硬體概論

Introduction to Computer Hardware


Pellaeon Lin @ CCCA

outline 概覽

  1. Motherboard
  2. CPU:    CISC, RISC
  3. RAM:   DDR1-3
  4. Storage:   Optical discs, HDD, SSD
  5. Graphics:   Graphic Cards, D-SUB, DVI, HDMI
  6. Network:   Ethernet, Fiber Optics
  7. Peripherals:   USB, Thunderbolt, eSATA, 1394
  8. Power Supply

motherboard 主機板

主要用途是連結電腦的各個元件，

如 CPU, RAM, USB


現今的主機板還會將整合一些基本功能，

如 網卡、音效卡、顯示卡、一些常見的界面卡


常見的桌上型電腦的主機板尺寸：

  • ATX, microATX:  一般桌機
  • *ITX:  小型桌機（準系統）


主機板上的元件：晶片組 (Chipset)


晶片組的用途就是作爲 CPU 與其他元件溝通的橋樑


通常不同的 CPU 會有不同的晶片組




來看看主機板規格～

Gigabyte GA-X79-UP4


CPU - Central processing unit

這就是電腦的腦！


CPU 的用途，當然就是做數學運算與邏輯運算了


CPU 有很多種指令集，可分爲兩類：CISC 與 RISC

其中目前最廣泛使用於 PC 與伺服器的指令集就是 x86 了

生產 x86 CPU 的廠商有2大家：Intel 和 AMD

instruction set

An instruction set, or instruction set architecture (ISA), is the part of the computer architecture related to programming, including the native data types, instructions, registers, addressing modes, [...]. An ISA includes a specification of the set of opcodes (machine language), and the native commands implemented by a particular processor.

microarchitecture

Microarchitecture, also called computer organization, is the way a given instruction set architecture (ISA) is implemented on a processor. A given ISA may be implemented with different microarchitectures. Implementations might vary due to different goals of a given design or due to shifts in technology. Computer architecture is the combination of microarchitecture and instruction set design.


CISC - Complex instruction set computing

A complex instruction set computer is a computer where single instructions can execute several low-level operations (such as a load from memory, an arithmetic operation, and a memory store) and/or are capable of multi-step operations or addressing modes within single instructions.

Well known CISC families

  • z/Architecture: used in IBM zSeries mainframe computers
  • x86: As the term became common after the introduction of the 80386, it usually implies binary compatibility with the 32-bit instruction set of the 80386. This may sometimes be emphasized as x86-32 or x32 to distinguish it either from the original 16-bit "x86-16" or from the 64-bit x86-64. Although most x86 processors used in new personal computers and servers have 64-bit capabilities, to avoid compatibility problems with older computers or systems, the term x86-64 (or x64) is often used to denote 64-bit software, with the term x86 implying only 32-bit.

RISC -Reduced instruction set computing

RISC is a CPU design strategy based on the insight that simplified (as opposed to complex) instructions can provide higher performance if this simplicity enables much faster execution of each instruction.

Well known RISC families

  • ARM: Often seen in smartphone and tablet computers.
    An ARM processor needs much fewer transistors compared to CISC processors, resulting in low power usage.
    - Used by most of the Android phones, iPhone, iPad
  • Power (including PowerPC and Cell):
    PowerPC is used by early generations (roughly before 2005) of Apple laptops and desktops.
    Cell is used by game consoles such as PS3 and Xbox 360

 CPU Clock rate (Frequency)

We use clock rate to determine CPU speeds, its unit is Hertz (Hz), 1 Hz means the CPU can complete 1 instruction per second. Modern PC CPUs can have clock rate up to 4Ghz (Gigahertz), although 2~3 Ghz is more common.

Actual clock rate of CPU is determined by 2 factors, external clock and the clock multiplier, where:

Clock rate = external clock * clock multiplier

External clock is the clock of front side bus (FSB) and is usually few hundred Mhz. (1000Mhz = 1Ghz)

Clock multiplier is usually a integer from 4 to 10.


northbridge

Increasingly functions of northbridge have migrated to the CPU chip itself, beginning with memory and graphics controllers. For Intel Sandy Bridge and AMD Fusion processors introduced in 2011, all of the functions of the northbridge reside on the CPU.

southbridge

Intel's Haswell, expected to be available in 2013, is expected to feature the southbridge (Platform Controller Hub) on the same package as the CPU for the Ultrabook platform.



Let's take a look at some CPUs

intel

AMD

RAM - Random-Access Memory

There are 2 types of RAM, DRAM and SRAM. I will be mainly talking about DRAM.

PC use DRAM as their main memory, as they are much cheaper than SRAM of the same size. (Main memory is often referred as RAM)

SRAM is used in CPU caches (L1, L2, L3), since DRAM can't reach the speed demand of CPUs.

Dual in-line memory module (DIMM) comprises a series of DRAM integrated circuits.

DDR SDRAM*

A bus transfers data at each clock cycle, each time transferring data size of the bus width. (modern memory buses have bus width of 64bits)

DDR stands for double data rate, a computer bus operating with double data rate transfers data on both the rising and falling edges of the clock signal.

For instance, a DDR2-800 memory has a frequency of 400Mhz, 800MT/s transfer rate, 64bits (8byte) bus width, thus have a theoretical bandwidth of 800*8=6400MB/s



cont.*

SDRAM stands for Synchronous DRAM, which means its clock is synchronized with the system bus.

Multi-channel memory architecture


Multi-channel memory architecture is a technology that increases the transfer speed of data between the DRAM and the memory controller (which regulates data flow between the CPU and system memory) by adding more channels of communication between them. Theoretically this multiplies the data rate by exactly the number of channels present.

Ganged versus unganged

Dual-channel was originally conceived as a way to maximize memory throughput by combining two 64-bit buses into a single 128-bit bus. This is retrospectively called the "ganged" mode. However, due to lackluster performance gains in consumer applications as discussed above, more modern implementations of dual-channel use the "unganged" mode by default, which maintains two 64-bit memory buses but allows independent access to each channel, in support of multithreading with multi-core processors.

Secondary Storage

Secondary storage, differs from primary storage in that it is not directly accessible by the CPU. The computer usually uses its input/output channels to access secondary storage and transfers the desired data using intermediate area in primary storage. Secondary storage does not lose the data when the device is powered down—it is non-volatile. Per unit, it is typically also two orders of magnitude less expensive than primary storage. Consequently, modern computer systems typically have two orders of magnitude more secondary storage than primary storage and data are kept for a longer time there.

Hard disk drive (HDD) - Structure

HDD - Size

A sector is the smallest storage unit that is addressable by a hard drive, and all information stored by the hard drive is recorded in sectors. The most common physical sector size for harddisks today is 512 bytes.

1 kilobyte (KB) = 103 bytes, 1 kibibyte (KiB) = 210 bytes

1 megabyte (MB) = 106 bytes, 1 mebibyte (MiB) = 220 bytes

1 gigabyte (GB) = 109 bytes, 1 gibibyte (GiB) = 230 bytes


HDD - Filesystems

A filesystem is an abstraction to store, retrieve and update a set of files. The term also identifies the data structures specified by some of those abstractions, which are designed to organize multiple files as a single stream of bytes.

The filesystem manages access to the data and the metadata of the files, and manages the available space of the device(s) which contain it. Ensuring reliability is a major responsibility of a file system. A file system organizes data in an efficient manner, and may be tuned to the characteristics of the backing device.

Filesystems


- Linux : ext3, ext4, btrfs, XFS

- FreeBSD : UFS, ZFS

- Windows : NTFS, FAT, exFAT

- Mac : HFS+

RAID - redundant array of independent disks

  • RAID0: Provides improved performance and additional storage but no fault tolerance. Simply put, RAID0 combines a few disks into one big logical disk.
  • RAID1: data is written identically to two drives, thereby producing a "mirrored set". With appropriate operating system support, there can be increased read performance, and only a minimal write performance reduction.
  • RAID5: provides fault tolerance of 1 drive failures. Upon drive failure, any subsequent reads can be calculated from the distributed parity such that the drive failure is masked from the end user. However, a single drive failure results in reduced performance of the entire array until the failed drive has been replaced and the associated data rebuilt. RAID5 requires at least 3 disks.
  • RAID6: Like RAID5, but with double parity, thus provides fault tolerance of 2 drive failures. Double parity gives additional time to rebuild the array without the data being at risk if a single additional drive fails before the rebuild is complete. RAID6 requires at least 4 disks.



Nice RAID table on Wikipedia >

Optical disc drive

Optical disc drive (ODD) is a disk drive that uses laser light or electromagnetic waves within or near the visible light spectrum as part of the process of reading or writing data to or from optical discs.


Solid-state drive (SSD) is a data storage device that uses integrated circuit assemblies as memory to store data persistently. SSD technology uses electronic interfaces compatible with traditional block input/output (I/O) hard disk drives. SSDs do not employ any moving mechanical components, which distinguishes them from HDDs. Compared with electromechanical disks, SSDs are typically less susceptible to physical shock, are usually silent, and have lower access time and latency. However, while the price of SSDs has continued to decline in 2012, SSDs are still about 10 times more expensive per unit of storage when compared to HDDs.

HDD interfaces

Video card

A video card (also called a video adapter, display card, graphics card, graphics board, display adapter or graphics adapter) is an expansion card which generates a feed of output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors (multi-monitor).

Integrated Video card

Modern low-end to mid-range motherboards often include a graphics chipset manufactured by the developer of the northbridge (e.g. an AMD chipset with Radeon graphics or an Intel chipset with Intel graphics) on the motherboard. This graphics chip usually has a small quantity of embedded memory and takes some of the system's main RAM, reducing the total RAM available.

Video Cards Interfaces

Display Interfaces

network interface cards

  • Ethernet: 10/100/1000 Mbits
    Usually PCI (consumer) or PCIe (servers)
    Ethernet usually uses 8P8C(often mistakenly called RJ45) as its connector
  • Wireless: 802.11a/b/g/n
    Usually PCI or USB


Some high-end NICs are capable of TCP offloading, which could lower CPU load, because the NIC would help process TCP packets.

Optical Fibres

Peripherals


Interfaces with Direct Memory Access (DMA) such as Thunderbolt and FireWire are subjected to DMA attacks, in which the computer's main memory may be manipulated by a malicious device.

Power Supply

A power supply unit (PSU) converts mains AC to low-voltage regulated DC power for the internal components of a computer.

Most modern desktop personal computer power supplies conform to the ATX specification, which includes form factor and voltage tolerances. While an ATX power supply is connected to the mains supply, it always provides a 5 V standby (5VSB) voltage so that the standby functions on the computer and certain peripherals are powered. ATX power supplies are turned on and off by a signal from the motherboard.


Q & a

If you would like to ask privately, mail me at pellaeon@cnmc.tw

You could always ask later on
nctu_nba@googlegroups.com


Thank you!

introduction to computer hardware

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