Page 46 - Introduction to Microcontrollers Architecture, Programming, and Interfacing of The Motorola 68HC12

PROBLEMS 23

PROBLEMS

1. Is a Hewlett-Packard handheld calculator, model 21 (or any programmable calculator
that you may select), a (von Neumann) computer, and why?
2 . What do the following terms mean: memory, controller, data operator,
input/output?
3 . What are a microcomputer, a microprocessor, and a single-chip microcontroller?
4 . Describe the terms clock, data bus, address bus, and read/write line. Discuss the
operation of reading a word from memory using these terms.
5 . How many memory read cycles are needed for the following instructions, using the
CPU 12 reference manual? How many are fetch operations, and how many are recall
operations? How many memorize cycles are used?

(a)LDAA #19
(b)LDAB #18
(c)ADDA $3FB2
(d)ADDA 23 (Use 16-bit direct addressing)
(e) STAA 199 (Use 16-bit direct addressing)
6. While executing a particular program, (PC) = 2088, (A) = 7, and (B) = 213 before
the following sequence is executed:
LDAA #10 Location Contents
ADDA 2142 2139 8
STAA 2139 2140 7
2141 16
2142 251
2143 19
If the contents of memory locations 2139 through 2143 are as shown on the right before
the sequence is executed, what will be the contents of A, B, and PC after the sequence is
executed? (Location is the memory location, or address, and Contents is the memory
contents. All numbers given are in decimal.) What will the C bit be equal to after the
sequence is executed?
7 . Write a program to add two 3-byte numbers in the same manner as the last program
segment of this chapter.
8 . Select goals for good programs in the following applications, and give a reason for
the goals. The goals should be: static or dynamic efficiency or clarity.

(a) A 75,000-instruction program
(b) A program for guidance of a space satellite
(c) A controller for a drill press
(d) An automobile engine controller
(e) Programs for sale to a large number of users (like a Basic interpreter)