INTRODUCTION. NOTE Some symbols used in this manual CL = Click Left CR = Click Right DCL = Double Click Left = Enter. Page 1

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1 INTRODUCTION OBJECTIVE The purpose of this manual is to provide the student with practical experience in the writing of assembly language programs, and give them background and instructions on how to use a microcomputer, an operating system, an assembler, and a text editor. During the execution of these programs, errors are bound to appear which will require the student to debug their programs. COURSE REQUIREMENTS Laboratory Experiments should be performed according to the schedule in the Learning Objectives. Prior to coming to Lab and entering source code using the text editor, it is expected the student will have a) read the required material in the textbook. b) read the laboratory experiment. c) written the source code for the program on a worksheet. Before coming to the Lab and beginning the First Exercise, the student should have read the material on the BIOS and MS/DOS operating systems in Appendix B and C. The student should feel free to obtain guidance from other students or the instructor, but it is expected that the student will write all programs. Beginning with Laboratory Exercise 4, the student will electronically submit an.asm listing of the program. The student will store all files on a floppy disk, which may be left with the Learning Assistants when not in use. NOTE Some symbols used in this manual CL = Click Left CR = Click Right DCL = Double Click Left = Enter Page 1

2 OBJECTIVE At the conclusion of this exercise, the student will be able to invoke the editor, insert text, move the cursor, correct mistakes by deleting or exchanging characters, copy or move text, and exit the editor while saving the file. S/he will use EDIT to create an assembly language source code program, invoke the assembler and create an Intel OBJ file and a LST file, and use the Linker program to an executable MS DOS program. INTRODUCTION The text editor used in this course is a full screen text editor called. If you have an IBM PC or compatible computer at home or have access to a word processor such as Microsoft Word, you may use this software to write the source code problems for this course. However, make sure the files are saved as ASCII text files (sometimes called non document mode). Saving files in the document mode places formatting information in the saved file. This will cause errors if the file is assembled. PROCEDURE 1. Apply power to the computer. Open a DOS Window in the Windows GUI, or reboot to the MS-DOS mode. Insert your work disk in drive A:. Make the floppy disk the default drive by entering the command: A: Copy all files from the C:\ELEC242 drive to your work disk. If you are working from home, download and unzip the go.bat and Irvine.lib files file from week 1 on the elec242 web site. On campus, we will be using a high-level text editor called TextPad. You may download the program from or you may use EDIT at the MS/DOS prompt. The following describes the process for using TextPad. Open an Existing File Follow these steps to open a text file in TextPad: 1. From menu bar, click on File. 2. From the File menu, select Open. 3. When the Open dialog appears Look In: the 3 ½ Floppy 4. Double-click the filename of the file that you want to open text.txt The file should then open in TextPad. TextPad was designed primarily for ASCII text files (specifically, files with the.txt extension). However, we may configure the program can be used to open other kinds of files too for example, assembler files (*.asm files). Editing A File The screen will clear and text that makes up the file TEXT.TXT is displayed on the CRT. It should consist of six lines similar to the following: The name of this file is TEXT.TXT. When you type ussing an edior, you often make a mistoke that you will have to correct. Notepad will allow you to correct the the problem, get rid of the bad stuff, move stuff around, and make your life easy. This is the first line of the text. Page 2

3 a. Locate the four arrow keys, which are located in two separate groups. If you wish to use the arrow keys on the numeric keypad, make sure the NUM LOCK LED is off. b. Place the cursor on a line in the middle of the text. To move the cursor to the first character on the first line of text, press the ^Home (CTRL-Home). Now press ^End and observe the cursor moves to the last character on the last line. c. Place the cursor on a line in the middle of the text. Press the HOME key. The cursor will move to the left margin on the current line. Press the END key and the cursor will move to the last character on the current line. d. Press the following keys:,,, and observe cursor movement. As you can see, there are several mistakes in the text. The fourth word of the second line ussing, is misspelled. The sixth word of the second line, edior, is missing a t. There is also an extra space after the word edior that must be removed. Additional errors are obvious and will be corrected. In addition, other functions will be demonstrated during the process of correcting the file. Some key functions perform the following actions: KEY PRESSED FUNCTION PERFORMED DEL INS Backspace Delete character to the right of the cursor Toggle between overtype and insert at the current cursor position Delete character to the left of the cursor Editing In Textpad 1. Press CTRL HOME to move the cursor to the beginning of the document. Press the DOWN ARROW key once and the RIGHT ARROW key 16 times. The cursor should be between ss in ussing. Press the DEL key. Verify that one s is removed. 2. Press the RIGHT ARROW key 10 times. The cursor is now between io in the misspelled word edior. Press the t key. Verify that a t is inserted before the o and editor is now spelled correctly. 3. Press the RIGHT ARROW key 4 times. Press the Backspace once. Verify that the extra space between the comma and you is removed. 4. Press the DOWN ARROW key once and then the HOME key. Press the RIGHT ARROW key 11 times. With the cursor between the t and the o in mistoke, press the Del key one time. Now press the a key and verify that the word mistake is now correctly spelled. 5. DCL on the second the in the fourth line. Press the DEL key and verify that the highlighted text is deleted. Also delete any extra spaces. As you have seen, the cursor can be moved about quite readily, and the editor allows you to enter characters into the middle of a word or sentence, and will allow you to delete one or more characters from the middle of a word or sentence. We will now see how to replace text using the search and replace features. 6. Place the mouse cursor over SEARCH on the menu bar and CL. FIGURE 1-1 Page 3

4 7. Place the mouse on Replace and CL. 8. The Replace Dialog Box, similar to Figure 1 on the previous page opens. 9. CL in Find What: 10. Enter the word Notepad. 11. Press the Tab key or CL in Replace with: Enter the word Textpad. 12. Place the mouse cursor Replace All and CL. Observe that the word Notepad was changed to Textpad. 13. CL on Close. Now perform the suggested moves to copy and move selected portions of the text. 15. Save the modified file on your work disk. CL on File. CL on Save as. Enter the name LAB1.TXT Cutting and Pasting Text Cutting text removes the highlighted (selected) text from the file, and places it in the clipboard. Using the Copy option, you copy text to the clipboard without removing it from its current location. Paste inserts the Clipboard contents at the current cursor location. We will now Cut and Paste some text from the current text file. 1. Position your mouse pointer at the beginning of the last line of text. This is the line that states This is the first line of the text. 2. While holding down your left mouse button, drag the pointer to the right so that the entire line is highlighted. Release the left mouse button. 3. From the menu bar, click on Edit. From the Edit menu, select Cut. The selected text is now removed and stored in the Windows clipboard. You could also press CTRL X on the keyboard. We will now paste the copied text: 4. Press CTRL HOME 5. Press the Enter key one time. 6. Press the up arrow key one time 7. From the menu bar, click on Edit. From the Edit menu, select Paste. You could also press CTRL V on the keyboard. Cutting and Pasting Text 1. Press CTRL A and verify that all the text is selected. 2. Click on Edit 3. Click on Copy 4. Press CTRL END 5. Press the Enter key 10 times 6. Click on Edit. 7. Click on Paste. Inserting Blank Lines We will now double-space only the first section of text. 1. Press CRTL HOME 2. Press END 3. Press Page 4

5 4. Press the down arrow 5. Repeat steps 2 through 4 until only the top text has one blank line inserted between each line of text. 6. Save the file on your 3 ½ floppy. 7. Print the file by Click on File Click on Print 8. Make sure you are printing to the HP 4050 network printer CREATING AN ASSEMBLY LANGUAGE SOURCE CODE FILE This section of the laboratory exercise you will create an assembler source code using a text editor, save the file, and assemble your program. This will create an executable program, which you will run. 1. Run Textpad 2. Click on File Open 3. Select the desired drive. 4. Type in the name HELLO.ASM. 5. A message box opens and states the file doe not exist. Select Yes to create a blank file The complete source code for the program HELLO.ASM follows, and must be entered exactly as shown. However, none of the text is case sensitive so it may be entered in uppercase or lowercase. Using the keyboard, enter the code: TITLE HELLO.ASM written by (enter your name) Page 60, 80 ; Brookdale Community College ; ELEC 242 ; Define the executable program size.model SMALL ; We should always create a Stack.STACK 2000H ; The following is the DATA Segment which is were ; we place a program data and storage.data OurString DB 'Hello there!',0dh,0ah,0ah,'$' ; The following is the CODE Segment which is were ; we place the executable code for the program.code.startup ; We must inform the program of the location of the data segment MOV MOV DS, AX ; CLEAR THE SCREEN MOV AH, 6 MOV AL, 0 MOV CX, 0 MOV DX, 1950H MOV BH, 1EH INT 10H MOV AH, 2 MOV DX, 0715H Page 5

6 MOV BH, 0 INT 10H ; CLEAR SCREEN ENDS ; PRINT THE MESSAGE MOV DX, OFFSET OurString MOV AH, 9 INT 21h ; NORMAL PROGRAM TERMINATION MOV AX, 4C00h INT 21h.EXIT END Save and close the file. You must now assemble and load the file. We will be using the Microsoft Assembler which comes with the text. Keep copies of all your asm files on a floppy or the c:\elec242 directory your home computer. ML assembles and links in one command. It may be entered in uppercase or lowercase. Since we wish to generate a LST file, we must use the switch /Fl (the last letter is lowercase L). These three characters are case sensitive. I have created a batch file, which is on your work disk, that simplifies the process. Its name is go.bat and is either on your work floppy or the elec242 directory on your hard drive. At the system prompt, enter the command: go hello You will see some messages on the display. Open the file HELLO.LST. It should look similar to the following: Microsoft (R) Macro Assembler Version /28/00 08:23:17 HELLO.ASM by (enter your name) Page CODE.STARTUP TITLE HELLO.ASM by (enter your name) Page 60,80 ; Brookdale Community College ; ELEC 242 ; Define the executable program size.model SMALL ; We should always create a Stack.STACK 2000H C 6C 6F 20 OurString DB 'Hello there!',0dh,0ah,0ah,'$' D 0A 0A C C8 MOV AX, CS ; This example mixes data and code. ; To have separate code and data segments, place a ;.DATA before OurString and move the.code here. ; We do not usually mix data and code. ; For small programs like this, it doesn't matter. Page 6

7 0029 8E D8 MOV DS, AX ; CLEAR THE SCREEN 002B B4 06 MOV AH, 6 002D B0 00 MOV AL, 0 002F B MOV CX, BA 1950 MOV DX, 1950H 0035 B7 1E MOV BH, 1EH 0037 CD 10 INT 10H 0039 B4 02 MOV AH, 2 003B BA 0715 MOV DX, 0715H 003E B7 00 MOV BH, CD 10 INT 10H ; CLEAR SCREEN ENDS ; PRINT THE MESSAGE 0042 BA 0017 R MOV DX, OFFSET OurString 0045 B4 09 MOV AH, CD 21 INT 21h ; NORMAL PROGRAM TERMINATION 0049 B8 4C00 MOV AX, 4C00h 004C CD 21 INT 21h.EXIT END Microsoft (R) Macro Assembler Version /28/00 08:23:17 HELLO.ASM by (enter your name) Symbols 2-1 Segments and Groups: N a m e Size Length Align Combine Class DGROUP GROUP _DATA Bit 0000 Word Public 'DATA' STACK Bit 2000 Para Stack 'STACK' _TEXT Bit 0052 Word Public 'CODE' Microsoft (R) Macro Assembler Version /28/00 08:23:17 HELLO.ASM by (enter your name) Symbols 3-1 Symbols: N a m e Type Value Number Number Number Number L Near 0000 Text Text Text Text Text DGROUP OurString Byte 0017 _TEXT 0 Warnings 0 Errors Page 7

8 The last two lines are the most important. If you have an error, go back to HELLO.ASM, fix the syntax error, and repeat the process. The lst file makes syntax errors easy to find. The linker will not create an executable file if there are errors. Warnings usually do not cause problems. If there are no errors, close the editor. At the system prompt on drive A, enter the command: HELLO What do you see? The program will clear the screen and print the message Hello there. If everything is working, send LAB1.TXT and HELLO.ASM to your instructor as an attachment. Make sure the message Subject is ELEC 242 Page 8