CS 2650 - Computer Architecture

CS2650 Assembler Assignment #4
Due before class on April 15th

Display the course on one line, your name on the next and and the DOS Day, Date and Time (am/pm) next, with the three lines at the left edge of the display beginning on line 5.
 

Perform the following steps on a PC in DOS.  Be careful to follow the steps exactly so as not to completely erase the hard disk or<worse>!

Use NASM to create assembler code to display the information formatted as follows:

• a.  Clear the screen using INT 10H service 06H
• b. Use INT 10H, Function 02H to position the cursor on line 5 at left edge of the display.
• c. Use INT 21H, Function 09H to display the course.
• d. Use INT 10H, Function 02H to position the cursor at the left edge of the next line.
• e. Use INT 21H, Function 09H to display your name.
• f. Use INT 10H, Function 02H to position the cursor at the left edge of the next line.
• g.  Get and display the current day of the week (Monday, etc.). 
  Use INT21H function 2AH to get the numeric version of the day of week. 
  Create code to convert the numeric day of the week to a text value (0 converts to "Sunday"). 
  You may want to use the CMP and conditional jump instructions in this conversion.
• h.  Get and display the current DOS date  (Use INT21H function 2AH ) immediately following the day of week. 
  You will need to convert the numeric month to it's alphabetic equivalent ie. 01h would convert to 'January'. 
  The day and year will need to be converted to ASCII using the DIV and ADD instructions
• i.  Get and display the current DOS time in am/pm format (Use INT21H function 2CH to get the time).   
  You will need to convert 24-hour time to AM/PM.  You may want to use comparisons for this also.
  Use INT 10H, Function 02H to position the cursor on the next line under the time.
• j.  Make sure that you have an INT 20H as your last command.

After thoroughly testing your program, upload BOTH the files: CS2650P4.ASM and CS2650P4.COM using the web uploader.

Interrupt 10H  Function 02H Position Cursor Inputs: AH 02H BH Video Page (always 00h) DH Row DL Column Outputs: None

Interrupt 21H  Function 09H Display String at present cursor location Inputs: AH 09H DX Offset address of String to display (The string must be terminated with a dollar sign $) Outputs: None

   
 

HINT:

To convert the parts of the date and time for display, you can use the DIV instruction to get the digits separated.

The DIV instruction performs 8 and 16 bit unsigned division.  A single operand is supplied (register or memory), which is assumed to be the divisor.  If the divisor is 8 bits long, AX is the dividend, AL the quotient, and AH the remainder.  If the divisor is 16 bits, DX:AX is the dividend, AX the quotient, and DX the remainder.

Example 1:    8-bit division  (18 / 10 = 1 remainder 8)

MOV AX, 18
MOV BL, 10
DIV BL

08h would be in AH, 01h in AL (try it!)

Example 2:    16-bit division (1999/1000 = 1 remainder 999)

MOV DX, 0
MOV AX, 1999
MOV CX, 1000
DIV CX

AX would contain 0001h and DX would contain 03E7h (999 decimal)