Transcript uploads/6/3/1/7/63175405/processing_data_chapter_4x

Processing data: Introduction to Processors
 CHAPTER 4
 Factors affecting Processing speed
1.
width of Registers: Register is a type of high speed
memory unit built onto the CPU used for calculations.
A 32 bit processor indicate the width of the register or
the word length that can be handled by the processor.
Register does arithmetic, logical and moving
operations. E.G. Register A hold content of 7 and B
holds content of 3: operation: compare Whether A>B. if
A>B true then divide A by B. so register C calculates
A/B=7/3=2.33. the result is stored in register D. the
moved to RAM. If not saved the hard disk the data is
lost RAM as RAM is volatile.
Factors affecting Processing speed
2. No of registers: having many registers facilitate
greater speed. e.g. PowerMac G5 has 80 register vs.
Pentium 4 has 16 registers.
3. RAM size: having a larger RAM/ memory
increases processing power. Upgrading a RAM is one
of the cheapest and most effective way of improving
CPU performance. Having a larger RAM reduces
virtual memory thus improving performance
Factors affecting Processing speed
 4. Reducing virtual memory:
 What is Virtual memory:
 When you open a program or application. You don’t need
to access all the contents of the program at once. You
only need a partial amount of features of the program.
Vast majority of the application is actually unused.
Unused content of the RAM is returned to the hard disk
which is called virtual memory. Essentially swapping
data from RAM to hard disk forms Virtual memory. Too
much swapping reduces performance. Because too much
capacity wasted on moving data than actual read/write
Increasing RAM reduces virtual memory
 If you have a 1 GB RAM.
You want to open a 500
MB application.150 MB
is swapped in from the
hard disk to the RAM on
startup. So 350 MB is
returned to the hard
disk. So 350 MB is the
virtual memory in this
RAM.
 Increased virtual
memory will reduce
performance
 If you have a 2 GB RAM.
You want to open a 500
MB application. 300 MB
is swapped in from the
hard disk to the RAM on
startup. So 200 MB is
returned to the hard
disk. So 200 MB is the
virtual memory in this
RAM
 Reduced virtual memory
will increase
performance
Factors affecting Processing speed
 5. Increasing internal clock: The internal clock
of a processor defines the speed of the processor. If
we have a 3.3 GHz processor that means the clock of
the processor process 3.3 billion cycles per second.
 Clock is made of a quartz crystal whose materail is
silica(SiO2- silicon di oxide). same material that is
sand made of.
 Piezo-Electric effect: if you apply electricity to the
crystal. The crystal will vibrate at a fixed frequency.
Factors affecting Processing speed
 The CPU ticks at 3.3 billion times per second just as
our watch ticks at 1 second interval.
 It also indicates the transistors in the processor will
switch ON/OFF 3.3 billion times every second.
 It also means each cycle of the clock takes 1/3.3
billion second.
 1 cycle of the clock=0.3 nanosecond.
Factors affecting Processing speed
 6. Width of BUS:
 Bus is the parallel wires that connect different parts
of the CPU: Bus is like the highway system that
connects different cities. So if we have wider
highways e.g. 8 lane highway will transport more
cars than 4 or 2 lane highway. So a 32 bit bus will
process twice the among data than a 16 bit processor,
everything else held constant.
Factors affecting Processing speed
Factors affecting Processing speed
 7. Clock frequency of bus:
 If a processor has bus of 3.2 GHz whereas the data bus
has 800 MHz then there will be a delay or lag. Processor
and data bus clock frequencies are equally important.
 8. Having larger cache memory:
 operating principle of cache memory:
 When CPU needs to read a data, it first checks whether it
is already stored in cache memory before swapping it in
from RAM, if it is already not there then CPU reads the
data from RAM to registers, at the same time leaves a
copy in the cache. So next time if CPU needs the data it
can find it in cache memory.
Cache memory
 as different parts of computer has different speed.
If you sort from higher to lower speed then
 Processor is faster than Cache
 Processor>Cache>RAM>Hard disk drive>CDROM player>Floppy disk Drive
 So to cope with extremely fast processor, a fast speed
cache memory is installed in between processor and
RAM.
Cache memory
 Cache memory is made of static RAM whereas usual
RAM is made of Dynamic RAM.
 DRAM packs one bit per transistor but SRAM packs
only one bit for 3 or 4 transistors.
 That’s why SRAM is faster because it is dense but
more expensive also smaller than DRAM.
 DRAM or RAM is slower than cache memory or
SRAM. But RAM is larger than cache memory also
less expensive than RAM in terms of cost per bit.
Cache memory cont.
 3 types of cache
 1. Level 1( L1): built onto CPU, holds recently run
data.
 2. Level 2(L2): holds potential upcoming data.
Intel, AMD found that if L2 cache is built onto CPU
it greatly increases performance.
 Level 3(L3): holds possible data. built on
motherboard found only on server and
workstations.
Factors affecting Processing speed
Factors affecting Processing speed
Factors affecting Processing speed
Factors affecting Processing speed
Various bus standards
 1. ISA(Industry Standard Architecture)-16 bit bus
developed by IBM used on IBM PC/XT. ATA bus
renamed to be used on IBM PC/AT running Intel
80286 processor. Backward-compatible with 8-bit
systems. 32 bit version was not popular. Gang of 9- 9
competing PC clone manufacturers developed
Extended ISA.
 2. Local Bus: it is a bus that connects CPU with
external devices directly.
 3. PCI(Peripheral Component Interface)- a 32-bit 33
MHz local bus standard developed by Intel though
not tied to any processor. It has a clock speed of 33
MHz to run at 32 bit. It can run 64 bit at 66 MHz.
Motherboards employ ISA for slower devices and
PCI for faster devices. In 1993 Intel and Microsoft
designed Plug-and-Play ISA(called ISA PnP) so that
any device driver can be installed automatically.
Later PCI express was developed to connect high
speed devices mostly broadband internet connection
such as Gigabit Ethernet, also USB 2.0 devices.
 4.AGP-Accelerated Graphics Port)- 32 bit 2.1 GHz
bus to connect high speed graphics card and video
card made by graphic chip divisions of Intel, AMD,
Nvidia, ATI(Array Technology Inc.Canada, later
acquired by AMD.
 5. USB(Universal Serial Bus)-480 MHz , 32 bit and
hot swappable to connect newer devices. Best feature
127 daisy chain connected devices.
Daisy chain devices
 5. Firewire (Apple’s version of IEEE 1394 but incresingly used
on PC): 400 MHz 32 bit hot swappable bus to connect high
data speed devices such as video camera, digital TV. In 2011
Apple started to replace Firewire with Thunderbolt.
 Firewire allows peer to data communication e.g. sanner to
printer data transfer.
 It has 80% capacity for Iso-synchronous(fixed data)and 20 %
capacity for asynchronous(variable data). That’s why it is
popular in aircraft data communications, also used in Internet
connection over FireWire, digital camera, Digital Video
Recorders, cable TV boxes, iPod and iPhone 3GS charging
dropped in favor of USB.
 NB: AGP, USB 2.0, FireWire faster bus due to high clock
speed of 2.1 GHz, 480 and 400 MHz
 7. PC CardBus: 32 bit, 33 MHz same as PCI bus
only
difference hot swappable, size of Credit card. Used for
NIC(network Interface Card), Modems, Wi-Fi cards, usually
used for notebook/laptops. Mostly No longer used due to
popularity of USB bus.
 3 types of PC card
Type I: flash, RAM, Cache storage and memory devices
Type II: Networking
Type III: Small 2.5” inch Hard disk drives instead of the regular
3.5” inch HDD.
Type III is thicker than Type II and Type II is thicker than Type
I
CompactFlash flash memory device is a smaller version of PC
Card.