program for automatic operation.)
You can convert rectangular coordinates to polar coordinates or vice versa, enabling you to do vector arithmetic quickly, easily and accurately.
You can convert angles (times) in decimal degrees (hours) to angles (times) in degrees (hours)/minutes/seconds ... or vice versa.
Of course the HP25 is also preprogrammed with the six basic trig functionssin x, arc sin x, cos x, arc cos x, tan x, arc tan x.
The HP25 computes both natural and common logarithms as well as their inverse functions (antilogarithms).
The Σ+ key automatically calculates n, Σx, Σx^{2}, Σy, Σy^{2}, Σxy for statistical and vector calculations. Data may be deleted via the "SUM" key.
The HP25 calculates the mean and standard deviation.
When you first turn on the HP25, the display "wakes up" in fixed point notation, with the display rounded to two decimal places. By pressing "f", "FIX" and a number key (0 to 9), you can specify the number of decimal places. Or you can select scientific notation, by pressing "f", "SCI'' and a number key to specify the number of decimal places (up to seven digits after the decimal point).
New to HP pocket calculators is engineering notation, which allows all numbers to be shown in a modified scientific notation with exponents of 10 that are multiples of three (e.g., 10^{3}, 10^{6}, 10^{12}). This is particularly useful in scientific and engineering calculations, where units of measure are often specified in multiples of 10^{3}. When the HP25 is in engineering notation, the first three digits are always present but you can display up to 8 total.
Whichever notation is selected, the HP25 always maintains the complete 10digit number internally. Also, the HP25 switches the display automatically from fixed point notation to full scientific notation whenever a number is too large or too small to be seen in fixed point notation.
Instead of writing down and reentering numbers manually, you can simply store them in any or all of the eight addressable memory registers, and recall them when needed. The registers may also be used for register arithmeticdirectly adding to, subtracting from, dividing into or multiplying the register contents. Eight addressable registers and register arithmetic make data manipulation easy, especially with programmed problemsolving.
Like all other HP pocket calculators, the HP25 uses HP's famous "RPN logic" system and a fourregister stack. Intermediate answers are automatically stored, then automatically reentered into the calculation. The "Last x" register stores the last input for instant recall, to correct a keystroke error or for use in another calculation.
Optional accessories available: reserve power pack; security cradle; pads of programming worksheets. (Details included with the HP25.)
These HP25 Applications Programs54 in allhave been drawn from the varied areas of algebra and number theory, trigonometry and analytical geometry, numerical methods, statistics, finance, surveying, navigation, and games. Each program is furnished with a full explanation which includes a description of the problem, any pertinent equations, a list of keystrokes to be entered into program memory, a set of instructions for running the program, and an example or two, with solutions. To use these programs does not require any proficiency in programming.
The first program in each chapter contains, in addition to the usual explanations, a more detailed description of the problem, a commented list of the program keystrokes with a stepbystep tracing of the contents of the stack registers, and a list of the keystrokes required to solve the example problem. Whenever an interesting programming technique is used in one of these programs, it is described in a short section headed ''Programming Remarks."
Thus, whether your interest lies in solving a particular problem in a specific area, or in learning more about the programming power of your calculator, this book will help you get the most from your HP25.
It comes with your HP25.
The HP25 is more than advanced technology ... it's the result of dedication to uncompromising quality 

If you appreciate the precision and accuracy of fine instruments, you'll appreciate the solid design and precision construction of the HP25. Careful attention has been given to each detail, no matter how minute. Examples are the double injectionmolded keys with symbol identifications that never wear off; moisture barriers that protect against liquids; critical connections that are goldplated for maximum efficiency; contoured "humanengineering" for comfortable "fit"in your hand or pocket. Just a quick glance at the HP25 specifications tells the storyuncompromising quality is value that comes with every HewlettPackard product.  Prove to yourself how the HP25 solves your problems quickly, accurately, easily! To see and "feel" the HP25 Scientific Pocket Calculator, contact your local Hewlettpackard dealer. For the one nearest you, call Customer Service on our tollfree number: (800) 5387922, (in California, call (800) 6629862). 
Program writing capability ¶ Single step execution or inspection of a program ¶ Pause (to display intermediate result) ¶ Program editing capability ¶ 8 relational tests: x<y, x≥y, x≠y, x=y, x<0, x≥0, x≠0, x=0 ¶ Conditional branching ¶ Direct branching
Trigonometric functions: 3 angular modes (degrees, radians, grads) ¶ Sin x ¶ Arcsin x ¶ Cos x ¶ Arccos x ¶ Tan x ¶ Arc tan x ¶ Rectangular coordinates <> Polar coordinates ¶ Decimal angle (time) <> Angle in degrees (hours)/ minutes/seconds.
Logarithmic functions: Log x ¶ Ln x ¶ e^{x} ¶ 10^{x}
Statistical functions: Mean and standard deviation ¶ Positive and negative summation giving n, Σx, Σx^{2} Σy, Σxy
Other functions: Integer (gives only integer portion of number) ¶ Fraction (gives only fractional portion of number) ¶ Absolute (gives absolute value of x) ¶ y^{x} ¶ sqrt(x) ¶ 1/x ¶ π ¶ x^{2} ¶ % ¶ Register arithmetic in all 8 addressable registers ¶ Addition, subtraction, multiplication or division in serial, mixed serial, chain or mixed chain calculations
Data storage and positioning operations: Data entry ¶ R↓ (Stack roll down) ¶ x⇔y (x,y interchange) ¶ Data storage ¶ Data recall ¶ Change sign ¶ Enter exponent
4register stack ¶ "Last x" register ¶ 8 addressable registers ¶ Program memory for storage of up to 49 steps
Displays up to 10 significant digits, 8 plus twodigit exponent in scientific and engineering notation, and appropriate signs. Three selectable display modes: fixed point (with automatic overflow and underflow into scientific), engineering and scientific, with dynamic range of 10^{99} to 10^{99}. Automatic decimal point positioning. Selective roundoff; range 010 digits in fixed point; 08 digits in scientific; 08 in engineering notation. "Error" appearing in display indicates improper operation; low battery indicator.
Operates on fastcharge battery pack or AC. (Battery recharges in 617 hours.) Tactile feedback keyboard. Polyethelene liquidbarrier shield under keyboard. Compact case of highimpact plastic with recessed display. Recessed recharger/AC plug receptacle. Solid state electronics.
Power:
AC: 115 or 230 V, +/ 10%, 50 to 60 Hz, 5 watts. Battery: 500 mw derived from nickelcadmium rechargeable battery pack.
Weight:
HP25: 6 ounces (170 g) with battery pack. Recharger: 5 ounces (142 g). Shipping wt.: Approx. 1.5 lbs. (.7 kg).
Dimensions:
Length: 5.1 inches (13.0 cm). Width: 2.7 inches (6.2 cm). Height: 1.2 inches (3.0 cm).
Temperature range:
Operating: 32 degrees F to 11 3 degrees F (0 degrees C to 45 degrees C). Charging: 59 degrees to 104 degrees F (15 degrees C to 40 degrees C).
Ever since 1939, HewlettPackard has been a leading designer and manufacturer of specialpurpose electronic equipment for measurement and computation.
HewlettPackard pocket calculators have become the standard of excellence in the industry, and more than 1,000,000 are in use throughout the world.
This excellence is achieved via advanced technology ... final assembly in HP's own facilities ... and thorough testing not only for mechanical operation, but for accuracy in computation.
The HP25 is warranted against defects in materials and workmanship for one year from the date of delivery. During the warranty period, Hewlettpackard will repair, or at its option, replace at no charge components which prove to be defective, provided the calculator is returned shipping prepaid, to HewlettPackard's Customer Service facility.
This warranty does not apply if the calculator has been damaged by accident or misuse, or as a result of service or modification by other than an authorized HewlettPackard Customer Service facility. No other express warranty is given by Hewlettpackard. HEWLETTPACKARD SHALL NOT BE LIABLE FOR CONSEQUENTIAL DAMAGES.
HewlettPackard reserves the right to make changes in materials and specifications without notice.
Sales and service from 172 offices in 65 countries 19310 Pruneridge Avenue  Cupertino, Cal. 95014
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