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¢@¢B Programmer's Calculator Version 1.0 Copyright 1983 Ronald Moak Forest Computer Consultants P.O. Box 1463 Springfield, Oregon 97477 All rights reserved TABLE OF CONTENTS STARTING UP INTRODUCTION . . . . . . . . . . .1 SYSTEM REQUIREMENTS. . . . . . . .2 BACK UP. . . . . . . . . . . . . .2 STARTING & ENDING. . . . . . . . .3 MONITORS . . . . . . . . . . . . .3 CALCULATOR PROGRAM KEYING IN NUMBERS. . . . . . . . .4 CORRECTING NUMBERS . . . . . . . .5 REVERSE POLISH NOTATION. . . . . .5 REGISTERS. . . . . . . . . . . . .6 CALCULATIONS Single Register . . . . . . . .6 Dual Register . . . . . . . . .7 Chain Calculation . . . . . . .9 FUNCTIONS. . . . . . . . . . . . .11 General . . . . . . . . . . . .12 Logical . . . . . . . . . . . .14 Memory. . . . . . . . . . . . .16 Stack . . . . . . . . . . . . .17 MEMORY Store . . . . . . . . . . . . .18 Recall. . . . . . . . . . . . .19 Arithmetic. . . . . . . . . . .19 Memory Display. . . . . . . . .20 Clear Memory. . . . . . . . . .21 STACK OPERATIONS Push. . . . . . . . . . . . . .21 Pop . . . . . . . . . . . . . .23 Clear Stack . . . . . . . . . .24 STACK MANIPULATION Rotate Stack. . . . . . . . . .25 Swap X & Y. . . . . . . . . . .26 CONSTANT CALCULATIONS. . . . . . .26 RANGES . . . . . . . . . . . . . .27 ERRORS MESSAGES. . . . . . . . . .28 CONVERSION PROGRAM NUMBER FORMAT & RANGE. . . . . . .29 CONVERTING . . . . . . . . . . . .30 2'S COMPLEMENT . . . . . . . . . .31 ERRORS . . . . . . . . . . . . . .32 PROMPTS. . . . . . . . . . . . . .32 Programmer's Calculator Page 1 STARTING UP INTRODUCTION Programmer's Calculator is divided into two programs, Calculator and Conversion. After the initial screen the first screen displayed is the calculator program. To access the Conversion program screen use the function key (F10). This key is used to toggle between the two programs. When switching between programs, the program you leave is frozen at the point you pressed (F10). This allows you to return to the program where you left off. The Calculator Program is a powerful Reverse Polish Notation calculator. The calculator displays on screen the four stack registers, six memory registers and a display register; there by making it unnecessary to write down the contents of the registers when making complex calcula- tions. In addition to the general funct- ions found on most calculators the Pro- grammer's Calculator has six logical functions (and, or, not, etc.). Numbers used in the general calculations may be up to 16 digits in accuracy. The Conversion Program provides a fast and efficient way to convert numbers between decimal, hexadecimal, binary, and octal. Numbers up to 20 bits binary may be converted and the two's complement may be calculated on numbers up to 15 bits in length. Programmer's Calculator Page 2 SYSTEM REQUIREMENTS Programmer's Calculator requires the following minimum requirements to operate. IBM Personal Computer 128K ram memory 1 disk drive BACK UP Before working with the Programmer's Calculator copy the program onto another disk and save the Master Disk in a safe place. You may copy Programmer's Calcula- tor onto a hard disk for rapid access, or on any disk you may need for your personal work. This program is copyrighted and selling of the program for personal gain is strictly prohibited. Because this program is marked under the concept of Freeware you may copy the program for distribut- ion. If you find this program to be of use to you the author recommends a $15.00 donation. Further versions may become available if there is sufficient response. If you put the program on a fresh disk then format the new disk using the format instructions in the IBM DOS manual. Copy Procedure Single Drive: a. Insert Master Disk in Drive A b. Type: copy PC.EXE b: c. Read prompt, remove Master Disk and insert Backup disk and press any key. Programmer's Calculator Page 3 Copy Procedure Dual Drive: a. Insert Master Disk in Drive A and insert Backup Disk in Drive B. b. Type: copy PC.EXE b: With the program safely copied store Master Disk in a safe place for protection in case your backup is damaged. STARTING & ENDING To run the program place a disk with the program on it and type PC. After a few seconds the opening screen will be displayed. Once the program is initialize the calculator screen will automatically replace the initial screen. If for some reason the program does not start, get the master disk out. The Master Disk comes with PC.EXE (Programmers Calculator), GC.EXE (General Calculator), PCMANUAL.TXT (program manual), and MANUAL.BAT (used to generate a copy of the manual). To end the program and return to DOS press the ESC key. MONITORS Programmer's Calculator will run on either the color/graphics card or the monochrome card. During the initialization process the program checks for the type of card installed and runs accordingly. If both monitors are installed the program defaults to the Color/Graphics Card. Programmer's Calculator Page 4 CALCULATOR PROGRAM KEYING IN NUMBERS All numbers entered into the calculator program appear in the double boxed display under the stack. Positive Numbers: Key in the number as it is written but do not include the commas. Numbers will aligned on the left hand side of the display, and may be up to 16 digits long including the decimal place. Example: Enter the Number 1,345,776.732 Keystroke Display 1345776.732 1,345,776.732 Negative Numbers: To enter a negative number, key in the number as above then press F4. A minus sign will appear in front of the number. Example: Enter the number -123.4 Keystroke Display 123.4 (F4) -123.4 Press F4 again and the number will become positive. The key (F4) acts as a toggle between positive and negative numbers. Before continuing to the next section, press the tab key (|<-) and the back space key (<--). These keys will clear the stack and display registers respectively. Programmer's Calculator Page 5 CORRECTING NUMBERS Single digit: If, during the process of entering a long number, you entered a digit incorrectly, you may correct the entry. Press (^) and the (Del) key simul- taneously and the last digit entered will be deleted. By repeating the keystroke and you may delete as many digits as needed. Example: If you entered 12,456.3 but meant to enter 1,245.63 Keystroke Display 12456.3 12,456.3 (^)(Del) 12,456. (^)(Del) 12,456 (^)(Del) 1,245 .63 1,245.63 Whole numbers: To delete the entire number press the Backspace key (<--). This clears the number in the display and pops the stack (see Stack Operations). To enter a new number just enter the number as you would normally. Example: You typed 239 but meant to type .239. Keystroke Display Stack 1 239 239 0. (<) 0. 0. .239 .239 0. REVERSE POLISH NOTATION The Programmers Calculator uses Reverse Polish Notation (RPN) logic in the calcu- Programmer's Calculator Page 6 lation of numbers. RPN is a fast and efficient method for long calculations, but may take some getting used to if you are new to the logic. If you have never worked with a RPN calculator, read this manual carefully to take full advantage of the power of the calculator. If you have used used RPN logic on other calcu- lators, this system will be very familiar to you. REGISTERS In order for a calculator or computer to perform calculations it must store the numbers it is working on. In general this space is called memory. The Programmer's Calculator divides the memory into registers. Each register will hold one 16 digit number. Programmer's Calculator has 11 registers displayed on the screen (6 memory, 4 stack, 1 display). All primary operations (add, subtract, square root, etc) involve the display register (the double boxed register under the stack) by itself, or the display register with either one of the memory registers or the stack 1 register [S1]. Functions that use the display register alone are referred to as single register functions. Functions the require the use of two registers are referred to as dual register functions. CALCULATIONS Single Register Functions The single register function uses the value in the display register as input for the calculation. The result is placed Programmer's Calculator Page 7 back in the display register, and no other registers are effected. An example of a single register function is the change sign function described in entering negat- ive numbers. Other single register funct- ions include square root, square, absolute value, logical not, etc. Single register functions are performed by: a. Entering the number b. Pressing the appropriate function key Example: Take the square root of 25 Keystroke Display 25 25 (F3) 5 Dual Register Functions Dual register function make use of two registers. One register is always the display register the other register is either the stack 1 register or one of the memory registers. Most of the operations made on the calculator (add, subtract) require two numbers. RPN logic calculat- ors use the stack as a temporary storage for one of the numbers. In RPN logic the two numbers are entered into the calculator then the operation is performed. This will seem awkward a first, but a little experience will illustrate the power of the logic. In order for the calculator to different- ate between the two numbers the enter key Programmer's Calculator Page 8 (<-') is pressed after the first number is entered. In effect the (<-') is used to push numbers on the stack where they are held in temporary storage until needed. Example: To add 22 + 15 a. type 22 first number b. press (<-') 22 is pushed on to the stack c. type 15 second number d. press (+) perform function Keystroke Display Stack 1 22 22 0. (<-') 22 22 15 15 22 (+) 27 0. As you can see by the example the first number was temporarily stored in stack until it was needed. The use of the stack for the storage of numbers or partial results of calculations is a powerful feature of RPN logic. Before continuing to the next section, press the tab key (|<-) and the back space key (<--). These keys will clear the stack and display registers respectively. In the previous example you will note that we had the value of 22 in the display register and in stack 1 after the second operation. We can make use of the 22 in the display register instead of overwrit- ing it with 15. By pressing the (+) key instead of entering 15 the number is doubled to 44. Programmer's Calculator Page 9 Example: Double the number 22 Keystroke Display Stack 1 22 22 0. (<-') 22 22 (+) 44 0. Try out the following calculations before going on to chain calculations. 1. 22 x 25 = 550 2. 20 - 15 = 5 3. 20 / 4 = 5 4. 5^3 = 125 5. 5^1/3 = 1.7099759... Chain Calculations Long operations using multiple numbers are performed easily using RPN logic. Long calculations are broken down into smaller two register operations and the inter mediate result of each operation is stored in the stack where it cam be combined with the results of other operations. PC calculator allows up to four intermediate results to be stored in the stack. The result of an operation on the two numbers is in the display register. This result may then be used in a single register function or pushed on the stack and later combined with other numbers. To perform a calculation with the results of the first calculation and another number, simply enter the next number and perform the calculation. When you enter the next number the result of the first calculation is automatically pushed form the display register into the stack 1 register. You Programmer's Calculator Page 10 now have the result of the first calcu- lation in stack 1 register and the new number in the display register. To complete the calculation press the desired function key. Example: Calculate the equation (22 + 5) x 10 With the calculation of any equation, always perform the operation in the inner most level of parenthesis first, Then work you way to the outer levels of parentheses. a. type 22 fist number b. press (<-') push 22 in stack c. type 5 second number d. press (+) perform addition e. type 10 enter next number result of first operation (27) automatically pushed on the stack f. press (*) perform multiplication, result in the display register Keystroke Display Stack 1 22 22 0. (<-') 22 22 5 5 22 (+) 27 0. 10 10 27 (x) 270 0. Programmer's Calculator Page 11 Try the following operations before continuing. If you do not get the correct results review the section again. (23 + 8) x 15 = 465 ((4 x 16).5) x 10 = 320 (1,234.43 / 55) x 2 = 44.8883636... More complicated problems are solved by temporarily storing the intermediate results of each operation in the stack until needed. Example: To solve (22 + 15) x (32 / 2) The results of the operation in each set of parenthesis is calculated. The results of the two intermediate calculations serve as input values for the final calculation. Keystroke Display S1 S2 22 22 0. 0. (<-') 22 22 0. 15 15 22 0. (+) 37 0. 0. 32 32 37 0. (<-') 32 32 37 2 2 32 37 (/) 16 37 0. (*) 592 0. 0. FUNCTIONS In this section each function available on the PC calculator will be discussed. Programmer's Calculator Page 12 The functions available on the calcu- lator are displayed in the lower left hand corner of the screen on the template. Since all of the functions can not be displayed at once the (F9) key is used to toggle between the two template. The keystroke used to invoke the function is illustrated in the template in an abbreviated form. For example the keystroke (Ctrl)-(F3) is representable by CF3. All key-strokes listed in this section separated by a dash [(Ctrl)-(F3)] should be pressed simultaneously. The symbol is the representation of the function as displayed on the template. General Functions Function Keystroke Symbol Add (+) + Subtract (-) - Multiply (*) * Divide (/) / Two register function Used to manipulate numbers in the display and the stack 1 register with the results in the display register. May also be used to manipulate display and a memory register with the results in the memory register. Programmer's Calculator Page 13 Function Keystroke Symbol Square (F3) x^2 Single register function Used to take the square of the number in the display register. Function Keystroke Symbol Square root (Alt)-(F3) x^1/2 Single register function Used to take the square root of the number in the display register. Function Keystroke Symbol X to n (^)-(F3) Xn Dual register function Used to raise X to the Power n. X is the number in stack 1 register and n is the number in the display register. Function Keystroke Symbol X to 1/n (Ctrl)-(F3) X^1/n Dual register function Used to raise X to the power of 1/n. X is the number in the stack register and n is the number in the display register. Programmer's Calculator Page 14 Function Keystroke Symbol Absolute value (Alt)-(F4) |x| Single Register Function Used to take the absolute value of the number in the display register. Function Keystroke Symbol Inverse (^)-(F4) 1/x Single register function Used to take the inverse of the number in the display register. Function Keystroke Symbol Change sign F4 + Single register function Used to change the sign of the display register. Logical Functions Function Keystroke Symbol And F5 AND Or F6 OR Xor F7 XOR Imp (^)-(F5) IMP Equ (^)-(F6) EQU Dual register function Programmer's Calculator Page 15 The bits in the numbers in the display and stack 1 register are compared and the result placed in the display register. The bits are compared using the following tables. AND X Y Result 1 1 1 1 0 0 0 1 0 0 0 0 OR X Y Result 1 1 1 1 0 1 0 1 1 0 0 0 XOR X Y Result 1 1 0 1 0 1 0 1 1 0 0 0 EQV X Y Result 1 1 1 1 0 0 0 1 0 0 0 1 IMP X Y Result 1 1 1 1 0 0 0 1 1 0 0 1 Programmer's Calculator Page 16 Function Keystroke Symbol Not (F8) NOT Single register function The bits of the number in the display register are reversed according to the table. NOT X Result 0 1 1 0 Memory Functions Function Keystroke Symbol Store F1 STO Dual Register Function Used to copy the contents of the display register into one of the memory registers. Requires a number (indicating the memory location) to be entered after pressing the F1 key. By entering one of the four arithmetic functions before entering the storage location, the contents of the memory location is add, subtracted, multiplied, or divided with the contents of the display register. Function Keystroke Symbol Recall F2 RCL Dual register function Programmer's Calculator Page 17 Used to copy the contents of a memory register into the display register. Requires a number (indicating the memory location) to be entered after the F2 key is pressed. Function Keystroke Symbol Clear Memory (^)-(|<-) Clear memory Multiple register function Used to clear all of the memory registers in on operation. It uses the shift tab key. Stack Functions Function Keystroke Symbol Clear stack (->|) Clear stack Multiple register function The clear stack function allows you to clear the contents of the stack between calculations. It uses the tab key. Function Keystroke Symbol Rotate Stack (^)-(F2) R^ Multiple register function The rotate stack function allows you to rotate the contents of the stack, Each time the (^)-(F2) is pressed, the stack will rotate one number. Programmer's Calculator Page 18 Function Keystroke Symbol Swap X & Y (Alt)-(F2) X <-> Y Dual register Function The swap function exchanges the contents of the display register with the contents of the stack 1 register. MEMORY The Programmers Calculator has six memory registers (listed M1-M6) displayed across the top of the screen. This elimi- nates the need to write down the contents of the memory registers when performing calculations. Store Numbers in the display register may easily be copied into a memory register by first pressing (F1) and second entering the number of the memory register to receive the number. The process of copying a number into a memory register does not affect the contents of the dis- play register; however, the previous contents of the memory register are over- written. Example: Place 1345.6 into memory register (M2). Keystroke Display M2 1345.6 1,345.6 0. (F1) 2 1,345.6 1,345.6 Programmer's Calculator Page 19 Recall To retrieve numbers from a memory register, press (F2) followed by the number of the register that contains the number to be copied. The contents of the memory register are unaffected by the copy process. The contents of the display register are either overwritten or pushed into the stack depending upon the previous operation (see stack operations for the effect of an operation on the stack). Example: Retrieve the contents of M2. Keystroke Display M2 0. 1,345.6 (F2) 2 1,345.6 1,345.6 Arithmetic Contents of a memory register are affected when a number is stored or when a memory register is performed. The functions that may be used with memory registers are add, subtract, multiply, and divide. The results of calculations using a memory register and the display register are stored in the memory register. Example: Add the number 22 to the contents of M2. a. enter 22 number to be added b. press (F1) set up the store c. press (+) press key of operation to be performed Programmer's Calculator Page 20 d. press 2 number of the memory register the number is added to Keystroke Display M2 22 22 1,345.6 (F1) (+) 2 22 1,367.6 Example: Subtract the number 67.6 from the contents of M2. Keystroke Display M2 67.6 67.6 1,367.6 (F1) (-) 2 67.6 1,300 Try out following examples. a. Store 500 into M1 and divide 20 into the register, answer is 25. b. Multiply the contents of M1 by 25, answer is 625 To cancel a memory function before completion, press the enter key. You may then use the number in the display register as a function value or overwrite the number with a new number. Memory Display The contents of the memory register are displayed in single precision while the contents of the display register are displayed in double precision. This will not affect what you see in the memory register unless the numbers you are work- ing with are longer than 7 digits. Any Programmer's Calculator Page 21 number longer than seven digits in memory will be displayed in scientific notation. Internally the computer stores the numbers in double precision so operations on the numbers are unaffected. When large numbers are retrieved from the memory they will be displayed in the format in which they were stored. Clear Memory The contents of memory may be cleared one register at a time or all of the registers at once. To clear one register store 0 into the register with the store function. To clear all of the registers at once press the shift and tab key simultan- eously. This will clear out all of the memory registers. STACK OPERATIONS The stack is the heart of the RPN logic calculator. By learning to use the stack efficiently you will be able to perform complex calculations easily and quickly. Push The stack is composed of four registers residing on top of each other labeled one to four. As you learned earlier numbers are pushed into the stack with the enter key (<-'). Continued pressing of the (<-') will continue to push the number deeper into the stack. This operation is Programmer's Calculator Page 22 called pushing the stack. As you will see the first number pushed on to the stack will be the last number popped off the stack. The enter key is used to push the number in the display register onto the stack. When the number in the display register is the results of a numeric operation, the stack is automatically pushed when the next number is entered. When the stack is pushed the number in stack 4 register is discarded the number in stack 3 register takes its place. The numbers in each register are pushed up in the next highest register and finally the number in the display register is moved up into the stack 1 register. Example: Clear out the stack and try out the following keystrokes. 1 (<-') stack 4 0. stack 3 0. stack 2 0. stack 1 1 display 1 2 (<-') stack 4 0. stack 3 0. stack 2 1 stack 1 2 display 2 3 (<-') stack 4 0. stack 3 1 stack 2 2 stack 1 3 display 3 Programmer's Calculator Page 23 4 (<-') stack 4 1 stack 3 2 stack 2 3 stack 1 4 display 4 5 stack 4 1 stack 3 2 stack 2 3 stack 1 4 display 5 In the example we did not press (<-') after entering 5. Therefore the value of 5 was not pushed into the stack. If we press (<-') now the stack will be pushed and the number in stack 4 will disappear. (<-') stack 4 2 stack 3 3 stack 2 4 stack 1 5 display 5 Pop When the stack is popped the operation is the reverse of the push. The contents of stack 1 register is moved into display register and the contents of stack 2 register is moved into stack 1 register and so forth. are popped from the stack by popping the stack. Numbers are retrieved from the stack by popping the stack. All dual register functions that use the stack as the second register, automatically pop the stack. During the calculation the stack is popped and result left in the display register. Programmer's Calculator Page 24 In fact the display register is an extension of the stack with one except- ion. When the stack is pushed the display register always retains the number that was pushed into the stack. You then have the option of using the number in the display register again or entering a new number. If you do not enter a new number then when you perform a function the number in the display register becomes one of the input values of the function. If you enter a new number the display is cleared to make room for the new number. Try the following examples. Example: Double the value of 45. Keystroke Display Stack 1 45 45 0. (<-') 45 45 (+) 90 0. Example: Multiply 45 by 2 Keystroke Display Stack 1 45 45 0. (<-') 45 45 2 2 45 (*) 90 0. Clear Stack To clear the contents of the stack press the tab key. All of the stack registers will be set to zero, but the contents of the display register will be unaffected. Programmer's Calculator Page 25 STACK MANIPULATION Programmer's Calculator provides two functions to manipulate numbers within the stack. These functions allow you to rearrange the contents of the stack for calculation. Rotate Stack The rotate stack function allows you to rotate the stack and the contents of the display register. The contents of the display resisters are moved into stack 4 register and the stack is popped. Example: Enter the following sequence 1 (<-') 2 (<-') 3 (<-') 4 (<-') 5 Keystroke Register Contents stack 4 1 stack 3 2 stack 2 3 stack 1 4 display 5 (^)-(F2) stack 4 5 stack 3 1 stack 2 2 stack 1 3 display 4 Before continuing to the next section, press the tab key (|<-) and the back space key (<--). These keys will clear the stack and display registers respectively. Programmer's Calculator Page 26 Swap X & Y The Swap X & Y function exchanges the contents of the display register and the stack 1 register. Press (Alt)-F2) and the two number are exchanged. Example: Enter the two numbers and swap the registers. Keystroke Display Stack 1 34 34 0. (<-') 34 34 15 15 34 (Alt)-(F2) 34 15 CONSTANT CALCULATIONS Whenever a number is in the stack 4 register and the stack is popped, the contents of stack 4 is duplicated in stack 3 and stack 4 remains unchanged. This handy feature is useful in calculations that require constant value input. Example: Enter the following 4 (<-') 2 (<-') 3 (<-') 4 (<-'). Keystroke Registers Contents stack 4 4 stack 3 2 stack 2 3 stack 1 4 display 4 (+) stack 4 4 stack 3 4 stack 2 2 stack 1 3 display 8 Programmer's Calculator Page 27 (+) stack 4 4 stack 3 4 stack 2 4 stack 1 2 display 11 (+) stack 4 4 stack 3 4 stack 2 4 stack 1 4 display 13 (*) stack 4 4 stack 3 4 stack 2 4 stack 1 4 display 52 (*) stack 4 4 stack 3 4 stack 2 4 stack 1 4 display 208 RANGES Input values Numbers entered into Pro- grammers Calculator may be up to 16 digits in length. The program does not support the input of numbers in scientific notation. Calculated Values Numbers generated by calculation may range from 2.9E-39 to 1.7E-38. Any number generated outside of that range will cause an "Out of Range" error message to be displayed. Logical Values Operations using the logical functions will work on integer Programmer's Calculator Page 28 numbers from -32,768 to 32,767. Attempting to use invalid numbers will cause an error message to be displayed. ERROR MESSAGES The calculator program will display error messages for illegal operations. These messages are displayed just above the display register. The error message will be display until the next keystroke. The number in the display register may be used with any function. The number will be overwritten if you attempt to enter a new number without first pushing the number on the stack. If you continue to get error prompts check with the manual for correct proced- ures. Beep: The computer will beep if you attempt to enter an incorrect keystroke. Check the manual to determine the correct procedure. Out of Range: This prompt will be display- ed if you attempt to preform an operation with a number that is out of the range of the program. Division By Zero: This prompt is displayed if you attempt to divide zero into any number. Illegal Function: Any function or combin- ation of keystrokes that is unknown to the program will cause the prompt to be displayed. Programmer's Calculator Page 29 CONVERSION PROGRAM NUMBER FORMATS & RANGES The format of the number entered in the Conversion Program varies depending upon the type of number being entered (hexadec- imal, decimal, etc.). A beep will be sounded if you attempt an invalid character. Numbers that are out of allowable ranges will cause a appropriate error message displayed at the bottom of the screen. Decimal: Any digits between 0 and 9 inclu- sive are valid for entering decimal numbers. Negative signs may be entered when entering negative numbers. The sign is entered first followed by the number. The range of valid decimal numbers is -32,768 to 1,048,575. Hexadecimal: Any digits between 0 and 9 inclusive and characters between A and F inclusive are valid for entering hexadec- imal numbers. Letters may be upper or lower case. The range of valid hexadecimal numbers is 00000 to FFFFF. Binary: Only 0 and 1 are used to form valid binary numbers. Binary numbers must be entered in groups of four. The range of valid binary numbers is 0000 to 1111 1111 1111 1111 1111. Programmer's Calculator Page 30 Octal: Any digits between 0 and 7 inclusive are valid for entering octal numbers. The range of valid octal numbers is 0 to 3,777,777 CONVERTING Converting number is a simple task. At the top of the screen is a menu of the conversion options. 1 Decimal 4 Octal 2 Hexadecimal 5 2's Complement 3 Binary F10 Calculator Enter one of the selection between 1 and 5. The "Enter Choice" prompt in the middle of the screen will be replaced by a prompt corresponding to the selection. Enter the number to be converted then press the enter key (<-'). The conversion will be displayed at the bottom of the screen next to the appropriate type. The prompt will be replaced with the "Enter Choice" prompt and you are ready to convert the next number. Numbers entered in correctly may be corrected by entering the backspace key. Press the key once and the last character entered is deleted. Programmer's Calculator Page 31 If you enter a choice and decide you do not want to enter a number of that type then simply press (<-') and the current prompt will be replaced by the "Enter Choice" prompt. Example: Convert decimal 798 a. press 1 b. read prompt c. type 798 d. press (<-') Results: Decimal 798 Binary 0011 0001 1110 Hexadecimal 31E Octal 1,436 2'S COMPLEMENT To calculate the 2's complement press 5 at the "Enter Choice" prompt. The numbers at the bottom of the screen will be recal- culated and the 2's complement of the number displayed. Press 5 again and the original numbers will appear again. The 5 will toggle between regular notation and 2's complement. 2's complement will only work on numbers in the range of -32,768 to 32,767. Attempting to calculate the complement of a number outside this range will result in an error message. Programmer's Calculator Page 32 ERRORS The program responds to four types of errors. For invalid keystrokes the program will beep. For the rest of the errors the program will respond with visual responses at the bottom of the screen. The error message will remain resident on the screen until the next keystroke. Too Few Digits (Enter in groups of four): This prompt will be displayed if the you attempt to enter a binary number with an invalid number of digits. Out of 2's Complement Range -32768 to 32767: This message is displayed if you attempt perform a 2's complement that is out of range. Out of Range: This message is displayed for any number entered that is out of range. PROMPTS The following prompts are displayed according to the menu item selected. Decimal: Enter Decimal Number (-32,768 to 1,048,575) Hexadecimal: Enter Hexadecimal Number (0 to FFFFF) Binary: Enter Binary Number (20 Digits Max) Octal: Enter Octal Number (0 to 3,777,777)