Apparatus for generating the display of a cursor

Claim 3

Apparatus for performing the method according to claim 1 or 2, characterized b y: a.) means (34,36,38) for specifying the form of the cursor and the address of the origin of the cursor; b.) means (40,42) for comparing the address of the origin of the cursor with the adress of each pixel of the raster as each pixel is scanned and producing a signal identifying the time at which the address of a pixel being scanned equals the address of the origin; c.) means (44,50) for utilizing said signal to identify each pixel corresponding to a cursor pixel location; d.) means (46,52,48) for producing a cursor control signal each time a pixel is scanned, the location of which corresponds to a selected one of the cursor pixel locations for the specified form; and e.) means (54)responsive to each cursor control signal for causing the color look-up memory to produce color control signals said color control signals causing the pixel being scanned when a cursor control signal is produced to be displayed in the selected cursor color and at the selected cursor intensity.

Claim 4

Apparatus for generating a cursor for display by a color raster graphic system said cursor having predetermined boundaries, and including all pixel positions of the raster of the system within its boundaries, one of said pixel positions being designated as the origin of the cursor, said cursor having a plurality of forms, said system including a graphic controller (10) for producing binary signals for controlling the operation of the raster graphic system and raster scan logic (20) for producing the addresses of the pixels substantially as scanned, said addresses including the x and y coordinates of the pixels of the raster, characterized by.: a.) means (36,38) for storing an address of a pixel with which the origin of the cursor is to coincide; b.) means (40,42) for comparing the x and y coordinates of the address of the origin of the cursor stored in the means for storing an address with the x and y coordinates address of each pixel as produced by the raster scan logic (20) and for producing an address compare signal when the x or y coordinates of both addresses are the same; c.) an addressable memory (56) for storing a cursor control bit for each cursor position for each form of the cursor; and d.) means (44-54) responsive to the address compare signals for forming addresses of cursor control bits for one form of the cursor stored in said addressable memory (56), for reading out of said memory cursor control bits stored at each addressed location, and for producing a cursor control bit as each pixel is scanned which corresponds to a pixel position of the cursor, cursor control bits having a given predetermined binary value adapted to cause the pixel being scanned by the system to be displayed in a predetermined color and with a predetermined intensity.

Claim 5

Apparatus according to Claim 4, characterized in that the addressable memory (56) for storing cursor control bits is a read-only memory.

Claim 6

Apparatus according to Claim 5, characterized in that the addressable memory (56) for storing cursor control bits stores four control bits at each addressable location.

Claim 7

Apparatus according to Claim 4, characterized in that the number of forms of the cursor is four.

Claim 8

Apparatus for generating a cursor for display by a color raster graphic system, said cursor having predetermined boundaries and including all pixel positions of the raster of the system within its boundaries, one of the pixel positions being designated as the origin of the cursor, said cursor having a plurality of forms, said system including a graphic controller for producing binary signals for controlling the operation of the raster graphic system and raster scan logic for producing binary addresses of the pixels substantially as scanned for an interlaced display, said addresses including the x and y coordinates of the pixels of the raster, the least significant bit of the y coordinate being an odd/even frame bit, comprising: a) cursor number latch means (34) for storing a cursor number; b) a cursor vertical coordinate latch (36) for storing the y coordinate of the address of the origin of the cursor; c) a cursor horizontal coordinate latch (38) for storing the x coordinate of the address of the origin of the cursor; d) a vertical comparator (40) for comparing the higher order bit positions of the y coordinates of the cursor origin stored in the vertical latch and the higher order bit positions of the y coordinate of the address of the pixel being scanned as produced by the raster scan logic and for producing a vertical compare signal when they are the same; e) a horizontal comparator (42) for comparing the x coordinate of the cursor origin stored in the horizontal latch and the x coordinate of the pixel being scanned as produced by the raster scan logic and for producing a horizontal compare signal when they are the same; f) circuit means (44,50) to which the vertical and horizontal compare signals are applied for producing a vertical enable signal and a horizontal enable signal; g) an addressable memory (56) for storing a cursor control bit for each cursor position for each form of the cursor, the binary address including the form number, a y component and a x component; h) vertical counter means (52,52') for producing the higher order bit positions of the y component of the cursor address when enabled by a vertical enable signal; i) exclusive OR gate means (68) to which the least significant bit of the y coordinate of the origin of the cursor stored in the vertical position latch and the frame bit of the y coordinate of the pixel being scanned are applied, the output of the exclusive OR- gate being the least significant bit of the y component of the address applied to the cursor memory (56); j) means (70) for delaying the production of the vertical enable signal for one horizontal sweep cycle when the least significant bit of the origin of the cursor is a logical one and the frame bit of the pixel being scanned is a logical zero; k) horizontal counter means (46) for producing the x component of the cursor address when enabled by the horizontal enable signal; 1) a cursor enable gate (48) which produces a cursor enable signal when the vertical enable signal and horizontal enable signal are both present; and m) shift register means (54) to which the lower order bits of the x component of the cursor address and the cursor control bits stored in each addressable location of the cursor memory are applied, for producing a cursor control bit as each pixel is scanned which corresponds to a pixel position of the cursor, cursor control bits having predetermined binary value adapted to cause the pixel being scanned to be displayed in a predetermined color and with a predetermined intensity.