Homework Assignment 4
Due Feb. 16, 2000

1. Find the values of the N, C, Z, and V bits of the CCR register after execution of each of the following instructions, given that [A] = 0x50 and the condition flags are N=0, C=1, Z=1, and V=0. (Assume these are the values before each instruction starts -- e.g., do not use the flag state resulting from the intstruction in part (a) as the initial state for part (b).)
   1. TSTA
   2. ADDA #$67
   3. LSLA
   4. CMPA #$60
   5. SUBA #$70
   6. RORA

2. The following is the output from a program assembled using the CA6812 assembler. In a few cases the assembler output has been replaced by blanks. Fill in the blanks to show what the assembler output really was.

      1                     ; Example program for Homework 4
      2                     
      3       00000800      prog:    equ     $0800
      4       ________      data:    equ     $0900
      5                     
      6                     
      7       00000004      LEN:    equ     $04
      8                     
      9                     
     10                     CODE:   section .text   
     11  0800                       org     prog
     12  0800 de01          start:  ldx     val2
     13  ____ cc3344                ldd     #$3344
     14  0805 52                    ____    
     15  0806 6b__                  stab    LEN,x
     16  0808 9603                  ldaa    val2+2
     17  080a 5a04                  staa    _____
     18  080c ______                inc     count
     19  080f 3f            last:   swi
     20                     
     21                     
     22                     DATA:   section .data    
     23  0000 0a            val1:   dc.b    10
     24  0001 c200          val2:   dc.w    $c200
     25  ____ f0                    dc.b    ____
     26  0004 00000000      table:  ds.b    LEN
     27  0008 __            count:  dc.b    -10
   
   
   
   Map of junk.h12 from link file hw04.lkf - Fri Feb 04 16:29:50 2000
   
   LEN     00000004  
   count   00000008  
   data    00000900  
   ____    0000080f  
   prog    00000800  
   start   ________  
   table   00000004  
   val1    00000000  
   val2    00000001  
   
   

3. Write a sequence of instructions which will make bits 3-0 of PORT B input and bits 7-4 of PORT B output. These instructions should be in assembly language.

   
   

4. Write the program for Lab 4. Make sure you use top-down design, and document your program with comments. This program should be in assembly language.