Abstract: A method comprises storing pixel data in a frame buffer, retrieving the pixel data from the frame buffer and processing at least one pixel value of the pixel data to generate an output pixel bit stream. The method further comprises storing pixel values in a first update buffer. The pixel values are derived from the output pixel bit stream. The method also comprises providing the pixel values from the first update buffer across a network to a remote graphics system.

Abstract: A method comprises storing pixel data in a frame buffer, retrieving the pixel data from the frame buffer and processing at least one pixel value of the pixel data to generate an output pixel bit stream. The method further comprises storing pixel values in a first update buffer. The pixel values are derived from the output pixel bit stream. The method also comprises providing the pixel values from the first update buffer across a network to a remote graphics system.

Abstract: A rotary valve (10) of an internal combustion engine, of the hollow cylindrical type for rotation in the bore (20) of the cylinder head of the engine, the valve (10) having oil and gas seals (17,14) to prevent leakage of oil to the combustion chamber and leakage of gas from the combustion chamber, each gas seal being of the piston ring type and each oil seal consisting of a non-rotating annular member (17), a seal (21) between it and the bore in which the valve (10) rotates, an annular cavity (24) lying peripherally in a small radial clearance between the valve (10) and the bore (20) and extending between the gas sealing ring (14) and the seal (21) on the annular member (17), the annular member (17) having a substantially radially disposed face (18) arranged to seal slidingly against a radially disposed face (19) on the valve (10), the quality of these faces (18,19) being such as to allow migration of oil between them but sufficient when combined with the radial depth of the faces (18,19) to prevent oil from