wh212减速机壳体加工工艺及夹具设计【最新】

wh212减速机壳体加工工艺及夹具设计【最新】内容摘要：

PCI cards plug into . SCSI—The small puter system interface is a method of adding additional devices, such as hard drives or scanners, to the puter. AGP—Accelerated Graphics Port is a very highspeed connection used by the graphics card to interface with the puter. Sound card—This is used by the puter to record and play audio by converting analog sound into digital information and back again. Graphics card—This translates image data from the puter into a format that can be displayed by the monitor. Connections No matter how powerful the ponents inside your puter are ,you need a 攀枝花学院机电工程学院毕业设计专用纸 14 way to interact with them. This interaction is called input/output(I/O). The most mon types of I/O in PCs are Monitor—The monitor is the primary device for displaying information from the puter. Keyboard—The keyboard is the primary device for entering information into the puter. Mouse—The mouse is the primary device for navigating and interacting with the puter Removable srorage—Removale storage devices allow you to add new information to your puter very easily, as well as save information that you want to carry to a different location Floppy disk—The most mon form of removable storage , floppy disks are extremely inexpensive and easy to save information to . CDROM—CDROM(pact disc, readonly momory) is a popular form of distribution of mercial software. Many sysrems mow offer CDR (recordable) and CDRW(rewritable), which can also record . Flash memory—Based on a type of ROM called electrically erasable programmable readonly memory (EEPROM), Flash memory provides fast, permanent storage. Compact Flash, Smart Media and PCMCIA cards are all types of Flash memory. DVDROM—DVDROM is similar to CDROM but is capable of holding much more information Ports Parallel—This port is monly used to connect a printer. Serial—This port is typically used to connect an external modem. Universal Serial Bus (UBS)—Quickly being the most popular external connection, UBS ports offer power and versatility and are incredibly easy to use FireWire(IEEE1394)—FireWire is a very popular method of connecting digital video devices, such as camcorders or digital cameras, to your puter. Inter/work connection Modem—This is the standard method of connecting to the Iner Local area work(LAN) card—This is used by many puters, particularly those in an Ether office work, to connected to each other. Cable modem—Some people now use the cabletelevision system in their home to connect to the Inter Digital Subscriber Line(DSL) modem—This is a highspeed connection that works over a standard telephone line Very high bitrate DSL(VDSL) modem—A newer variation of DSL, VDSL require that your phone line have fiberoptic cables. From Powerup to Shutdown Now that you are familiar with the parts of a PC, let us see what happens in a typical puter session, from the moment you turn the puter on until you shut it down. You press the ―On‖ button the puter and the monitor. 攀枝花学院机电工程学院毕业设计专用纸 15 You see the BIOS software doing its thing , called the power selftest(POTS). On many machines, the BIOS displays text describing such data as the amount of memory installed in your puter and the type of hard disk you have .During this boot sequence, the BIOS does a remarkable amount of work to get your puter ready to run. The BIOS determines whether the video card is operational. Most video cards have a miniature BIOS of their own that initializes the memory and graphics processor on the card. If they do not ,there is usually videodriver information on the another ROM on the motherboard that the BIOS can load The BIOS checks to see if this is a cold boot or a reboot. It does this by checking the value at memory address0000: value of 1234h indicates a reboot, in which case the BIOS skips for the rest of POST. Any other value is considered a cold boot If it is a cold boot , the BIOS verifies RAM by performing a read/write rest of each memory address, it checks for a keyboard and a mouse. It looks for a PCI bus and , if it finds one , checks all the PCI cards . If the BIOS finds any errors during the POTS, it notifies you with a series of beeps or a text message dosplayed in the screen. AN error at this point is almost a hardware problem. The BIOS looks at the sequence of storage devices identified as boot devices in the COMS Setup. ―Boot‖ is short for ―bootstrap‖, as in the old phrase ―Lift yourself up by your bootstraps.‖ Boot refers to the process of launching the operating system. The BIOS tries to initiate the boot sequence from the first device using the bootstrap loader. The bootstrap loader loads the operating system into memory and allows it to begin system, user information and applications. The bootstrap loader then establishes the data structures that are used to municate within and between the subsystem and application of the puter .Finally, it turns control of the puter over to the operating system. Once loaded , the operating system’s tasks fall into six broad categories:  processor management—breaking the tasks down into manageable chunks and priotitizing them before sending to the CPU.  Memory management—coordinating the flow of data in and out of RAM and determining when virtual memory is necessary.  Device managementproviding an interface between each divice connected to the puter,the CPU and applications  Storage management—Directing where data will be stored permanently on hard drives and other forms of storage .  Application interfaceProviding a standard munications and data exchange between software programsand the puter.  User Interfaceproviding a way for you to municate and interact with the puter. When you choose the ―shut down‖option, the opreating sys。