Manual / Guide · 1982
HP-75 Owner's Manual
Hewlett-Packard's owner's manual for the HP-75C portable computer (00075-90001).
Manual / Guide · 1982
Hewlett-Packard's owner's manual for the HP-75C portable computer (00075-90001).
HEWLETT-PACKARD HP-75 OWNER’S MANUAL WA we Sickne 17S NOTICE Hewlett-Packard Company makes no express or implied warranty with regard to the program material offered or the merchantability or the fitness of the program material for any particular purpose. The program material is made available solely on an “as is” basis, and the entire risk as to its quality and performance is with the user. Should the program material prove defective, the user (and not Hewlett- Packard Company nor any other party) shall bear the entire cost of all necessary correction and all incidental or consequential damages. Hewlett-Packard Company shall not be liable for any incidental or consequential damages in connection with or arising out of the furnishing, use, or performance of the program material. Printed in U.S.A. |G HEWLETT PACKARD HP-75 Owner’s Manual November 1982 00075-90001 Rev. B © Hewlett-Packard Company 1982 Preface The HP-75C is the first of a new generation of Hewlett-Packard portable computers that provides the power and sophistication of a high-level language computer, combined with a truly portable computer system. The HP-75C has 16K (16,384) bytes of Random Access Memory (RAM) available to store user created programs, text, and variables. It also has 48K bytes of read-only memory (ROM) dedicated to its operating system. How to Use This Manual This manual was designed as both a learning and a reference tool. At first, you will use it to learn how your computer functions and to become familiar with all of its capabilities. Although your HP-75 was designed to be easy to use, because of its power and sophistication you'll need to invest some time in this learning process. After you learn to use your computer, the manual will serve as a comprehensive reference to every aspect of your computer’s operation. Part I of the manual, Welcome to the HP-75!, introduces you to the HP-75 and provides you with the information you need to start using your computer. Read part I first—it should only take a few hours to read the instructions and work through the examples, After completing part I, you should be able to turn the HP-75 on and off; enter and run a prerecorded BASIC program; use the keyboard to control the display; and edit and manipulate text and BASIC files in memory. Part II, Using the HP-75, describes in detail all of the major features of the HP-75. Some of the sections in part II describe features that you may not need or want to use at this time. Feel free to skip over those sections and read only what you need. After finishing part II, you should be able to do keyboard calculations using operators and functions; use, set, and adjust the system clock; set and acknowledge appointments; perform card reader operations; use the built-in HP-IL interface; and redefine the keyboard. Part III, Programming the HP-75, explains how to program the HP-75 in BASIC. It’s written for those who have had some programming experience in BASIC or another high-level language. If you’re new to programming, you may wish to study one of the many books available on beginning BASIC programming before starting part III. After completing part III, you should be able to write, edit, run, and correct BASIC programs using all of the system commands and BASIC statement available on the HP-75. The appendices at the back of the manual provide valuable reference material. Appendix G, Glossary, defines many of the terms used in this manual—you may wish to refer to it early in your study of this manual, Appendices C, D, E, and H contain the principal reference information about the operation and programming of the computer. Appendix B contains information about caring for and obtaining service for your computer and appendix A contains a list of all of the standard accessories you received with your computer. Finally, appendix F contains listings of all of the programs in your Owner's Pac. Two indexes are provided in this manual. A comprehensive subject index and, inside the back cover, a complete index to the HP-75 instruction set. The index to the instruction set will allow you to quickly locate the principal page reference for all of the commands, statements, functions, and operators in your computer. The HP-75 Reference Manual that accompanies your HP-75 lists the instructions and operations of the computer in condensed form. It’s compact enough to keep with your HP-75 wherever you take it. You can use the reference manual as a ready reference after you have completed part I of the manual and while studying parts II and III. The HP-75 Portable Computing System The HP-75 is designed so that it can be used as the controller of a portable computer system. The built-in HP-IL interface allows you to connect the HP-75 to a wide range of peripherals for increased computing power. The three plug-in ports on the front edge of the HP-75 provide access for modules containing additional commands and BASIC statements as well as a variety of applications programs. Be sure to check the accessory brochure included with your computer to learn about Hewlett-Packard peripherals and software products that extend the capabilities of the HP-75. Contents HP-75 Keyboard .............. ccc eee cece ccc cette eee e eee e eee e er en resets ete eteteetee 6 HP-75 Display Templates .................c ccc ce ccc eeer et ret bette eens eee eneeee 6 PartI: Welcome to the HP-75! Section 1: Getting Started 22.2.0. 0.0.0.0 ccc ccc een eee t eee e tenn enn eens 10 Introduction—The Three Operating Modes—-TIME Mode—APPT Mode—EDIT Mode—The Modifier Keys—General Information—What's Ahead—Syntax Guidelines Section 2: Keyboard and Display Control ............... 0.005000. cece cece eet e et eeee 34 Introduction—The Keyboard—The Editing Keys—Displaying Information—The HP-75 Character Set—Advanced User's Information Section 3: File Editing ................ ccc cece tte tect e eet e been ener eee 44 Introduction—Filenames—Files in Memory—EDIT Mode—Available Memory—Creating and Editing a File—Checking the System Catalog—Purging Files—Entering Lines in a Text File Editing Operations—File Manipulations Transforming Files—Command Summary PartII: Using the HP-75 Section 4: Keyboard Calculations ....................0cce cere ee . 68 Introduction—Arithmetic Operations—Multiple Calculations—The Last Result- “Arithmetic Hierarchy—Parentheses—Numeric Precision—Number Formatting—Range of Numbers Section 5: Numeric Functions and Expressions .............000ceeeeereee cence eee eenees 78 Introduction—Variables—-Naming Simple Numeric Variables—Assigning Values to Variables-—Precision of Numeric Variables—Calculator and Program Variables—Numeric Functions—Numeric Expressions—Relational Operators—Logical Operators—Precedence of Operators—Recovering From Mathematical Errors Section 6: TIME Mode Operations ... . 92 Introduction—Clock Operation—Changing to Day\Month\Year and 24-Hour Formats— Adjusting the Clock—Clock Functions Section 7: APPT Mode Operations ... Introduction—Scheduling Appointments—The File—Deleting Individual Appointments—Editing Already Scheduled Appointments—Processing Due Appointments — Turning Off APPT Mode—Appointment Types—Command Appointments—New APPT Templates—The Extended Calendar—Copying Appointments To and From Mass Storage .114 Section 8: Card Reader Operations .. Introduction—-HP-75 Magnetic Cards—Using the Card Reader—Specifying Card Files— Cataloging a Card—From Memory To Card—From Card To Memory—Protecting Card Files— The Three P's of Protection Section 9: HP-IL Operations .. Introduction—Connecting the Hewlett-Packard Interface Loop—Assigning Device Codes— Listing Device Assignments—Declaring Display and Printer Devices—Displaying and Printing Information—Turning the Loop Off and On—Transmission Interruptions—Clearing Devices—Mass Storage Operations—Advanced User's Information Section 10: Redefining the Keyboard ................. 0.066000 ccc cece cece eee tent eens 142 Introduction—Typing Aids—The |: «=: File—Undoing Key Redefinitions—Immediate- Execute Keys—Fetching Key Definitions—TIME and APPT Modes—Multiple Key Operations—Multiple Keys Files—Copying Keys Files To and From Mass Storage— Advanced User's Information Part III: Programming the HP-75 Section 11: Programming Fundamentals . Introduction—Writing and Editing Programs—The «- Program—Running Programs— Initializing Programs—Interrupting Programs—Examining Programs—Definitions— Multistatement Lines—Program Variables—Fundamental Statements—Th Program—Using File Commands With Allocated Programs—Thi : Turning the HP-75 Off—Errors Section 12: Branches, Loops, and Subroutines .. . 176 Introduction—Unconditional Branching—Conditional Branching—Looping—: ~ Subroutines— The Computed ‘3:1 F<“) Statement—The Computed (1/5118 Statement—Bypassing a Pending Subroutine Return—Program Timers Section 13: Arrays, Strings, and User-Defined Functions ..............0....000e00 ee 192 Introduction—Setting the Lower Bound—Declaring Arrays—Assigning Values to Arrays— String Expressions—String Functions—String Expression Comparisons—The *.! 7 Statement—Simulating String Arrays—User-Defined Functions Section 14: Storing and Retrieving Data .................. Introduction—Reading Data Within a Program—Rereading Data—The ! Program—Creating and Accessing Data Files—Storing Data Ina File—Reading Data Froma File—Closing Data Files—Serial and Random Access—Special Forms of # ¥ | Hand #—Moving the Data Pointer—Statement Summary—Storing and Retrieving Arrays—Accessing Text Files—The F } | T Program—Long Data Lines Section 15: Program Calls ......... 0.00.0... cece ence eee cece ence e tee beet eet ee neanees 230 Introduction—Calling Programs—Comparing Programs—Passing Values Between Programs—Global and Local Declarations—Recursive Calls Section 16: Display and Printer Formatting ............... ccc cece cece eseee rece eaneeees 238 Introduction—Using 1! —Delimiters—Blank Spaces—String Specifications—Numeric Specification—Compact Field Specifier—Replication—Reusing the [mage Format String— Numeric Field Overflow—Formatting in {| Mis and PR LH Statements—Image Format Summary F Section 17: Debugging Operations ........... 0... cece eee een eee etree eect nee eee eens 252 Introduction—Tracing Program Execution—Single-Step Execution—Checking a Halted Program—Processing Run-Time Errors—Error Numbers and Lines Appendices Appendix A: Accessories Included With the HP-75 Appendix B: Owner’s Information .................. 0.20 ccc ee eee ete eee e teen teens Appendix C: Keyboard Operations 2.0.0.0... 0. ccc ccc cece cece eee e eee e ene neeteenneeee Appendix D: Reference Tables ........................ cece cece cee cece eee teen eee Appendix E: Error Conditions ...........0.0 02.0000 c ccc cece cette eee e teen eee eennnnees Appendix F: Owner’s Pac Program Listings ..................c cece cece eee e eee ees Appendix G: Glossary ............ cece eee eee rere eee e ere n een een rene ene ee rene ee eee Appendix H: Syntax Summary ........... 0.0.6 c ccc ccc eee e eee n eee ee en seen rene enneenes Subject Index ................ cece eee eee en ren rer ree eee eben reer eens 350 HP-75 Instruction Set Index ..... 0... cece eee ee tect ee eet eens Inside back cover HP-75 Keyboard [6 Bees 2 x ic vs ty ow ts sis System keys are black; editing keys are shaded. HP-75 Display Templates Where the i@ cursor symbol appears over another character, the cursor is shown as a shaded block behind the character. TIME Mode HYP OBESGS+1 983 85:30:15 AM Ee Typical TIME display. Mo-OyeYear Hritini Sc AR Set-time template. Used to set the clock. HOY. Time: AM ipp es YERR TATS template. Used to specify date and time formats and to change the range of the appointment calendar. id just ¢No & Hr+hineSe.t ACJ T template. Used to adjust the clock setting. May MoeDyeYr Health AM HIN i Note APPT template. Used to schedule appointments. Repeat template. Used to set repeating appointments. sar Yt Year template. Used to schedule extended calendar appointments. EDIT Mode a] EDIT mode display showing the BASIC prompt and cursor, :E EDIT mode display showing the text prompt and cursor. The first line of a 157 i. listing. A BEE L AES Typical file catalog. A default key definition. BASIC program statement. For displaying the file catalog of a magnetic card. Copy te A CETHI For copying a file from memory to a card. Verify card TRTRI For verifying the accuracy of information transferred to a card. Copy from card Alien & CRTRI For copying information from a card to memory. CRTWI For protecting a magnetic card from erasure. Alien & CRTKI For removing a card’s write-protection. Hewlett-Packard Interface Loop fewiee 4 Ls * i Displayed at the beginning of HP-IL device assignments. 7/8 Part I Welcome to the HP-75! Section 1 Getting Started Contents Introduction .......... 0c cece c cece e eee ence eee e sneer You Can't Damage the HP-75 by Pressing Its Keys . Using the AC Adapter/Recharger ............ 6006s cece eect c ec e eee nee ete ete e ee ee teen eens Turning the HP-75 ON ( Turning the HP-75 Off Resetting the HP-75 ( The Two Most-Used Keys ( : The Display Window ........ 0... cece cece eee eee ee ene see e eee bese essen tenets eeeeeseeeeee The Three Operating Modes ......... 0.0... c cece eee e cence eee ee ee ees ees eset ees eeseesteeeeeees TIME Mode ( [TIME] APPT Mode ({APPT]) ............. Scheduling an Appointment ([TA When an Appointment Arrives ((APPT],(ATTN]) 0.2... 0.000 ccc c cece cece cence eee ee eens eenees EDIT Mode ((EDIT}) Keyboard Arithmetic Typing in Edit Mode (* ‘ Any Trouble ([SHIFT][FET], [CLI Writing and Running a BASIC Program { Copying a Prerecorded Program ('~ Running a Prereco Redefining a Key Typing a Memo (§ i J Controlling HP-IL Devices The Modifier Keys ( The Shifted Keyboar The Numeric Keypad ( Special Display Characters General Information . Locking the HP-75 Keeping the HP-75 O1 The Beeper (£ Keyword Abbreviations ((*]) .. What's Ahead ...............4. a Syntax Guidelines ........ 00... cece ccc eee eee e eee tee tenet ee eee teen eens Introduction Congratulations on your purchase of the HP-75 Portable Computer! In order for you to start using the HP-75, there are several things you need to know right away. You Can’t Damage the HP-75 by Pressing Its Keys You use the 65-key keyboard to interact with the HP-75. Many keystroke combinations are possible. By pressing a wrong key, you may cause an error message to appear or even erase the contents of memory, but you can’t damage the HP-75 by pressing its keys. 10 Section 1: Getting Started 11 Using the AC Adapter/Recharger When you receive your HP-75 the rechargeable battery pack will already be installed in the computer. The battery pack may, however, be discharged initially. If it is you can operate the HP-75 immediately by using the ac adapter/recharger included with your unit. To correctly install the ac adapter/recharger: Note: While the ac adapter/recharger is being plugged into the case of the computer or being unplugged, it’s desirable to have the HP-75 turned off. If the HP-75 display is on, refer to Turning the HP-75 Off (page 13). 1. Insert the adapter plug into the adapter receptacle on the back edge of the HP-75. 2. Insert the power plug of the ac adapter/recharger into an ac power outlet. These two steps may be reversed. Also, the ac adapter/recharger can be disconnected whenever you want to operate the unit from the battery pack. Although the HP-75 may be operated from a power outlet with the battery pack removed, the contents of memory may be lost due to any outlet disconnection or line voltage variation. It’s normal for the ac adapter/recharger and the door of the battery compartment to be warm to the touch when the HP-75 operates from an ac outlet. Turning the HP-75 On ((ATIN)) What Happens At Power On. If the battery is charged or the ac adapter/recharger is plugged in, press the (attention) key to turn the computer on. You'll see one of two different displays: Set MoeluevYeae Hein Se AA The set-time template. or >i The edit mode cursor. 12 Section 1: Getting Started Tf you see the first display above, the HP-75 is signalling you to set the system clock. Skip down through this section to Setting the System Clock and continue reading from there. Tf you see the second display above you need to examine the TIME display so you can check and if necessary, reset it. Press the [TIME] mode key on the upper left part of the keyboard. You will see a display that looks like this: SAT GE-85-82 85:18:17 AM i TIME display. The date and time you see will, of course, be different from the one shown. If the date and time are the correct ones, you don’t need to complete the steps in the rest of this section. If the date and time are incorrect, type the word “set” and press (return) key. Now you will see the very first display shown above—the set-time template: Beelyeear Heidi Se AM The set-time template. Setting the System Clock. The set-time template contains all the information you need to set the system clock. The replace cursor, il, is a steadily blinking rectangle that moves across the display as you type. (This manual uses a shaded block behind the character to indicate the cursor symbol when the cursor appears over another character in the display.) Use the row of numbers on the keyboard to type the date and time information. In the set-time template above, the first digit you type will replace the "| in ! (month). If you make a mistake, press the (backspace) key or (CLR) (clear) key and continue typing. Pressing allows you to start over. Supply this information in the TIME display: The current month. Specify a number from £1 | (for January) through ! | (for December). Be sure to use the [0) key when you type a zero (§) rather than the (0) key.* The day of the month. Specify a number from “1 through 3. The year, a four-digit number. The hour, a number from i i through : =. The minute, a number from “ii through =>. The seconds, a number from ‘ii through “3. Set the seconds to a time that is approaching but still about 45 seconds away * For the month, day, hour, minute, and seconds fields, you may use a space instead of a zero. For example, "1", space“, and © space in the month field all specify June. Section 1: Getting Started 13 AM The display after the above information has been typed. In the examples, “today” begins on Saturday, February 5th, 1983, at 9:00 AM. Type an 4 for = for Pl), Finally, at the specified time press the (return) key. The key sets the clock to the displayed time about 0.1 seconds after it’s pressed. Note: Throughout this manual, side-by-side displays, such as the one that follows, show information to be entered (on the left) and the result after pressing (on the right). The completed template. The day-of-week is automatically computed, and the TIME display is updated every second. The HP-75 uses the system clock for many of its operations, which include scheduling appointments, dating files, and running programs. Turning the HP-75 OFF ( ) The [ATTN] key is the on button of the HP-75; pressing it turns on the display and activates the keyboard. To turn the computer off, hold down the [SHIFT] key, then press the key and immediately release both—after a short delay (about one second) the display will turn off and the keyboard will become inactive. The HP-75 uses power continuously to maintain system memory and operate the clock. Power consumption is higher when the computer is active (display on) and lower when it is inactive (display off). To conserve power, the HP-75 turns itself off after about 5 minutes of idleness. No matter how the computer is turned off, by you or by itself, the [ATTN] key will turn it back on. Resetting the HP-75 ([S (ctR]) A reset causes the HP-75 to lose everything in memory and return to the ready state when the battery pack was first installed. There are three ways to reset the HP-75: e Let the battery pack become completely discharged. e Take out the battery pack while the unit is not connected to an ac source and while the display is on. The RAM circuits become discharged immediately. e Reset the HP-75 from the keyboard using a three-key keystroke. You hold down the key and [CTL] (control) key while pressing the key for approximately 1 second.* If you ever choose to reset the machine, you'll need to start all over by pressing [ATTN] and setting the system clock. Try CTL now if you’d like, but in the future it shouldn’t be necessary. To remove the battery pack without causing a machine reset, first turn the HP-75 off (press [SHIFT] [ATTN]) before sliding the battery door off. Don’t press [ATTN] while the battery pack is out of the compartment. If the unit isn’t connected to a power outlet, don’t leave the battery pack out of the compartment for longer than 30 seconds. Refer to appendix B for more battery information. * In addition to SHIFT](CTL](CLR], the following keystroke combinations also cause a system reset if held for one second or longer: [SHIFT |[CTL followed by (I7R), [8], 2, (3), or [M). 14 Section 1: Getting Started The Two Most-Used Keys ( (ATTN), [RTN]) The [ATTN] key has been placed in the upper-left corner for good reason—it’s important. In effect, it interrupts almost all system operations and readies the HP-75 for your next keyboard entry. While the key alerts the HP-75, the key puts it to work. When you press [RTN], one or more of the following happen: e The contents of the display are stored in memory, as happened when you set the clock. e Thecommand or calculation you've just typed is executed. e The HP-75 informs you of an error by beeping and lighting an error indicator in the display window. You can recover from most errors by pressing the key. Knowing when to press [RTN)—and when not to—means that you’ve learned to control the HP-75, You should be at this point when you've finished section 3, File Editing. The Display Window The display window shows 32 characters at a time. Each display line holds up to 96 characters including the cursor. When you type a message that completely fills the 32 character window, entering more characters causes the message to scroll left across the display. The display window contains four annunciators, or status indicators, that tell you about special operating conditions. BATT ERROR PRGM APPT Usually invisible, they appear when: BATT: Battery voltage is low. ERROR: The HP-75 doesn’t understand one of your instructions or has encountered a mistake during a program. PRGM: A program is currently running. APPT: An appointment has come due. The Three Operating Modes Pressing any one of three keys—[TIME], [APPT] (appointment), or [EDIT]|—causes the HP-75 to switch to the specified mode or operating state. TIME mode is used for: e Setting the system clock. e Displaying the time. e Specifying new time and date formats. e Adjusting clock speed. APPT mode is used for: e Scheduling personal and business appointments. e Checking calendar dates. Section 1: Getting Started 15 EDIT mode—the “workhorse” of the three—is used for: e Doing keyboard calculations. e Writing and running BASIC programs. e Copying information to and from magnetic cards. e Redefining individual keys and keystroke combinations to display messages and execute commands. e Writing memos. e Controlling Hewlett-Packard Interface Loop printers and other HP-IL peripherals. Press each of the three keys now: (TIME): Switches the HP-75 to TIME mode. ite Switches the HP-75 to APPT mode. (EDIT): ii Switches the HP-75 to EDIT mode. The capabilities of all three modes—TIME, APPT, and EDIT—will be briefly introduced in this section. TIME Mode ([TiMeE}) The HP-75 enters TIME mode when you press the [TIME] key. You can set the clock to a different time by typing the word “= ' in the TIME display and pressing the key: The set-time template appears. Press to cancel this procedure, or type in the new information and press [RTN]. If you omit any information (like the month, day, or year), then it’s supplied from current date and time values. The use these commands to specify new display formats and adjust the clock. The examples in this manual usually show month/day/year and AM/PM formats. ‘Y command is one of five TIME mode commands. Section 6, TIME Mode Operations, explains how to Note: As you're reading this manual, the display may go blank—remember that this means the HP-75 has turned itself off. Press [ATTN] to turn the HP-75 back on. The computer will always turn on in EDIT mode. 16 Section 1: Getting Started APPT Mode ([APPT]) The HP-75 comes equipped with two calendars—a year calendar and an extended (10,000-year) calendar— that allow you to schedule alarms, messages, and programs. APPT Mode combines the accuracy of the HP-75 clock with the capability of the HP-75 microprocessor. It’s possible to schedule more than 3000 different appointments on the HP-75C, and each appointment can keep repeating itself at intervals from 1 minute to 8 years. Scheduling an Appointment ( (TAB), [BACK], (], (RTN)) To schedule an appointment, switch the HP-75 to APPT mode—press [APPT]. The APPT template appears: The type of appointment. The note or command indicator. field. YY The beginning of the 68-character != # eel The type of audible alarm. The time. The date. The day-of-week. These fields, or display areas, are explained in detail in section 7, APPT Mode Operations. For now, here are the keys that help you schedule appointments: e The key causes the cursor to skip forward across the APPT template. Also, causes the cursor to skip backwards. e The , (=) (left-arrow), and [+] (right-arrow) keys let you make changes in what you've typed. e The key clears the line and restores the APPT template. For this example, press the key six times to skip to the { in the alarm field. Then press (3) to set a two-tone alarm pattern: fag Moola r Heofin AM BBN PA The APPT template after you’ve specified the type of alarm. Ten types are available (page 101). Press once more to move the cursor to the start of the «i ¢ @ field. When the appointment comes due, your note will appear with it. We use a short note: Finonme Jim: iii AM HEN TF Your appointment message may contain up to 68 characters—more than two full display windows. The ([+]and [+] keys let you review the completed appointment. When the appointment is typed the way you want it, press (RTN], which stores the appointment in memory. The completed appointment is echoed: The sample appointment is scheduled to go off at the beginning of the next minute. Section 1: Getting Started 17 You don’t have to fill in the APPT template completely because the HP-75 calculates values for the fields you leave blank, based on current date and time values and on the values you do supply. Note that the cursor skips the ' (year) field altogether; the HP-75 is set to the year calendar, so supplying year information is unnecessary if your appointment falls before the end of the next calendar year. Press to display the unfilled APPT template. When an Appointment Arrives ( (APPT), [ATTN]) Whether you’re in TIME, APPT, or EDIT mode, when an appointment arrives, the alarm sounds and the key to check the time while waiting for the , you'll see: APPT annunciator turns on. For this example, press the [T! appointment to come due. When the seconds counter reaches aM During TIME mode, an appointment comes due, ApeT sounding the alarm and turning on the APPT annunciator. Pressing brings the due appointment to the display: ‘The day-of-week, date, and time are underlined, signifying that this is a due appointment. Press [ATTN] to acknowledge the appointment and to turn off the APPT annunciator. Use the [t] (up-arrow) and (4](down-arrow) keys to review earlier and later appointments—they’re stored according to their arrival times. If an appointment comes due after the the HP-75 has turned off, then the HP-75 sounds the alarm, turns on in EDIT mode, and displays the note. To see this, turn the machine off—press When the HP-75 is turned off, it processes due appointments and past due appointments. In this case, the HP-75 displays the appointment note. The note is held in the display for 5 seconds or until you press any key; afterwards, the HP-75 turns itself off. When you turn the machine back on (press [ATTN]), the APPT annunciator will appear if there are any appointments waiting to be acknowledged. Besides displaying notes, appointments can be scheduled to run programs and to execute other programming statements. Refer to section 7 for more information. EDIT Mode ((EDIT]) EDIT mode is the powerhouse of the HP-75. Practically all HP-75 operations are performed in EDIT mode. When the machine is turned on, or when the [EDIT] key is pressed, the HP-75 switches to EDIT mode. > A The display indicates EDIT mode. The BASIC prompt, a * symbol, appears at the left edge of the display line and indicates that the HP-75 is ready for your next command, program statement, or keyboard calculation. There is also a text prompt, a : (colon), that is used while you type memos and other correspondence. To get the BASIC prompt or the text prompt in the display—if it isn’t there already—you follow these steps: 1. Press (EDIT). 2. Type urae and press [RTN]. The * = command erases the computer’s current workspace. 18 Section 1: Getting Started 3. Choose one: * and press [RTN]: e For the text prompt ( :), type The display shows the catalog entry of a temporary text work File, :: and press (RTN]: The display shows the catalog entry of a temporary BASIC work file. The time of the file’s creation is expressed in 24-hour notation; for example, 1 p.m. is displayed as A i5 indicates the file is empty. 4. Press [ATTN]. The appropriate prompt will appear: :H The text prompt. >Hi The BASIC prompt. The meaning of these steps will become apparent in section 3, File Editing. Keyboard Arithmetic ((+] ) The HP-75 serves as a powerful calculator in EDIT mode, equipped with 64 built-in functions and operators. You should have the BASIC prompt (*) in the display for keyboard calculations. (Refer to the preceding topic if the text prompt is there instead.) To add a series of numbers, type in the expression and press[RTN}. Example: An equals sign (=) is not used for keyboard Pressing the key returns the answer. arithmetic. The period ( . ) serves as a decimal point. Other arithmetic operators besides addition include subtraction (—), multiplication (*), division (.”), and exponentiation (“). You can evaluate any combination of integers and decimals, using whatever operators you need. The HP-75 calculates to 12-digit precision. Section 4 details the use of the HP-75 for keyboard arithemetic. To take the square root of a number, say 78, type the following and press (RTN): When typing the function, the prompt The answer. Rounding occurs at the least reappears as soon as you press the(S] key. significant (12th) digit. Numbers, functions, and variables can be combined with arithmetic operators (such as +), relational operators (such as *), and logical operators (such as ) to form complex expressions. Section 5 discusses HP-75 numeric functions and expressions. Section 1: Getting Started 19 Typing in EDIT Mode (' ' and “") When the BASIC prompt (*) is present, the HP-75 treats the lowercase letters in your entries the same as capital letters. This means you can use either lowercase or uppercase letters—whichever are easier—to type your commands and programs. The examples in this manual use mostly lowercase letters. In EDIT mode, the HP-75 generally disregards the spacing of your entries so that you can use as many or as few spaces as you choose, except that the first two characters on a line must appear with no spaces between them, and consecutive digits of a number must have no spaces between them. Example: Arbitrary case and spacing. When you press , the square root of 64 is computed. You can preserve spaces and lowercase letters by enclosing your entries with quotation marks. It makes no difference whether you type single quotes (‘ ', produced by (7) or double quotes (*", produced by ), as long as they match. Within pairs of quotation marks, characters are interpreted exactly as you type them.* Example: Semicolons separate the three quoted strings. Pressing causes the strings to be echoed as typed. This manual generally uses single quote marks (‘ ‘) to delimit, or set off, strings of characters. A typing convenience is the repeating keyboard: Holding down any character key or keystroke combination causes the key display character to be repeated after a short delay. For example, the [B] key: Holding down [B] produces three windowsful of !:’s. The line begins scrolling when the cursor reaches the right edge of the display. System keys (like [TIME]) and editing keys (like [TAB] ) also repeat their functions when held down. The first display position is reserved for the prompt; the last, or 96th, position, is reserved for the cursor. This means that you may type 94 characters in each line. The HP-75 beeps when you type the 91st character—you can type three more characters before the cursor stops at the end of the line. Any Trouble? ((SHIFT)[FET], [CLR], [ATTN], If the HP-75 beeps and turns on the ERROR annunciator while you're typing, the computer is signaling that it’s tried unsuccessfully to interpret a command or an input or that it’s attempted an improper operation. The word SS or 4 i! and a brief message will appear in the display and, usually, what you’ve just typed will be recalled to the display. For example, press [CLR], type an incorrect expression, and press [RTN]: * Exceptions are filenames, that is, quoted names that specify the files in memory. User filenames are converted to uppercase in the system catalog (page 45), 20 Section 1: Getting Started extra characters ERROR The multiplication operator is %, not *. The HP-75 response. The error message stays in the display for about 1 second. Afterwards, the original expression is recalled: The cursor returns to the position where the HP-75 ERROR first detected an error. means that the HP-75 is unable to interpret the characters after , the The message #f fa oc Fact last meaningful character in the line. There’s no need to worry if an error occurs—no keyboard or program operation is capable of damaging the system. You've got several options: View the Error Message Again. Hold down while pressing the [FET) (fetch) key and keep the [FET] key down. Example: extra och 7 § Pressing ERROR message. displays the current error Correct the Display. Use the line editing keys (in this case, the [=] key), to reposition the cursor and then type the necessary corrections: ERROR The corrected line. After typing the #, press . The expression is interpreted correctly as 2 + (6 * 3). (Multiplication occurs before addition unless you change the order with parentheses.) Clear the Display. Press the or [ATTN] key and then retype the entry. Once the ERROR annunciator disappears, the error condition is cleared. Afterwards, pressing T] displays a blank line. View the Error Number. Each error has an identification number as well as a message. The ! function returns the identification number of the error which occurred most recently: returns 84, the number associated S oharacters error. with the Appendix E is a table of error numbers, messages, and conditions. Use the + function to locate a specific entry in the table. An error may cause either an i » message to appear. The difference is that an error condition will halt a running program, while a warning condition will cause a default (or predetermined) value to be supplied and allow program execution to continue. This manual refers to both errors and ora warnings as errors except where noted. Section 1: Getting Started 21 Writing and Running a BASIC Program ([RTN], [RUN], [ATTN]) The BASIC prompt in EDIT mode indicates the computer's readiness to accept BASIC program statements. Here’s a one-line “random music” program for you to enter and run. Press and type the following: b1 beep rr * Hi ‘Two program statements are joined in one line. Pressing stores the program line in memory. Spacing isn’t important. Press the [t] key to review the program: vid eMEDE SS &@ GOTO 4 The HP-75 has converted the letters to uppercase and corrected the spacing for readability. Now press ° run followed by a to clear the display. To run the random music program, press the key or type . To stop the program, press [ATTN]. Notice that the ! ‘| annunciator appears in the display window to indicate that a program is running. Except for [ATTN], the keyboard is disabled during program execution to prevent unintentional disruption. After you've stopped the program, give it a filename using the 4£ command. Type: gives the current program a name, converted internally to uppercase. it Pressi Copying a Prerecorded Program ( One of the functions of the ! ‘*’ command is to copy prerecorded programs from magnetic cards into memory. An example is the HP-75. Find and remove the two !*") -* program, one of the three prerecorded programs included with your ** magnetic cards from the card holder shipped with your unit. CAUTION Handle magnetic cards by their edges to avoid contaminating the sensitive magnetic surface and the card reader head. Card cleanliness is important for proper card reader performance. Never pass a magnetic card through a strong magnetic field. Such action will render the card totally unusable. Protect your magnetic cards against scratches, creases, and dirt by replacing them in the card holder as soon as possible after use. 22 Section 1: Getting Started Dopey from card: Hiian & The command specifies the filename you want for The response shows the HP-75 is ready for a card the program. Press . reader operation. If you want, you can cancel the card reader operation now by pressing . Otherwise, the HP-75 waits for you to insert a card and to press the key. Each magnetic card may store information on two tracks. To copy the information on a full card, you'll need to copy the card in both directions. The order of the cards and the number of repetitions are immaterial. Insert a card printed side up, either edge toward you, and gently slide it in the direction of the card reader arrow. Keep inserting the card until the rightmost alignment mark is under the entry slot and the alignment mark to its left remains exposed. About 1 cm (%-'4 in.) of the end of the card should protrude from the exit slot. With the card aligned in the card reader, press [RTN]. The display will show: Pull card ... Ready for the first pass. Grasp the right end of the card between your right thumb and index finger and pull smoothly and steadily. A pull through the card reader should take about as long as it does to say the name ‘“‘Hewlett-Packard.” The speed of the card may range from 13 to 76 cm/second (5 to 30 in./second). It may be helpful to do a few trial pulls to search for the lower and upper speed limits. You may pull the same track through the card reader an unlimited number of times. The HP-75 display indicates immediately whether or not the pass has been successful. Examples: st Indicates you’ve pulled the card too fast. Section 1: Getting Started 23 Indicates that track 2 has been read and the card may be turned around for reading the other track. Indicates that the card was not read correctly. If this warning occurs repeatedly, you should clean the card (refer to appendix B). After the message is displayed, you'll again see: Alian & £RTHI Indicates you may insert the same track or another track from the same program. Press before each pull. The HP-7