4.7 Mobile Computers

jiggerbarnacleMobile - Wireless

Nov 24, 2013 (3 years and 7 months ago)

61 views

§
4.7 Mobile Computers

Douglas Wilhelm Harder,
M.Math
. LEL

Department of Electrical and Computer Engineering

University of Waterloo

Waterloo, Ontario, Canada


ece.uwaterloo.ca

dwharder@alumni.uwaterloo.ca


© 2012 by Douglas Wilhelm Harder. Some rights reserved.

Based in part on Gary Nutt,
Operating Systems
, 3
rd

ed.

Outline


This topic will look at mobile computing:


Restrictions


System
-
on
-
a
-
Chip technology


Power management

2

Restrictions


Restrictions on mobile computing devices:


Small battery
-
powered power supply


Thus, it must have low power consumption


Restrictions on RAM and internal storage


A small screen often serves as both input and output


Fewer peripherals

often removable



3

System
-
on
-
a
-
Chip (SOC) Technology


One solution has been to integrate peripherals onto the
same chip as the CPU:


Often with digital, analogue, and radio
-
frequency functions


Differs from microcontrollers in terms of

scale and intended purpose

User:Stannered

4

System
-
on
-
a
-
Chip (SOC) Technology


Often, SOC will contain dedicated hardware:


Hardware MP3 or MPEG coding or decoding



Dedicated hardware will significantly reduce both time
and energy requirements


When you consider all the operations and checks that are
performed with executing just one instruction, you’ll appreciate
this...


In 2007, one ECE 4
th
-
year design project group, H
-
Quad,
implemented a FLAC decoder in hardware

5

Power Management


Laptop computers have hard drives and displays as their
largest consumers of energy


Strategies for powering these components down are critical to
extending battery life on these devices


Screens will be dimmed over time and then turned off


Sleep mode turns off most components other than main memory


Hibernation copies main memory to a persistent storage medium
and turns off that power as well



Tablet computers often use solid
-
state drives

6

Power Management


PDAs and
Smartphones

have significantly reduced
displays but also power
-
management features built into
the CPU:


Dynamic frequency scaling

allows the processor to run at
different speeds

7

Summary


This topic looked at aspects
specific to mobile
computing:


Restrictions


System
-
on
-
a
-
Chip technology


Power management

8