Abstract: A display processor in a raster graphics display system includes a transformation, clipping and mapping feature which controls the transformation, clipping and mapping of graphics data. A control byte contains 5 bits identified as: M--Window to viewport mapping; P--perspective projection; D--2D/3D mode; T--transformation; and C--clipping. Each bit in the control byte is tested to determine what operations are to be performed on the figure to be drawn.

Abstract: A technique for efficiently drawing wide lines in a graphics display system by method and apparatus which includes identifying a wide line to be drawn; drawing a first line of pixels of a wide line; determining if a next line in the wide line has a different first coordinate value from a first coordinate value of the first line; generating at least one additional pixel value for the next line if the first coordinate value of the next line is different from the first coordinate value of an immediately previously drawn line; repeating the steps until the wide line has been completely drawn.

Abstract: A method for clipping fixed characters against one or more clipping boundaries for display in a graphics display system, includes the steps of: storing fixed characters to be displayed; defining a window in a first coordinate space against which said characters shall be clipped along one or more boundaries thereof; clipping an inverse character box for each fixed character to be displayed against said defined clipping window; and transforming said clipped character box defined in a first coordinate space to a character box defined in a second coordinate space for display on a graphics display system.

Abstract: A prefetching mechanism for a system having a cache has, in addition to the normal cache directory, a two-level shadow directory. When an information block is accessed, a parent identifier derived from the block address is stored in a first level of the shadow directory. The address of a subsequently accessed block is stored in the second level of the shadow directory, in a position associated with the first-level position of the respective parent identifier.With each access to an information block, a check is made whether the respective parent identifier is already stored in the first level of the shadow directory. If it is found, then a descendant address from the associated second-level position is used to prefetch an information block to the cache if it is not already resident therein. This mechanism avoids, with a high probability, the occurrence of cache misses.

Abstract: In graphics display systems the use of matrix concatenation for coordinate transformation, occasionally, will cause an overflow which may represent an out-of-bounds location of a data element. To correct the overflow problem, a number of translation shift factors are introduced for the last row of the matrix which when used to operate on matrix elements, will maintain the elements within the physical boundaries of the graphics base by preventing overflow. Additionally, a method of adjusting the clipping boundaries to increase the precision of coordinate transformations is also described. The methods of the invention may be implemented in microcode in a commercially availably graphics display system such as the IBM 5080 Graphics System.

Abstract: Method and apparatus for providing interpolated display characteristic values, such as intensity or Z value, for pels within a polygon to be displayed by a computer graphics display system. A scanning sequence generates pel addresses such that each pel address so generated is contiguous with a previously generated pel address. The parametric value rate of change in both the X and the Y direction is determined, and expressed as an integer value and a remainder quantity. The remainder quantity is used to determine a sequence, driven by pel address changes, by which the integer parametric value increment from pel to pel is incremented or decremented by one in a regular sequence that assures that the error in the computed parametric value for each pel never exceeds 0.5 parametric value units.

Abstract: Assuming that a given equation representing a quadratic curve is:F(x, y)=ax.sup.2 +bxy+cy.sup.2 +dx+ey+f=0,the method for generating quadratic curve signals repeatedly selects a point close to F (x, y)=0 in only one of either the region of F (x,y).gtoreq.0 or the region of F (x,y)<0. This method allows to generate quadratic curve signals by using only a few parameters and without using complicated calculations. A hardware implementation is also disclosed.

Abstract: A high speed multiplier includes a logic circuit for performing multiplication a multiplicand stored in a first resister and a multiplier stored in a second register, which includes means connected to the second register for selectively gating a selected portion of a multiplier stored in the second register to a recoding means; shift gate means connected to outputs of the first register and controlled by outputs of the recoding means to gate selected groups of multiples of the multiplicand to an adder means for adding a group of multiples of the multiplicand under the control of the control signals; means for accumulating successive intermediate products generated by the adder means; spill adder means, connected to the means for accumulating, for generating a low order portion of a final result of the multiply; storage means for storing the low order portion of the final result; means for generating a high order portion of the final result from outputs of the means for accumulating; and means for storing the

Abstract: A programmable, sequential logic array for performing logical operations within a memory array, including an input storage array having addressable locations for storing input control words, input means for receiving a plurality of input signals and control words from the input storage array and producing signals indicating the relationship between conditions of the input signals and conditions represented by the control words, output means for providing binary output signals, an output storage array having addressable locations for storing output control words for controlling a state of the output means, a next address storage array for identifying a next address from one of a plurality of fields within the next address array, address generation means for receiving address signals from the next address storage array and for applying the address signals to address circuits of the input storage array, the output storage array, and the next address storage array, coding means for coding status of lines comprisi

Abstract: Method and apparatus for filling convex polygons for display in a raster graphics system is described. Starting from the bottom of the polygon, horizontal lines are drawn to fill the polygon as y-value increments. A polygon-fill processor includes two modified Breshenham line generators.

Abstract: A multiprocessing system is presented for dynamically partitioning a storage module into a global storage efficiently accessible by a number of processors connected to a network, and local storage efficiently accessible by individual processors, including the interleaving of storage references output by a processor, under the control of that processor, and dynamically directing the storage references to first or second portions of the storage module.

Abstract: A channel interface multiple virtual control unit controls a plurality of classes of terminal sessions on a graphics system workstation, the multiple virtual control unit includes lookup tables having indicia related to a class of display session to be enabled for controlling a workstation in either a alpha-numeric display mode or a graphics display mode.

Abstract: A security module for use in an electronic funds transfer terminal is contained in a tamper-resistant housing. The module has a PIN pad and is designed to encrypt secret data, such as users personal identity numbers (PINs), so that other terminal processes cannot gain access to it. The encryption functions are carried out in a security controller which includes its own microprocessor and encryption/decryption unit.

Abstract: In an interactive graphics display system in which pels in a frame buffer are mapped to the display screen of a raster display device, a method of automatically highlighting and de-highlighting graphic segments as a cursor is moved across the display screen comprises sampling a locator device at successive points in time to generate a screen cursor at corresponding positions on the screen, examining pels in the frame buffer along a line which extends from the pel corresponding to the previous cursor position to the pel corresponding to the current cursor position to determine whether a pel is "on" along the line, automatically performing a correlate operation in respect of the "on" pel (if any) to identify the graphic segment associated with that pel, and highlighting the segment so identified, any highlighted segment being de-highlighted prior to highlighting a different segment.

Abstract: A high content LCD includes, a glass plate; a polysilicon deposited substrate supporting a matrix of electrodes; each of the electrodes defining a picture element (pel) in the LCD; a liquid crystal material interposed between the glass plate and the substrate; a plurality of FET devices, there being one or more FET device associated with each of the electrodes; and means for selectively actuating the FET devices to display an image on the LCD.

Abstract: A method for rotation of a binary image by 180 degrees, includes the steps of: positioning first and second address pointers at the center of at the beginning and end respectively of an image to be rotated; indexing the first pointer in a first direction through said image; indexing the second pointer in a second direction through said image; exchanging, for each index step, a first image word at the first pointer with a second image word, at the second pointer if the first image word and the second image word have any two bits with different values; reversing all exchanged words; storing the reversed, exchanged words at said pointer locations; repeating the above steps until the first pointer and the second pointer have been indexed through all words in the image at which point the image has been rotated by 180 degrees.