Lecture : Computer Hardware. – A thorough look at the components contained in a typical PC. Covering various material from Chapters 1,2, 3 & 4
Review from previous Lecture – Inside the Computer.
Lecture Overview
We
will discuss what you should know before buying a computer. We will describe the components that are
contained in a typical PC. We will look
at the standard and specialty features of each component. We will have greater insight into why
computers vary greatly in price.
List
the standard measurements for computer components.
Throughput
= (Bus Speed x Bus Size)/8
(measured in bytes/sec)
Ex. PCI Bus
(33,000,000 x 32)/8
= 132MB/sec
PCI 2 Bus (66,000,000 x 64)/8 =
528MB/sec
List
the components of a typical system
Case
Motherboard
RAM
CPU
Video Card
Sound Card
Hard Drive
Floppy Drive
Optical Drive - CD ROM, CD -
R, CD -RW, DVD, DVD-R
Modem
Network Card
Monitor
Keyboard
Mouse
Speakers
Definitions:
Bus - An electrical pathway through which the
processor sends data and commands to RAM and all peripheral devices.
Slot - A receptacle that houses a processor chip,
expansion card or memory module and provides an interface to a system or I/O
bus.
Port - An access point in a computer system that permits
communication between the computer and a peripheral device.
Socket - A receptacle that houses a CPU.
Case
The case houses most of the components of a computer system. They are generally equipped with a fan(s) and power supply. Large Cases are needed for servers that will have many disks and other peripheral devices. These larger cases have upward to 400W power supplies. A smaller cases, Mini-Tower or desktop, will have a power supply of about 230 - 250W.
Variations in price stem from power, fan, and
materials used.
Motherboard
An extremely important component and one that is often left unmentioned in marketing materials.
The motherboard houses the CPU and memory. It contains the buses, ports and slots that
the CPU uses.
Lower priced boards may have fewer or slower buses,
ports and slots and may be made thin or poorly constructed.
High priced boards will have many and faster buses,
ports and slots
The motherboard also contains a set of chips (called
a chip set) that assists the processor when the processor communicates to RAM,
Cache and BUS devices.
To get a better understanding of these variation
let’s look at buses, ports and slots.
Show Clock, Bus1 and Bus2 avi
files
Buses
System Bus – This is the pathway that the CPU uses to communicate with RAM and Cache. I will discuss this more when I talk about CPUs.
I/O Buses
Sometimes referred to as expansion buses, because they allow you to expand your computer system to include additional devices.
ISA Bus 16 bit, 8Mhz bus used to support slower peripherals, such as keyboard, mouse, modem, and floppy drive. This bus has mostly been phased out, however, previously, it was the main I/O bus.
PCI Bus - originally a 32bit, 33Mhz (132MBytes/sec) bus used to support faster devices, such as hard drives, CD-ROM drives, graphic adapters, network adapters and SCSI devices. PCI version 2.2 doubled the original spec to 64bit, 66 Mhz bus and is capable of transferring data at 528MBytes/sec (version 2.2 is still emerging in the market place).
PCI Express - the PCI Express bus is a bidirectional serial bus that was developed due to limitations in the design of the parallel PCI bus. PCI Express 1x bus achieves throughput of 250MB/sec. The PCI 16x achieves speeds that are 16x faster, or 4GB/sec.
USB Universal Serial Bus – rides over the PCI Bus and permits up to 127 USB devices to be connected in a daisy chain to it. Can pass up to 12Mbits/sec (1.5MB/sec) through its interface. It also uses a single interrupt, so, it is generally much easier to install a USB device on a PC then an ISA device. It is a “hot plug” bus, allows you to install devices on the fly. USB 2.0 operates 40x faster than the original spec - 480Mbits/sec (60MB/sec).
SCSI Small Computer System Interface Bus – rides over the PCI Bus and allows up to 15 SCSI devices to be connected in a daisy chain to it. There are variations to the SCSI interface that support data transfers at speeds from 5MBytes/sec to 320MBytes/sec. Also uses a single interrupt.
1394 or FireWire Bus – Another “hot plug”, single interrupt bus. Allows up to 63 devices to be daisy chained to it and can transfer up to 400Mbit/sec (50MBytes/sec). A useful bus for supporting high bandwidth external devices such as video cameras. Popular in Apple computers.
AGP Bus - a 32bit, high speed bus used to support graphic processing and display. The AGP bus has been upgraded several times.
AGP – operates at 66MHz (achieves (266MB/sec)
AGP 2x – operates at 133MHz (achieves 532MB/sec)
AGP 4x – operates at 266MHz (achieves 1064MB/sec)
AGP 8x – operates at 533MHz (achieves 2.1GB/sec)
Slots
A motherboard comes with several slots. A slot connects to a bus on the motherboard. Expansion boards are inserted into the slots. A typical motherboard may have 3 PCI slots, 1 ISA slots and 1 AGP slot.
Ports
Often a motherboard may contain built in ports or accept an expansion card that will contain ports. Ports are links to the computer's bus. An external device is connected to a port that is housed on an expansion card or motherboard. The port connector is usually specifically designed for a particular device. For example:
Serial ports typically use a 9 or 25 pin connector to transfer data one bit at a time – serially
Parallel ports typically use 25 pin RS 232 or 36 pin Centronics connector to transfer data eight bits at a time over 8 parallel data lines
SCSI, USB, 1394, Ethernet, keyboard, mouse and IrDa (infrared) are all ports with specialized connectors.
Sockets
The motherboard houses the CPU. The CPU is inserted into a socket.
CPU
Described in terms of word size – the amount of data that is handled as a unit, and speed in MHz. Speed translates into MIPS, BIPS, GigaFLOPs, and TeraFLOPs. Also, playing an important role in the speed of system bus width and speed, and Cache that the CPU is designed around.
CPU Processors
Comparison
Chipsets - Central processors (CPUs) work hand in
hand with a set of chips that perform I/O
processing (inputting and outputting data to peripheral devices. Chipsets significantly impact overall system
throughput. The following highlights the
important features of chipsets relating to throughput.
Show CPU Diagrams
Bus_Diagram
Computer_Diagram
AMD and Intel Chipsets
PC Processor Costs
The processor contributes heavily to the disparity in overall cost of PC systems. The latest and greatest processors cost significantly more than last quarter’s leader.
The best way to measure the relative differences between these systems is with benchmark tests. Ziff Davis has developed a series of benchmark test devised to determine how a machine will perform under various work environments. ZD BusinessWinStones. ZD Business Graphic WinMarks, ZD CPUmark32 are some of the benchmark tests.
Data Storage
A CPU needs to store programs and data for use while it is powered up and running.
Memory
Discuss the various types: RAM, Cache, ROM, PROM
RAM abundant, fast.
Cache small, very fast.
ROM small slow, non-volatile (firmware) Used to store information that seldom or never changes. (Ex. Boot program, disk drive specs)
PROM programmable
RAM
Show Simm1.avi
Temporary, volatile memory used by the processor. Nearly everything gets loaded into RAM – programs, data, results. The CPU uses RAM extensively.
Types of memory modules:
SIMMs single in-line memory modules, 32 bit, various densities
DIMMS dual in-line memory modules, 64 bit, various densities
DDR SDRAM are DIMMS that handle 64 bits at up to 400MHz. They yield 3.2GB/sec throughput)
RIMMS or RAMBUS memory, 16 bit and operates up to 1066MHz. They operate over 2 channels and yield over 4 GB/sec throughput
RAM Cost
The cost of memory has dropped 20% per year over the last 20 years. Capacity has quadrupled every 3-½ years over the last 20.
Secondary Storage
Secondary Storage devices are used to permanently store files. There are various kinds of files. Ultimately files are just zeroes and ones. However, the zeros and ones are stored is a predefined format. Format defines file type. Executable program, data, graphic, audio, video are all types of times of files.
Show Tourfor.avi describes formating
Secondary storage speeds are measured in 1/1000th of a second, compared to CPU speeds that are measured in 1/1,000,000,000 of a second. Roughly a million times slower.
Hard Drives
Controllers are needed to run hard drives and EIDE controller goes for about $20, SCSI controllers go for about $190
Density typically is in the 40 - 80GB range.
Access speed, the time it takes to position the read/write heads over the area of the disk you would like to read or write to, is around 4 - 8 milliseconds.
Transfer speeds depend on rotational speed and sometimes cache chips that are located on the disk controller. Higher end drives spin at 7200rpms.
Types of drives and controllers:
SCSI I, II & III - SCSI supports both 8 and 16 bit transfer. Transfer speeds are:
8 16
SCSI I 5MBytes/sec
SCSI II 10MBytes/sec 20MBytes/sec
SCSI III 20MBytes/sec 40MBytes/sec
With synchronous burst rates that are twice the above.
ATA drives are common PC drives and have a transfer rate of 33/66/100MBytes/sec.
SATA is the latest drive interface. It achieves 150Mbytes/sec throughput.
Floppy Drives
These drives can store up to 1.44MB of data. Access times are extremely slow
Memory Keys
Memory keys are solid state storage devices that store between 64MB – 128MB of data. They are functionally equivalent to floppy disks in that they enable you to easily move data from one computer to the next. They are roughly the size of key and they interface to a computer through the USB port.
Zip Drives
The advantage of ZIP is portability and is also useful for backup. Comes in 100MB, 250MB and 750MB versions.
The the Jazz version stores up to 2 GIG
Optical Drives
Lasers are used to etch pits into the surface of optical drives. Pits and lands (lands are un-etched surfaces) represent 1’s and 0’s.
CD-ROMs are popular optical drives. They can store up to 650MB in standard format (roughly equivalent to the information stored in a 20 volume encyclopedia). They are categorized by their access speeds (32x, 40x, 75x). A 75x drive spins 75 times faster than an audio CD and can transfer up to 11.25MB/sec. (An audio CD can transfer only 150KB/sec)
DVD is an emerging favorite and will likely overtake CD-ROM. DVD offers higher densities and is now writable. DVD’s can store data on either one or both sides of the disk and on one or two layers per side. A single sided, single layer DVD can store 4.7GB. A double sided, double layered DVD can store 17GB, 4 times more data.
DVD drives can also read CD, CD-R, CD-RW. They have slow access speeds 135ms in DVD mode and 85ms in CD mode. They have built in MPEG decoding and support CD, CDR (CD recordable), CDRW (CD re-writeable) and DVD media.
DVD-R are now becoming less costly and as a result, more popular. DVDs that support re-writes (lied CD-RWs) are also call DVD-RAM.
FMD is an emerging high-capacity drive that will store up to 140GB of data.
Video Accelerators
Show Fvidcard.avi
Video accelerators connect using the PCI AGP bus. They have an on board chip set that contains a video processor that runs at speeds of 250HMz or more. Prices vary depending up the chip set and the amount of RAM on the card. The better cards support screen resolutions up to 1900x1200 pixels per inch. Some AGP cards support 128-bit processing. Some are fitted with 64bit processors in the chip set. Some cards have special functions such as video editing.
Sound Cards
Show Soundcrd.avi
Use both ISA and PCI slot interface.
Sound Cards offer 32 bit processing and 3D surround sound.
Modems
Use both ISA and PCI slot interface. Special feature modem cards are designed to handle voice and data calling.
Monitors
Probably the easiest component to select. What you see is what you get.
The faster the refresh the better, the lower the dot pitch the better, the bigger the screen the better (so they say).
The refresh rate and the resolution work together. Some monitors will not support the highest resolutions and the highest refresh rates - generally in the range from 60Hz - 80Hz.
Flat Screen monitors are the most costly.
Keyboard and Mouse
Generally low cost items unless you opt for wireless
High and Low End Costs Comparison
Low-end system is a good choice for someone who intends to use the system for MS Office applications and browsing the Internet.
High-end system is a good choice for someone who wants the best because they see computing as entertainment and tool (gamers), or someone who needs the best for Graphic applications or other processor intensive applications.
Discuss components from a consumer's view.
Consumer Advice
· Start with a firm budget
· Compare these things – Processor, bus speed, amount of RAM, hard disk size, other storage devices, monitor, speakers, printer, software bundle, warrantee.
· Select the best system for your dollar
· Consider both processor speed and front-side bus speed when determining the best system
· Don’t get hung up on buying the very best – it takes about 3 months for the top of the line processor to fall to the mid-range.
· If you are upgrading a base system, upgrade RAM first.
· DVD, CD-R, CD-RW drives are highly useful. A DVD/CD-RW/CD-R drive is money well spent.
· Make sure you have the peripherals you need. Package the audio, video, and printing that will match your needs. For example, if you are using your computer for home entertainment a large monitor, large speakers would be desirable. Also, if you are interested in digital photograph, a quality printer is desirable.
· Don’t forget to consider how you will connect to the Internet – modem, DSL, cable.