EECE 259 - Lab 5 - Using The Assembler and Debug Monitor.pdf

4 digits of your student number are “1257”, then the resulting 16 bit BCD number
should be 0001 0010 0101 0111. You should investigate the 68000 instruction set for
arithmetic shift left operations. Store the resulting 16 bit BCD number as a word in
memory (e.g. where there is some static memory such as at address $00010000).
Question: How many bytes of data will be stored and what is the address of each byte
and hence what is the address of the next free byte in memory.
Now read the 2 nd 4 digits of your student number and convert them into a 2 nd 16 bit
(4 digit BCD number) as above and store it somewhere else in memory (do not
overwrite the first data stored at $00010000).
Now, using Switch SW10, add or subtract the 2 nd four digits of your student number,
from the 1 st four digits and display the result as a 4 digit number on the HEX display.
That is, the program should run indefinitely, reading SW10 and performing addition
or subtraction based on SW10 position (up or down). Investigate the ABCD and
SBCD instructions in the 68000 instruction set for adding and subtracting in BCD.
Store the result in memory. Ignore negative results
When SW11 is moved into the up position, the program should stop and return to the
debug monitor using a Trap #15 instruction. Use the debugger to single step and
debug the program.