ET0104 EMBEDDED COMPUTER SYSTEM (Version 4.5)

ET0104 Embedded Computer Systems

Tutorial 1 Introduction to Embedded Systems

1. For a computer system indicate which bus or buses are being described.

a) A unidirectional bus.
b) Carries signals used to synchronize data transfer operations.
c) The MPU uses this bus to select a specific memory location for data transfer.
d) During a WRITE operation, this bus carries data from the MPU.
e) The number of lines on this bus determines the maximum memory capacity.
f) The number of lines on this bus determines the memory word size.


1. Buses are: a) Address b) Control c) Address d) Data e) Address
f) Data.


2. (a) “An embedded system does not use Graphical User Interface. Therefore they should not
need to use powerful processors.” Explain if this statement is true.


No, is not true. Embedded systems may need a powerful processor not just for the GUI, but for
sophisticated control algorithms using Fuzzy logic, neural networks and statistical signal
processing. Also, process sound and video data.


(b) In what way does increased processor power in desktops benefit embedded systems?


Older desktop versions will be used for embedded systems. So as desktops increase in
peformance, so will embedded.


(c) How do the Intel line of microprocessors maintain compatibility and yet provide extra
functions?

Provide real mode for compatibility and protected mode for advanced features.

(d) What are some ways computers increase in performance.

Speed, data size, address size, architecture

3. Describe some differences in characteristics between desktop and embedded systems.


Differences between embedded and other computers (See section 1.4) Fixed use / small
size / limited resource / failure tolerance / real time / response time / reliability / simple
I/O / low power / low cost.


4. What is the name given to a routine that is executed in response to an interrupt? What is the
difference between it and a normal subroutine?


Differences - Subroutine ISR
Called by program External events activate
Memory location varies Fixed location


5. What are the advantages of using interrupts to handle data I/O instead of using polling
method?

Interrupts - a) processor not tied up / b) fast to respond

6. Describe how the vectored interrupt system works.

Vectored interrupt system - see sect 1.5.1

7. Compare and contrast the differences between using software loops and hardware for timing
functions.


Software loops                                     Hardware
Processor tied up                                dedicated h/w
multitasking causes                             timing variation timing is accurate
timing varies due to prefetch              can be finer resolution than sofware