CSc 343 Spring 1998, Programming Assignment #1

CSc 343 Computer Organization and Programming
Spring Quarter 1998
Programming Assignment #1 (Due: 24 April 1998, Friday)

Assignment Objectives:

To become familiar with Turbo Assembler and Turbo Debugger.
To gain experience with several basic features of assembly laguage, including stack segment, data segment, and code segment; the DB, DW, .MODEL, .CODE, .DATA, .STACK and PROC directives; the MOV, ADD, SUB, DIV, SHL and INT instructions.
To write your first assembly language program.

Problem Description:

Write an assembler program that will compute the number of vowels, consonants and spaces in a sentence stored in a string which is internally defined in the data segment of your program as follows:

SENTENCE  DB 'I hope to finish this assignment in time so that I do '
          DB 'not get a late penalty for this assignment.'

You may assume that the sentence contains only vowels, consonants and spaces and always ends with a period. The period is not used in any of the counts. The sentence may be big enough that it may not fit in one line as shown in the example. Your program should work for any sentence that is defined in the data segment of your program. The output of the program should look like the following (centered on the screen):

    
    Name: Raj Sunderraman
    This program executed on 10/06/1997 at 15:10:32
    16 x Number of vowels      =  464 
    16 x Number of consonants  =  768
    16 x Number of spaces      =  304
    16 x Total sentence length = 1536

The first line of the output should contain your name. The second line of the output should contain the date and time of execution of the program in the format indicated. You would have to obtain the system date and time to accomplish this. The remaining lines of the output should appear exactly as shown (except for the answers, which would be different depending on the time you ran your program and the sentence you include in the data segment). The output of your program should match, in every detail, the format illustrated above. Points will be deducted for any variation. The program should wait for user to press any key before terminating.

Submission Instructions: Electronically submit count.asm and count.exe by the deadline and submit a hard copy printout of the program listing of count.asm.

Hints:

To assemble the program use the /l and /zi options and use the /v option while linking as follows:
```
tasm /zi /l sum
tlink /v sum
```
To determine the system time and date use the DOS interrupt 21H as follows:
```
    
    MOV   AH,2CH ; get system time
    INT   21H
```
After the interrupt, CH contains the hour (00 - 23), CL contains minutes (00 - 59) and DH contains seconds (00 - 59).
```
    
    MOV   AH,2AH ; get system date
    INT   21H
```
After the interrupt, DH contains the month (01 - 12), DL contains day (01 - 31) and CX contains year (1980 - 2099).
After getting the system date and time, you need to convert the various components from numeric to character form by extracting digits one by one, adding 30H to each (to convert to ASCII), and storing the resulting character in a buffer. To extract a digit from a number n, just divide n by 10; the remainder is n's rightmost digit.
To divide a word by a byte, use the DIV instruction. For example,
```
  DIV  TEN
```
would divide AX by 10 (assuming TEN has been declared as a byte containing 10). After the instruction has executed, AL will contain the quotient and AH will contain the remainder. Notice that the instruction does not mention a register, since division is always done in the AX register. Warning: Instructions such as
```
   DIV  10
```
are rejected by the assembler.
To multiply a number by 16, you should use the SHIFT LEFT instruction as follows:
```
  MOV   CL,04H
  SHL   AX,CL
```
The contents of AX register are multiplied by 16.

To print the information on the screen, use the DOS interrupt 21H as follows:

   MSG   DB  'Hello!','$'  ; message string to be displayed
                        ; notice dollar symbol at end.
   ...
   ...
   MOV   AH,09H  ; request display
   LEA   DX,MSG  ; load address of message
   INT   21H     ; DOS interrupt

To clear the screen, use BIOS interrupt 10H as follows:

   
   MOV   AX,0600H ; AH 06 (scroll), AL 00 (full screen)
   MOV   BH,30    ; Attribute: color setting 
   MOV   CX,0000  ; upper left row:column
   MOV   DX,184FH ; lower right row=24,column=79
   INT   10H      ; interrupt call to BIOS

To set the cursor at a particular location on screen use BIOS interrupt 10H as follows:

   
   MOV  DL,10   ; column 10
   MOV  DH,5    ; row 5
   MOV  BH,0    ; page 0
   MOV  AH,02H  ; request set cursor
   INT  10H     ; interrupt call to BIOS

To wait for user to press any key before terminating use DOS interrupt 16H as follows:
```
   
   MOV   AH,10H
   INT   16H
```

Raj Sunderraman
Mon Apr 13, 1998