Hardware Abstraction Layer - HAL

[mamta mohanty]

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Hardware Abstraction Layer

GEAR HOBBING

Gears transmit power or motion mechanically between parallel, intersecting, or non-intersecting shafts. Millions of gears are produced each year in sizes from a few millimeters up to more than 30 ft. in diameter. Often the requirements that must be, and are routinely, met in their manufacture are amazingly precise. Consequently, the machines and processes that have been developed for producing gears are among the most ingenious we have.

Physical requirements of gears:-

1) The actual tooth profile must be same as the theoretical one.
2) Tooth spacing must be uniform and correct.
3) The actual and theoretical pitch circles must be
coincident.
4) The face and flank surfaces must be smooth.

Gear hobbing is done for the production of spur, helical worm gears, splines, sprockets, ratchet wheel & any other form that can be hobbed.
STUDY OF GEAR HOBBING MACHINES

HEWKS Universal Gear Hobbing Machine Model V-60

The heavy duty Universal Gear Hobbing Machines represents the ultimate in sound uptodate design. These are of precision construction with superior workmanship which ensures high output and fine performance. The machine can cut spur Gears, Helical Gears, Worm Gears, Splines, Serration sprocket Wheels, Ratchet Wheels and any other form that can be hobbed. The bed and main column of the machines are of ample size. These are of box type design and are well ribbed with V-type guideways. For the consistence accuracy of the machine axially adjustable Indexing worm is provided to remove backlash. Provision has also been made to remove backlash in feed screw and nut of the Hob slide. Oil reservoirs are provided in the machine which ensures thorough lubrication of Gears & Bearings.

[jopl88]

Hardware Abstraction Layer - HAL

HAL is Microsoft's abbreviation for the Hardware Abstraction Layer, the technology and drivers that let the Windows NT, 2000, and XP operating systems communicate with your PC's hardware. HAL is one of several features--along with the NT file system (NTFS) that replaced the much less secure MS-DOS--that make NT-based operating systems more secure and reliable than Windows 95, 98, and Me.

HAL prevents applications from directly accessing your PC's system memory, CPU, or hardware devices (such as video and sound cards)--a method that can prevent many device conflicts and crashes. Unfortunately, HAL sometimes also slows or stops DOS games and programs, which need to load their own memory managers or control hardware directly for better performance.

With HAL in the way, developers must rewrite or even abandon their older software in favor of newer, HAL-compatible versions. Microsoft has pressured hardware makers to provide or support technologies such as MMX, DirectX, and 3D graphics language OpenGL, all of which allow fast but indirect access to the advanced high-performance features of video, sound, and CPU hardware.

Such access also makes for a better visual experience when using Windows for Web and productivity applications; improved graphics performance is evident all over Windows XP's new user interface.XP also offers some new compatibility-mode features that let you run programs meant to run under earlier operating systems, but, frankly, most DOS-based and even some Windows-based games simply won't work with the new OS.

Tips: To see which HAL is currently installed, open Device Manager, and expand the Computer branch. The entry that appears in this branch corresponds to the currently installed HAL.