Transcript Computer Confluence 7/e Chapter 2 Performance

Computer Confluence 7/e
Chapter 2
Performance
The architecture and word size of the processor .2
Architecture : the design that determines how the 
individual components of the CPU are put together
on the chip.
Newer chips can manipulate more bits 
simultaneously than older chips can. more
efficient more faster.
The number of bits a CPU can process at one time 
is called the CPU’s word size
High-end workstations and servers use 64-bit processors 
Most PCs and Macintoshes use 32-bit processors 
Some embedded and special-purpose computers still use 
8- and 16-bit processors
Computer Confluence 7/e
Chapter 2
Performance (continued)
Techniques for speeding up a computer’s ability to manipulate 
and move bits:
Parallel processing (symmetric multiprocessing or 
multiprocessing ): using multiple processors to divide
jobs into pieces and work simultaneously on the pieces.
Many PC have specialized subsidiary processors. Ex : 
math, graphic display.
Used in servers, workstations.
© 2006 Prentice-Hall, Inc.
Computer Confluence 7/e
Chapter 2
Performance (continued
Techniques for speeding up a computer’s ability to 
manipulate and move bits:
server clusters : a grouping of servers to improve 
rendering speed in computer graphics and increase
reliability.
How the CPU works
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How the CPU works
1- In most cases the actual execution of an •
instruction is performed by the CPU’s arithmetic
logic unit (ALU). The ALU includes registers,
each usually 32 or 64 bits in size.
2- Program instructions are stored in primary •
storage (memory), which is usually on chips
outside the CPU. The CPU’s first task is to read
an instruction from memory. The bus unit
handles all communication between the CPU
and primary storage.
How the CPU works
3- The prefetch unit, or prefetcher, instructs the •
bus unit to read the instruction stored at a
particular memory address. This unit not only
fetches the next instruction to execute, but it also
fetches several subsequent instructions to
ensure that an instruction is always ready to be
executed.
4-The decode unit takes the instruction read by •
the prefetcher and translates it into a form
suitable for the CPU’s internal processing. It
does this by looking up the steps required to
complete an instruction in the control unit.
How the CPU works
5 - If an instruction requires that information be sent out •
from the CPU—for example, written into memory—then
the final phase of execution is writeback, in which the
bus unit writes the results of the instruction back into
memory or some other device.
6 - Microprocessor manufacturers use many techniques •
to eliminate bottlenecks and speed up processing. For
example, in the same way it prefetches the next likely
instructions to be read, the CPU prereads the next likely
data to be used into a cache in memory (called a Level 2
cache (L2 cache) or, for faster access, in the CPU itself
(a Level 1 cache).
Computer Confluence 7/e
Chapter 2
The Computer’s Memory
RAM (random access memory) 
Used to store program instructions and data temporarily 
Divided into locations with unique addresses. 
data can be stored in any RAM location 
Can quickly retrieve information 
Will not remain if power goes off (volatile) 
© 2006 Prentice-Hall, Inc.
memory
Computer Confluence 7/e
Chapter 2
The Computer’s Memory (continued)
ROM (read-only memory) 
Information is stored permanently on a chip 
(nonvolatile)
Contains startup instructions and other permanent 
data
CMOS (complementary metal oxide semiconductor)
Special low-energy kind of RAM 
Store small amounts of data for long periods of 
time on battery power. (date, time, calendar in a
PC)
Flash memory 
Can be written and erased rapidly and repeatedly 
and it is nonvolatile.
Used for phones, pagers, portable computers, 
handheld computers, PDAs
© 2006 Prentice-Hall, Inc.
Computer Confluence 7/e
Chapter 2
The Computer’s Memory (continued)
Memory access time is another factor that 
affects the computer’s overall speed and is
measured in nanoseconds (ns).
Memory access time: the amount of time it 
takes for a CPU to retrieve a unit of data
from memory.
Memory
1 - When you turn on the computer, the CPU
automatically begins executing instructions stored in
read-only memory (ROM). On most computer systems,
ROM also contains parts of the operating system. The
firmware programs in ROM are sometimes called the
BIOS (basic input/output system).
2 - The executing instructions help the system start up
and tell it how to load the operating system—copy it
from disk into memory.
3 - Once executing instructions for O.S. are loaded into
memory, the CPU is able to execute them.
Memory
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Computer Confluence 7/e
Chapter 2
Buses, Ports, and Peripherals
Information travels between components on the motherboard 
through groups of wires called system buses, or just buses
© 2006 Prentice-Hall, Inc.
Computer Confluence 7/e
Chapter 2
Buses, Ports, and Peripherals (continued)
Buses
Typically have 32 or 64 wires or data 
paths.
Connect to storage devices in bays- 
open areas in the system box for disk
drives and other devices.
Connect to expansion slots- you can 
insert expansion cards into these slots.
Connect to external buses and ports- 
sockets on the outside of computer
chassis.
© 2006 Prentice-Hall, Inc.
Standard Computer Ports
USB
mouse
keyboard
serial
Parallel
Expansion slots
an expansion board being inserted into an
expansion slot
Computer Confluence 7/e
Chapter 2
Buses, Ports, and Peripherals (continued)
PC Card :
• Used on laptops,
• Devices are the size of a credit card
• contain memory, peripheral, addition ports.
Slots and ports Make it easy to add external devices,
called peripherals to the computer system so the CPU can
communicate with the outside world and store information.
Computer Confluence 7/e
Chapter 2
Inventing the Future
New laser etching technology called 
extreme ultraviolet lithography
(EUVL) could reduce chip size and
increase performance radically
Superconductors that transmit 
electricity without heat could increase
computer speed a hundredfold
The optical computer transmits 
information in light waves rather than
electrical pulses
© 2006 Prentice-Hall, Inc.
The only thing that has
consistently grown faster than
hardware in the last 40 years is
human expectation.
—Bjarne Stroustrup, AT&T Bell
Labs, designer of the C++
programming language
Computer Confluence 7/e
Chapter 2
Lesson Summary
A computer manipulates patterns of 
bits—binary digits of information
The CPU follows software instructions, 
reduced to strings of bits, to perform the
calculations and logical manipulations
that transform input data into output
Not all CPUs are compatible with each 
other
© 2006 Prentice-Hall, Inc.
The great Information Age is really
an explosion of non-information;
it is an explosion of data. To deal
with the increasing onslaught of
data, it is imperative to distinguish
between the two; information is
that which leads to understanding.
—Richard Saul Wurman, in
Information Anxiety
Computer Confluence 7/e
Chapter 2
Lesson Summary (continued)
The CPU uses: 
RAM (random access memory) as a temporary storage area—a scratch 
pad—for instructions and data
ROM (read-only memory), which contains unchangeable information 
that serves as reference material for the CPU as it executes program
instructions
The CPU and main memory are housed in silicon chips on the 
motherboard
© 2006 Prentice-Hall, Inc.