Texas Instruments TI-80 User Manual

TI-80

GRAPHING CALCULATOR

GUIDEBOOK

TI-GRAPH LINK, Calculator-Based Laboratory, CBL, CBL 2, Calculator-Based Ranger, CBR, Constant Memory, Automatic Power Down, APD, and EOS are trademarks of Texas Instruments Incorporated.

Windows is a registered trademark of Microsoft Corporation. Macintosh is a registered trademark of Apple Computer, Inc.

Important

US FCC Information Concerning Radio Frequency Interference

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In no event shall Texas Instruments be liable to anyone for special, collateral, incidental, or consequential damages in connection with or arising out of the purchase or use of these materials, and the sole and exclusive liability of Texas Instruments, regardless of the form of action, shall not exceed the purchase price of this calculator. Moreover, Texas Instruments shall not be liable for any claim of any kind whatsoever against the use of these materials by any other party.

This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference with radio communications. However, there is no guarantee that interference will not occur in a particular installation.

If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, you can try to correct the interference by one or more of the following measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between the equipment and receiver.

• Connect the equipment into an outlet on a circuit different

from that to which the receiver is connected.

• Consult the dealer or an experienced radio/television

technician for help.

Caution: Any changes or modifications to this equipment not expressly approved by Texas Instruments may void your authority to operate the equipment.

This manual describes how to use the TI.80 Graphing Calculator. Getting Started gives a quick overview of its features. The first chapter gives general instructions on operating the TI.80. Other chapters describe its interactive features. The applications in Chapter 11 show how to use these features together.

Getting Started: Do This First!

Chapter 1: Operating the TI-80

Using this Guidebook Effectively Glossary

TI-80 Keyboard First Steps TI-80 Menus

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Entering a Calculation: Compound Interest Continuing a Calculation Defining a Function: Box with Lid Defining a Table of Values Zooming In on the Table Changing the Viewing Window Displaying and Tracing the Graph Zooming In on the Graph Other TI-80 Features

Turning the TI-80 On and Off Setting the Display Contrast The Display

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Entering Expressions and Instructions The Edit Keys Setting Modes TI-80 Modes Variable Names

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Storing and Recalling Variable Values Last Entry Last Answer TI-80 Menus The

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and

VARS

Y-VARS

EOS (Equation Operating System) Error Conditions

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Menus

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viii

xii

2 3 4 5 6 7 8

9 11 12 13 14

1-2 1-3 1-4 1-6 1-8

1-9 1-10 1-12 1-13 1-14 1-16 1-17 1-19 1-20 1-22

Introduction iii

Chapter 2: Math, Angle, and Test Operations

Getting Started: Lottery Chances Using the TI-80 Functions Keyboard Math Operations

MATH MATH MATH NUM MATH PRB ANGLE TEST

Operations

(Number) Operations

(Probability) Operations

Operations

(Relational) Operations

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2-2

2-3

2-4

2-7 2-10 2-12 2-14 2-16

Chapter 3: Fractions

Chapter 4: Function Graphing

Chapter 5: Parametric Graphing

Getting Started: Working with Fractions Setting Modes for Fraction Results Entering and Using Fractions in Calculations The

FRACTION

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Getting Started: Graphing a Circle Defining a Graph Setting Graph Modes Defining Functions in the Evaluating Selecting Functions Defining the Viewing Window Displaying a Graph

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List

Functions in Expressions

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Exploring a Graph with the Free-Moving Cursor Exploring a Graph with Exploring a Graph with Setting the Zoom Factors

Getting Started: Path of a Ball Defining and Displaying a Parametric Graph Exploring a Parametric Graph

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TRACE

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ZOOM

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3-2

3-4

3-6

3-8

4-2

4-3

4-4

4-5

4-7

4-8

4-9 4-11 4-12 4-13 4-15 4-18

5-2

5-3

5-6

iv Introduction

Chapter 6: Tables

Getting Started: Roots of a Function Defining the Independent Variable Defining the Dependent Variable Displaying the Table

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6-2

6-3

6-4

6-5

Chapter 7: Draw Operations

Chapter 8: Lists

Chapter 9: Statistics

Getting Started: Shading a Graph

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DRAW DRAW

Drawing Lines

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Drawing Horizontal and Vertical Lines Drawing a Function

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Shading Areas on a Graph Drawing Points Clearing a Drawing

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Getting Started: Generating a Sequence About Lists

LIST OPS LIST MATH

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Operations

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Getting Started: Building Height and City Size Setting Up a Statistical Analysis The

STAT

List Editor

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Viewing, Entering, and Editing Lists Sorting and Clearing Lists Statistical Analysis

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Types of Statistical Analysis Statistical Variables Statistical Plotting

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Statistical Analysis in a Program Statistical Plotting in a Program

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7-2

7-3

7-4

7-5

7-6

7-7 7-10 7-12

8-2

8-3

8-6

8-9

9-2

9-8

9-9 9-10 9-13 9-14 9-15 9-17 9-18 9-22 9-23

Introduction v

Chapter 10: Programming

Getting Started: Rolling a Die About TI-80 Programs

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Creating and Executing Programs Editing Programs

PRGM CTL PRGM I/O

(Input/Output) Instructions

Calling Other Programs

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(Control) Instructions

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10-2 10-4 10-5 10-6 10-7

10-11 10-14

Chapter 11: Applications

Chapter 12: Memory Management

Probability Experiments: Coins, Dice, and Spinners The Unit Circle and Trigonometric Curves Program: Newton’s Numerical Solve Routine Program: Numerical Integration

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Program: Window Variables Store and Recall Graphing the Inverse of a Function Graphing a Piecewise Function Graphing Inequalities

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Graphing a Polar Equation Program: Guess the Coefficients

Checking Available Memory Deleting Items from Memory Resetting the TI-80

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11-2 11-3 11-4 11-6 11-8

11-10 11-12 11-14 11-15 11-16

12-2 12-3 12-4

vi Introduction

Appendix A: Tables and Reference Information

Appendix B: Service and Warranty Information

Index

Table of TI-80 Functions and Instructions Menu Map TI-80 Variables

Battery Information Accuracy Information In Case of Difficulty Service and Support Information Warranty Information

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A-2 A-20 A-26

B-2

B-8 B-10 B-14 B-15

Introduction vii

Using this Guidebook Effectively

The structure of the TI-80 guidebook and the design of its pages can help you find the information you need quickly. Consistent presentation techniques are used throughout to make the guidebook easy to use.

Structure of the Guidebook

Page-Design Conventions

The guidebook is designed to teach you how to use the calculator.

Getting Started is a fast-paced, keystroke-by-keystroke introduction.

Chapter 1 describes general operation and lays the foundation for Chapters 2 through 10, which describe specific functional areas of the TI-80. Most chapters begin with a brief Getting Started introduction.

Chapter 11 contains application examples that incorporate features from different functional areas of the calculator. These examples can help you see how different functional areas work together to accomplish meaningful tasks.

Chapter 12 describes memory management.

When possible, units of information are presented on a single page or on two facing pages. Several page-design elements help you find information quickly.

Page headings—The descriptive heading at the top of the page or two-page unit identifies the subject of the unit.

General text—Just below the page heading, a short section of bold text provides general information about the subject covered in the unit.

Left-column subheadings—Each subheading identifies a specific topic or task related to the page or unit subject.

viii Introduction

InformationMapping Conventions

Specific text—The text to the right of a subheading presents detailed information about that specific topic or task. The information may be presented as paragraphs, numbered procedures, bulleted lists, or illustrations.

Page “footers”—The bottom of each page shows the chapter name, chapter number, and page number.

Several conventions are used to present information concisely and in an easily referenced format.

Numbered procedures—A procedure is a sequence of steps that performs a task. In this guidebook, each step is numbered in the order in which it is performed. No other text in the guidebook is numbered; therefore, when you see numbered text, you know you should perform the steps sequentially.

Lists with bullets—If several items have equal importance, or if you may choose one of several alternative actions, this guidebook precedes each item with a “bullet” (

Tables and charts—Sets of related information are presented in tables or charts for quick reference.

Keystroke examples—The Getting Started examples provide keystroke-by-keystroke instructions, as do the numerous short examples and several detailed examples that are identified with a

) to highlight it—like this list.



Introduction ix

Reference Aids

Several techniques have been used to help you look up specific information when you need it. These include:

A chapter table of contents on the first page of each chapter, as well as the full table of contents at the front of the guidebook.

A glossary at the end of this section, defining important terms used throughout the guidebook.

An alphabetical table of functions and instructions in Appendix A, showing their correct formats, how to access them, and page references for more information.

Information about system variables in Appendix A.

A table of error messages in Appendix B, showing the messages and their meanings and giving problem-handling information.

An alphabetical index at the back of the guidebook, listing tasks and topics you may need to look up.

x Introduction

Glossary

This glossary provides definitions for important terms that are used throughout this guidebook.

Argument

Command

Expression

Function

Home Screen

Instruction

List

Menu Items

An argument is an input upon which the value of a function depends.

A command is any entry submitted to the calculator using

. There are two types of TI-80 commands: instructions

and expressions.

An expression is a complete sequence of numbers, variables, functions, and their arguments that can be evaluated to a single answer. An expression returns the evaluated result to

ANS

A function, which may have arguments, returns a value and can be used in an expression.

A function is also the expression entered in the

editor used

in graphing.

The Home screen is the primary screen of the TI-80, where expressions can be entered and evaluated and instructions can be entered and executed.

An instruction, which may have arguments, initiates an action. Instructions are not valid in expressions. An instruction does not return a value to

ANS

A list is a set of values that the TI-80 can use for activities such as evaluating a function at multiple values and entering statistical data.

Menu items are shown on full-screen menus.

Introduction xi

Pixel

Real Number

Value

Variable

A pixel (picture element) is a square dot on the TI-80 display. The TI-80 display is 64 pixels wide and 48 pixels high.

On the TI-80, real numbers are individual decimal or fraction values.

A value is a single decimal or fraction number or a list of decimals or fractions.

A variable is the name given to a location in memory in which a value, an expression, a list, or another named item is stored.

xii Introduction



Getting Started: Do This First!

Getting Started contains two keystroke-by-keystroke examplesan interest rate problem and a volume problem operating and graphing features of the TI.80. You will learn to use the TI.80 more quickly by completing both of these examples first.

Contents

TI-80 Keyboard First Steps TI-80 Menus Entering a Calculation: Compound Interest Continuing a Calculation Defining a Function: Box with Lid Defining a Table of Values Zooming In on the Table Changing the Viewing Window Displaying and Tracing the Graph Zooming In on the Graph Other TI-80 Features

which introduce you to some principal

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2 3 4 5 6 7 8

9 11 12 13 14

Getting Started 1

TI-80 Keyboard

The keys on the TI.80 are grouped by color and physical layout to allow easy location of the key you need. The keys are divided into zones: graphing keys, editing keys, advanced function keys, and scientific calculator keys.

The Zones of the Keyboard

Graphing Keys

Editing Keys

Advanced Function Keys

Scientific Calculator Keys

Graphing Editing

Advanced Functions

Scientific Calculator

These keys are most frequently used to access the interactive graphing features of the TI-80.

These keys are most frequently used for editing expressions and values.

These keys are most frequently used to access the advanced functions of the TI-80.

These keys are most frequently used to access the capabilities of a standard scientific calculator.

& &

2 Getting Started

First Steps

Before beginning the two sample problems, follow the steps on this page to reset the TI-80 to its factory settings. (Resetting the TI-80 erases all previously entered data.) This ensures that following the keystrokes in this section produces the same actions.

1. Press ´ to turn the calculator on.

If the screen is very dark or blank, adjust the display contrast. Press and release 2, and then press and hold 8 (to make the display lighter) or press and hold 7 (to make the display darker). You can press

to clear the display.

2. Press and release 2, and then press µ. (Pressing

gives you access to the

printed at the upper left of the keys.

operation of the µ key.)

2nd

The

MEMORY

menu is displayed.

operations, which are

2nd

is the

MEM

3. Press 3 to select

The

4. Press 2 to select menu. The calculator is reset, and the

MEM CLEARED

RESET...

MEMORY RESET

RESET

message is displayed.

from the

MEMORY

menu is displayed.

from the

MEMORY RESET

menu.

Getting Started 3

TI-80 Menus

To leave the keyboard uncluttered, the TI.80 uses full-screen menus to display many additional operations. The use of specific menus is described in the appropriate chapters.

Displaying a Menu

When you press a key that displays a menu, such as

, that menu screen temporarily replaces the screen

where you are working.

fter you make a selection from a menu, you usually are

returned to the screen where you were.

Moving from One Menu to Another

menu key may display more than one menu name. The names appear on the top line. The name of current menu is highlighted, and the items in that menu are displayed. Use 9 or 6 to display a different menu.

Selecting an Item from a Menu

The number of the current item is highlighted. If there are more than seven items on the menu, a $ appears on the last line in place of the : (colon).

To select from a menu, you can either:

Use 8 and 7 to move the cursor to the item, and then press

Press the number of the item.

Note: The tenth item in a menu is number more than 10 items, they are numbered A, B, C, etc. To select one of these items, press letter.

Leaving without Making a Selection

To leave a menu without making a selection:

Press 2 . to return to the Home screen.

Press were.

Press the key for another screen or menu.

to return to the screen where you

. If there are

and then the

4 Getting Started

Entering a Calculation: Compound Interest

The TI.80 displays up to 8 16-characters lines so that you see an expression and its solution together. You can store values to variables, enter multiple instructions on one line, and recall previous entries.

Using trial and error, determine when an amount invested at 6% annual compounded interest will double in value.

1. For the first guess, compute the amount available at

the end of 10 years. Enter the expression just as you would write it. (Use 1000 for the amount.)

Press

1000

1.06

Z 10.

2. Press

to evaluate the expression.

The answer is shown on the right side of the display. The cursor is positioned on the next line, ready for you to enter the next expression.

3. The next guess should be greater than 10 years. Make

the next guess 12 years. To calculate the amount after 12 years, press

1000

1.06

, followed by

Getting Started 5

Continuing a Calculation

To save keystrokes, you can use the Last Entry feature to recall the last expression entered and then edit it for a new calculation. In addition, the next expression can be continued from the previous result.

1. The next guess should be less than, but close to, 12

years. Compute the amount available at the end of

11.9 years, using the Last Entry feature. Press 2, followed by

(the second function of

The last calculated expression is shown on the next line of the display. The cursor is positioned at the end of the expression.

2. You can edit the expression. Press 6 to move the

cursor over the

Press

. Then type

to change 12 to

1.9

to evaluate the expression.

Note: This process can be continued to obtain a solution with the desired accuracy.

3. You can continue a calculation using the result of the

last calculation. For example, if the final amount determined above is to be divided among seven people, how much would each person get?

To divide the last calculation by seven, press e followed by

As soon as you press e, beginning of the new expression.

is displayed at the

ANS

that contains the last calculated result. In this case,

contains 2000.505716.

ANS

11.9

is a variable

6 Getting Started

Defining a Function: Box with Lid

Take an 8½"×11" sheet of paper and cut X by X squares from two corners and X by (X+B) rectangles from the other two corners. Now fold the paper into a box with lid. What X would give the maximum volume V of a box made in this way? Use tables and graphs to determine the solution.

Begin by defining a function that describes the volume of the box.

From the diagram: 2X + A = W

2X + 2B = L V = A B X

Substituting: V = (W – 2X) (L à 2 – X) X

If necessary, press z †

MODE

. Then press y .

FLOAT

to change the

‘

return to the Home screen and clear it.

1. Press

¿ ƒ

8.5

to store the width of

the paper.

Press

¿ ƒ

to store the length of

the paper.

2. You define functions for tables and graphs on the

edit screen.

Press o to access this screen.

3. Enter the function for volume as Y1. Press £

¹ 2 @ ¤ £

to define function enter

quickly without pressing

L ¥ 2 ¹ @ ¤ @

in terms of X. (@ lets you

ƒ Í

The = sign is highlighted to show that Y1 is selected.

XABXB

Getting Started 7

Defining a Table of Values

The table feature of the TI.80 provides numeric information about a function. Use a table of values from the previously defined function to estimate an answer to the problem.

screen.

to accept

to define the table increment

(above

1. Press y

TABLE SETUP

2. Press

3. Press .5

4. Press y

Note that the maximum value is around

and 2.

(above

TBLMIN=0

) to display the

) to display the table.

, between

1.5

TBL=.5

5. Press and hold † to scroll the table until the sign

change appears. Note that the maximum length of for this problem occurs where the sign of

(volume) becomes negative.

6. Press y

. Note that

TBLMIN

has changed to

reflect the first line of the table you last displayed.

8 Getting Started

Zooming In on the Table

You can adjust the way a table is displayed to get more detailed information about any defined function. By varying the value of @TBL, you can “zoom in” on the table.

1. Adjust the table setup to get a more accurate

estimate of the maximum size of the cutout. Press

to set

TBLMIN

. Press .1 to set

Tbl

2. Press y

3. Use † and } to scroll the table. Note that the

maximum value displayed is

. The maximum occurs at

X=1.6

, which occurs at

33.072

1.5<X<1.7

Getting Started 9

4. Press y

Press

.01

. Press

to set

1.5

TBL

to set

TBLMIN

5. Press y

Two “equal” maximum values are shown,

X=1.58

6. Press † or } to move the cursor to

move the cursor into the of the display shows the value of precision,

and

33.073824

and use † and } to scroll the table.

33.074

X=1.59

. Press ~ to

1.58

column. The bottom line

1.58

in full

7. Press † to display the “other” maximum. The value

in full precision is

1.59

33.073908

. This would be the maximum volume of the box if you could cut your piece of paper at .01-inch increments.

10 Getting Started

Changing the Viewing Window

The viewing window defines the portion of the coordinate plane that appears in the display. The values of the Window variables determine the size of the viewing window. You can view and change these values.

1. Press

to display the Window variables edit screen. You can view and edit the values of the Window variables here.

The standard Window variables define the viewing window as shown.

XMIN, XMAX, YMIN

define the boundaries of the display.

, and

XSCL

YMAX

and

define the distance between tick marks on the X and

axes.

2. Press 0

to define

XMIN

3. You can enter expressions to define values in the window editor. Press

8.5

4. Press

5. Press 0

stored in

. The expression is evaluated, and

XMAX

. Press

to accept

to define the

XSCL

4.25

as 1.

Window variables.

YSCL

XMIN

YMAX

XSCL

XMAX

YSCL

YMIN

Getting Started 11

Displaying and Tracing the Graph

Now that you have defined the function to be graphed and the window in which to graph it, you can display and explore the graph. You can trace along a function with TRACE.

1. Press

to graph the selected function in the

viewing window.

The graph of

Y1=(W–2X)(Là2–X)X

is shown in the

display.

2. Press ~ once to display the free-moving cursor just to the right of the center of the screen. The bottom line of the display shows the X- and Y-coordinate values for the position of the graph cursor.

3. Use |, ~, }, and † to position the free-moving cursor at the apparent maximum of the function.

As you move the cursor, X- and Y-coordinate values are updated continually to reflect the cursor position.

4. Press

. The Trace cursor appears on the

function. 1 in the upper right corner of the display shows that the cursor is on

, you trace along

at each X.

, one X dot at a time, evaluating

. As you press | and

5. Press | and ~ until you are on the maximum Y value. This is the maximum of

for the X pixels.

Y1(X)

(There may be a maximum value “in between” pixels.)

12 Getting Started

Zooming In on the Graph

You can magnify the viewing window around a specific location using the Zoom instructions to help identify maximums, minimums, roots, and intersections of functions.

1. Press

to display the

ZOOM

menu.

This menu is typical of TI-80 menus. To select an item, you may either press the number to the left of the item, or you may press † until the item number is highlighted and then press

2. To

ZOOM IN

, press 2. The graph is displayed again.

The cursor has changed to indicate that you are using a Zoom instruction.

3. Use |, }, ~, and † to position the cursor near the maximum value on the function, and press

The new viewing window is displayed. It has been adjusted in both the

and Y directions by factors of

4, the values for Zoom factors.

4. Press

to display the new window variable

values.

Getting Started 13

Other TI.80 Features

Getting Started has introduced you to basic calculator operation and the table and function graphing features of the TI-80. The remainder of this Guidebook describes these features in more detail and also covers other capabilities of the TI-80.

Fractions

Graphing

Tables

Lists

Statistics

Programming

You can enter fractions directly from the keyboard and perform calculations with fractions. You can convert between fractions and their decimal equivalents. In

MANSIMP

mode, you can simplify fractions step-by-step. The TI-80 tells you when a fraction can be simplified and shows the common factor after simplification (Chapter 3).

You can store, graph, and analyze up to four functions (Chapter 4) and up to three parametric functions (Chapter 5). You can use Draw operations to annotate graphs (Chapter 7).

You can create function evaluation tables to analyze multiple functions simultaneously (Chapter 6).

You can enter and save up to six lists for use in statistical analysis. You also can use lists to evaluate expressions at multiple values simultaneously (Chapter 8).

You can perform one-variable and two-variable list-based statistical analysis, including regression analysis, and plot the data as histograms, points, x-y lines, or box-and-whisker plots. You can define and save three statistical plot definitions (Chapter 9).

You can enter and save programs that include extensive control and input/output instructions (Chapter 10)

14 Getting Started

Chapter 1: Operating the TI-80

This chapter describes the TI.80 and provides general information about its operation.

Chapter Contents

Turning the TI.80 On and Off Setting the Display Contrast The Display

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Entering Expressions and Instructions The Edit Keys Setting Modes TI.80 Modes Variable Names

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Storing and Recalling Variable Values Last Entry Last Answer TI.80 Menus The EOS (Equation Operating System) Error Conditions

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VARS

and

Y.VARS

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Menus

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1-2 1-3 1-4 1-6 1-8

1-9 1-10 1-12 1-13 1-14 1-16 1-17 1-19 1-20 1-22

Operating the TI-80 1-1

Turning the TI-80 On and Off

To turn the TI.80 on, press the ´ key. To turn it off, press and release y, and then press ®. After about five minutes without any activity, the APD™ (Automatic Power Down™) feature turns the TI.80 off automatically.

Turning the Calculator On

Turning the Calculator Off

APD™ (Automatic Power Down™)

Batteries

Press ´ to turn the TI-80 on.

If you pressed y ® to turn the calculator off, the display shows the Home screen as it was when you last used it, and errors are cleared.

If APD turned the calculator off, the display returns to the same screen or editor in which you left it. See “APD (Automatic Power Down)” below.

Press and release 2, and then press ® to turn the TI-80 off.

Any error condition is cleared.

All settings and memory contents are retained by the Constant Memory

feature.

To prolong the life of the batteries, APD turns the TI-80 off automatically after several minutes without any activity. When you press ´, the calculator shows the same screen or editor in which you left it.

If an error message was displayed when APD turned the TI-80 off, the error is cleared, and the display returns to a blank line on the Home screen.

If a menu was displayed, the display returns to the screen or editor from which you called the menu.

All settings and memory contents are retained by the Constant Memory feature.

Note: APD does not occur if a calculation or program is in progress, unless the program is paused.

The TI-80 uses two CR2032 lithium batteries. To replace the batteries without losing any information stored in memory, follow the directions in Appendix B.

1-2 Operating the TI-80

Setting the Display Contrast

The brightness and contrast of the display depend on room lighting, battery freshness, viewing angle, and the adjustment of the display contrast. The contrast setting is retained in memory when the TI.80 is turned off.

Adjusting the Display Contrast

When to Replace Batteries

You can adjust the display contrast to suit your viewing angle and lighting conditions. As you adjust the contrast setting, the display becomes lighter or darker. A highlighted number in the upper right corner changes to indicate the current contrast setting; 0 is the lightest, and 9 is the darkest.

To adjust the display contrast:

1. Press and release the 2 key.

2. Use one of two keys:

To increase the contrast (darken the screen), press and hold 7.

To decrease the contrast (lighten the screen), press and hold 8.

Note: The display may become completely blank if you adjust the contrast setting too low. If this happens, press and release

, and then press and hold 7 until the display reappears.

As you use the TI-80, the battery voltage will gradually drop, and the display will dim. You can adjust the contrast to darken the display when this happens. If the display is dim and adjusting the contrast to level 9 does not make it dark enough, you should replace the batteries. Refer to Appendix B for instructions on how to change the batteries.

Note: After you change batteries, the display contrast may appear very dark. Press and release y, and then press and hold 8 to lighten the display.

Operating the TI-80 1-3



The Display

The TI.80 displays both text and graphs. Graphs are described in Chapters 4 and 5.

Home Screen

Displaying Entries and Answers

Returning to the Home Screen

The primary screen of the TI-80 is the Home screen. You enter instructions to be executed, expressions to be evaluated, and see the results on the Home screen.

When text is displayed, the TI-80 screen can show a maximum of eight lines with 16 characters each.

If all lines of the display are filled, text “scrolls” off the top of the display.

If an expression on the Home screen, the Y= editor (Chapter 4), or the program editor (Chapter 10) is longer than one line, it wraps to the beginning of the next line.

On numeric editors such as the Window screen (Chapter 4), an expression scrolls to the left and right.

When an entry is executed on the Home screen, the answer is displayed on the right side of the next line.

Entry Answer

The mode settings (pages 1-9 through 1-11) control the way the calculator interprets expressions and displays answers.

If an answer is too long to display in its entirety, you can press

and 6 to scroll the answer so that you can view all of it. In the second example below, the open brace without a corresponding close brace indicates that the list is too long to be displayed in its entirety.

Entry Answer

Answer

Answer (scrolled)

To return to the Home screen from any other screen, press

y .

1-4 Operating the TI-80

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Texas Instruments TI-80 User Manual

Table of Contents

Using this Guidebook Effectively

Glossary

Getting Started: Do This First!

TI-80 Keyboard

First Steps

TI-80 Menus

Entering a Calculation: Compound Interest

Continuing a Calculation

Defining a Function: Box with Lid

Defining a Table of Values

Zooming In on the Table

Changing the Viewing Window

Displaying and Tracing the Graph

Zooming In on the Graph

Chapter 1: Operating the TI-80

Turning the TI-80 On and Off

Setting the Display Contrast

The Display