Abstract: A high speed printing system including a host computer, a printer controller and a print engine. The printing system can operate in a normal mode where a high level page description language is used to convey page information from the host computer to the printer controller. The system further permits rasterization of a page to be printed at the host computer and the downloading of rasterized page data to the printer controller in a form that the data can be directly serialized to the print engine.

Abstract: In an apparatus and method for performing perspective interpolation of texture coordinates in computer graphics, an incremental interpolation technique is used to calculate the pixel values along a display line from the associated texture map. The incremental technique is based on Bresenham's algorithm adapted for use with hyperbolae. On the basis of the parameters of the start and end pixels of a span along a display line, a set of interpolation test parameters is set and the texel coordinates for the current pixel are tested against these parameters to determine whether they are still valid for the next pixel. If they are not valid, the test parameters are updated and the texel coordinates are incremented and retested. This process is repeated until the correct texel is identified.

Abstract: Bidirectional communications between a host computer and a selected printer connected to the host, either locally or by way of a network, are used to provide a user of the host with access to a substantially real-time, visual and functional replica of the operator panel of the selected printer. A user at the host computer may also visually monitor the status of multiple printers at the same time from the same host display.

Abstract: In an image-data processing apparatus, halftoning or dither values are generated by performing operations on initial "seed" values. In one example, this is done within the registers in the central processing unit, thereby avoiding the need for repetitive, and time consuming, access to a memory external to the central processing unit.

Abstract: A slot ventilator (100, 500) comprises a slotted backing member (24, 124, 424, 524), an elongate facing strip (26, 126, 426, 526, 626), and a linkage mechanism connecting the backing member and facing strip with one another, the linkage mechanism being arrange to permit generally translational forward and backward movement of the facing strip between a closed position in which the slot is closed and an open position in which the facing strip is spaced in front of the backing member. The linkage mechanism includes a hinge (58, 158, 300) allowing the facing strip to rotate about a longitudinal axis to vary the angular orientation thereof. When installed horizontally in a window frame (14, 588, 588') the facing strip may be moved forwards and backwards to increase and decrease ventilation, and may be rotated about the hinge to divide incoming ventilation favourably between downward and upward directions.

Abstract: Bidirectional communications between a host computer and a printer connected to the host, either locally or by way of a network, are used to provide a user of the host with access to a substantially real-time, visual and functional replica of the operator panel of the printer. The user may view the replica to access all data available through the printer operator panel. Using a mouse or other input device, the user of the host computer can also effectively actuate any pushbuttons or other operator panel control devices depicted as part of the replica.

Abstract: A computer and printer system in which communication between the computer and printer can be carried out in either a bidirectional mode or a unidirectional mode. As disclosed, the computer operates in a single-threaded multi-tasking environment in which a printer control utility application runs to facilitate bidirectional communication with an attached printer. The application program maintains the computer parallel port in a bidirectional communication and printing mode, but is capable of taking the parallel port out of this mode in order to perform unidirectional printing, either from another application operating in the multi-tasking environment or from a DOS session running in the environment. The printer control utility prevents the mixing of unidirectional and bidirectional print jobs through the parallel port.

Abstract: Apparatus for discharge handling metal sheets from a rack consists of a pair of tiltable tables, plan dimensioned to telescope inside the rack when the latter is lowered over the tables; each table has a vertically disposed stop and a vertically positioned member slidable towards the stop. A pull down for the rack ensures that the sheets which are supported by spaced apart pins are lowered sufficiently below the tables to free the sheets from the pins at which time the slidable members move each to their respective stop to pack the sheets. The tables are then tilted until the stops are horizontal and the slidable members retract after which the packs are moved off the tables on to adjacent loading stations.

Abstract: An ion microprobe has an ion extraction arrangement formed by a pair of cone-shaped guard electrodes. The guard electrodes are positioned to lie tangentially to each other and to a planar surface from which ions are extracted with their apexes coinciding at the point of extraction. They have equal apex angles of preferably 90.degree.. An aperture is provided at the common apex and electric fields oppositely polarized with respect to each other are provided within each guard electrode for ion and electron beam extraction.