Handbook Phần Cứng PU part 27 pptx

As their complexity and need for updates grew, BIOS firmware was stored on EEPROM or flash memory devices.. If the boot block detects that the main BIOS is corrupt, then it will typicall

ROM with BIOS

BIOS is sometimes called firmware Before 1990 or so BIOSes were held on ROM chips that could not be altered As their complexity and need for updates grew, BIOS firmware was stored on EEPROM or flash memory devices This EEPROM chip sits on a FWH interface, but in some newer boards EEPROM chips are

already sitting on a newer, emerging interface named SPI EEPROM chips are advantageous because they can easily be updated by the user; however, an

improperly executed or aborted BIOS update can render the computer or device unusable To avoid BIOS corruption, some new motherboards have a backup BIOS ("Dual BIOS" boards) Also, most BIOSes have a "boot block" which is a portion

of the ROM that runs first and is not updateable This code will verify that the rest

of the BIOS is intact (via checksum, hash, etc.) before jumping to it If the boot block detects that the main BIOS is corrupt, then it will typically boot to a floppy

so that the user can try flashing again, hopefully with a better image Hardware manufacturers frequently issue BIOS updates to upgrade their products and remove bugs

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Firmware on adapter cards

A computer system can contain several BIOS firmware chips The motherboard BIOS typically contains code to access fundamental hardware components such as the keyboard, floppy drives, ATA (IDE) hard disk controllers, USB human

interfaces, and storage devices In addition, plug-in adapter cards such as SCSI, RAID, Network interface cards, and video boards often include their own BIOS, complementing or replacing the system BIOS code for the given component

In some devices that can be used by add-in adapters and actually directly integrated

on the motherboard, the add-in ROM may also be stored as separate code on the main BIOS flash chip It may then be possible to upgrade this "add-in" BIOS

(sometimes called an "option ROM") separately from the main BIOS code

Add-in cards usually only require such an add-in BIOS if they:

 Need to be used prior to the time that the operating system loads (e.g they may be used as part of the process which loads (bootstraps) the operating system), and:

 Are not sufficiently simple, or generic in operation to be handled by the main BIOS directly

Older operating systems such as DOS, as well as bootloaders, may continue to make use of the BIOS to handle input and output However, most modern

operating systems will interact with hardware devices directly by using their own device drivers to directly access the hardware Occasionally these add-in BIOSes are still called by modern operating systems, in order to carry out specific tasks such as preliminary device initialization

To find these memory mapped expansion ROMs during boot, PC BIOS

implementations scan real memory from 0xC8000 to 0xF0000 on 2 kilobyte

boundaries looking for a 0x55 0xaa signature, which is immediately followed by a byte indicating the number of 512 byte blocks the expansion ROM occupies in real memory The BIOS then jumps to the offset immediately after the size byte, at which point the expansion ROM code takes over and uses BIOS services to

provide a user configuration interface, register interrupt vectors for use by post-boot applications, or display diagnostic information

For UNIX and Windows/DOS systems there is a utility with which you can dump your BIOS firmware software at http://www.linuks.mine.nu/ree/

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The BIOS boot specification

If the expansion ROM wishes to change the way the system boots (such as from a network device or a SCSI adapter for which the BIOS has no driver code), it can use the BIOS Boot Specification (BBS) API to register its ability to do so Once the expansion ROMs have registered using the BBS APIs, the user can select

among the available boot options from within the BIOS's user interface This is why most BBS compliant PC BIOS implementations will not allow the user to enter the BIOS's user interface until the expansion ROMs have finished executing and registering themselves with the BBS API

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The Fall and Rise of the BIOS

Older operating systems such as DOS called on the BIOS to carry out most input-output tasks within the PC; with the introduction of newer operating systems such

as Microsoft Windows and Linux, the BIOS was relegated to principally providing initial hardware setup, and bootstrapping Once it was up and running, the

operating system didn't have to rely on the BIOS for much

In recent years, however, by way of systems such as ACPI, the BIOS has taken on more complex functions such as aspects of power management, hotplug, thermal management etc This has led to renewed reliance on the BIOS by operating

system producers, and an increase in complexity in the BIOS code This in turn has led to invention of Intel's modern Extensible Firmware Interface (EFI) which in itself incorporates BIOS's extended options Microsoft announced that support for EFI in Windows Vista will be dropped for the launch, but added in a later update for 64 bit version, leaving only Linux and OS X as the operating systems that widely use it nowadays

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The BIOS business

The vast majority of PC motherboard suppliers license a BIOS "core", and toolkit from a commercial third party, which creates and maintains such a core The

motherboard manufacturer then customizes this BIOS to suit its own hardware - for this reason updated BIOSes are normally obtained directly from the

motherboard manufacturer

Graphics processing unit

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GeForce 6600GT (NV43) GPU

Radeon 9800 Pro (R350) GPU

A Graphics Processing Unit or GPU (also occasionally called Visual Processing Unit or VPU) is a dedicated graphics rendering device for a personal computer,

workstation, or game console Modern GPUs are very efficient at manipulating and displaying computer graphics, and their highly parallel structure makes them more effective than typical CPUs for a range of complex algorithms

A GPU implements a number of graphics primitive operations in a way that makes running them much faster than drawing directly to the screen with the host CPU The most common operations for early 2D computer graphics include the BitBLT operation (combine two bitmap patterns using a RasterOp), usually in special

hardware called a "blitter", and operations for drawing rectangles, triangles,

circles, and arcs Modern GPUs also have support for 3D computer graphics, and typically include digital video-related functions as well

Contents

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 1 History

o 1.1 1970s

o 1.2 1980s

o 1.3 1990s

o 1.4 2000 to present

 2 Computational Functions

 3 GPU Forms

o 3.1 Dedicated Graphics Cards

o 3.2 Integrated Graphics Solutions

 4 GPU manufacturers

 5 See also

 6 External links

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History

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1970s

Modern GPUs are descended from the monolithic graphic chips of the late 1970s and 1980s These chips had limited BitBLT support in the form of sprites (if they had BitBLT support at all), and usually had no shape-drawing support Some

GPUs could run several operations in a display list, and could use DMA to reduce the load on the host processor; an early example was the ANTIC co-processor used

in the Atari 800 and Atari 5200 In the late 1980s and early 1990s, high-speed, general-purpose microprocessors became popular for implementing high-end

GPUs Several high-end graphics boards for PCs and computer workstations used TI's TMS340 series (a 32-bit CPU optimized for graphics applications, with a frame buffer controller on-chip) to implement fast drawing functions; these were especially popular for CAD applications Also, many laser printers from Apple shipped with a PostScript raster image processor (a special case of a GPU) running

on a Motorola 68000-series CPU, or a faster RISC CPU like the AMD 29000 or Intel i960 A few very specialised applications used digital signal processors for 3D support, such as Atari Games' Hard Drivin' and Race Drivin' games