ECE-3120
Spring 2008
LAB 3 –PROGRAM LOOPS
The purpose of this lab is to introduce you to basic programming on the 68HCS12 using
program loops, branching, and arithmetic instructions. You will NEED to study about
the arithmetic and branching instructions in Huang chapter 2 before attempting this
program.
PRE-LAB:
Prepare pseudocode and the first draft of the program and calculate the expected results
by hand. This must be completed before coming to the lab and shown to the lab instructor
at the start of the lab session. Note: The Pre-Lab must be typed into a proper *.ASM
source file, following our standard Program Format requirements.
Approved: Lab TA _____________________ Date ____________
PROGRAMMING ASSIGNMENT:
Write a fully-commented program for the HC12 board, following our standard Program
Format requirements (http://iweb.tntech.edu/rhaggard/3120s08/Program_Format.htm),
including appropriate directives and labels for memory operands and constants, called
Loop.asm. It must use a single program loop for most of the work. The program should
do the following:
• Be able to process any array containing 1 to 255 signed data bytes as follows.
Each byte can thus have a value between -128 and +127. This means that the
program should be able to handle any size array in this range, with any set of
values, by changing ONLY the directives that create the array values and
array size, without modifying any instructions.
• Calculate the sum of all the positive numbers in the array.
• Calculate the sum of all the negative numbers in the array.
• Count the number of zeros in the array.
• Calculate the total sum of all numbers in the array.
• The code must start execution at $1000.
The program directives should initialize the following signed decimal data byte array
in the data space (starting at $1200):
100, 127, -127, 22, 0, -8, -1, 0, 1, 120, 77, -45, 0, -99, in this order.
2/19/08 Page 1 of 3 Lab 3
