EE 361 LAB 4
                         ADDRESSING AND ARITHMETIC

References:    EE361 Texts
Schedule: Week of 9/29 Pre-lab due, do the lab
          Week of 10/6 Memo report due, last time to
          demonstrate the working program

1.   Pre-Lab:  
     a.   Come to the lab with a short description of
          how you will test that the program you do for part 2 works.  Describe any Buffalo
          monitor commands you will use and show what data you expect to see in BUF3 and
          BUF4.  Write this as a short memo report to your lab instructor.

2.   Create the following program 

a.Locates the program at $C000 using:
          ORG  $C000
          (Write your program op codes etc here)
     The program is to:

b.Add the bytes in BUF1 with the corresponding bytes in BUF2 and store the result in BUF3.

c.Take the two's-complement of BUF3 and store the results in BUF4.

d.You are to set up 4 data storage buffers of 12 bytes each.  Use the ORG, FCB and RMB
assembler directives to initialize data in the buffers as shown.

          ORG    $C100
     BUF1  FCB     $FF,$FF,$01,$70,$70,$70,$7F,$80,$82,$FF,$00,$01

          ORG     $C110
     BUF2  FCB     $01,$02,$01,$0D,$0E,$0F,$01,$01,$01,$FE,$FE,$FE

          ORG     $C120
     BUF3  RMB     $0C

          ORG     $C130
     BUF4  RMB     12

3.   Extra credit.  After  you have completed the program required for 2, add the capability
     to print out the contents of the four buffers in hexadecimal.  Each of the four buffers
     should be printed like this, with a label (BUF1: etc) followed by the hex display of
     the 12 bytes in each buffer.

     BUF1: FF,FF,01,70,70,70,7F,80,FF,00,01
     BUF2: 01,02,01,0D,0E,0F,01,01,FE,FE,FE
     BUF3: ...(contents of BUF3)...
     BUF4: ...(contents of BUF4)...

4.   Memo to:  Snodgrass P. Student
     From:          The Boss
     Date:          September 29, 1997
     Reference:     Unsigned binary and two's-complement codes

          Now that you have been employed by Two Dot Engineering for a couple of weeks, you
     should know something about programming the M68HC11 and how it performs unsigned and
     signed arithmetic.  After all these years at TDE, I still do not understand how the it
     handles signed and unsigned numbers and what the condition code register bits mean when
     it does arithmetic.  How does it know if the number is signed or unsigned?  Please
     explain it to me in a report using the new memo report style.  I especially want to
     know what happens to the flags in the condition code register when you two's complement
     a data value of $80.  Maybe you could use some examples from the program you just
     wrote.

5.   Grading:  Pre-Lab 10 points, demo (2) 10 points, memo report 20 points, extra credit
     (4) 5 points