Raster scan display apparatus for dynamically viewing image elements stored in a random access memory array

• US RE31,200 E
• Filed: 10/09/1979
• Issued: 04/05/1983
• Est. Priority Date: 01/19/1976
• Status: Expired due to Term

• Current Assignee: Marine Midland Business Loans, Inc.
• Original Assignee: Xtrak Corporation
• Inventors: Sukonick, Josef S., Tilden, Greg J.
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US06/082,592
• Time in Patent Office: 1,274 Days
• Field of Search: 340/709, 340/721, 340/725, 340/726, 340/731, 340/734, 340/793, 340/798, 340/799
• US Class Current: 345/24
• CPC Class Codes: G09G 2340/12 Overlay of images, i.e. displayed pixel being the result of switching between the corresponding input pixels
• CPC Class Codes: G09G 5/346 for systems having a bit-mapped display memory
• CPC Class Codes: G09G 5/39 Control of the bit-mapped memory
• CPC Class Codes: G09G 5/391 Resolution modifying circuits, e.g. variable screen formats
• CPC Class Codes: G09G 5/393 Arrangements for updating the contents of the bit-mapped memory
• CPC Class Codes: G09G 5/42 characterised by the display of patterns using a display memory without fixed position correspondence between the display memory contents and the display position on the screen

Abstract

A computer graphics display system including random access raster memory for storing data to be displayed, a raster memory control unit for writing data into the raster memory, a video control unit for causing such information to be displayed on a CRT display screen, a micro control unit for controlling the function and timing of the raster memory control unit and the video control unit, and a computer adapter for facilitating data exchange between the micro control unit and a host computer. The displayed image can have extremely high complexity with essentially no problem of display flicker. Zoom and pan features allow the use of a very complex stored image in a flexible manner, and a split-screen technique enables an operator to work on a very complex picture at a detail level while still having an overview of the total picture, or any portion thereof, simultaneously presented before him. The split-screen feature also allows the simultaneous display of alphanumeric messages such as prompts, menus, or X-Y readouts added to the graphics display and a small area of the raster memory is usually reserved for this purpose. An XOR feature allows a selective erase that restores lines crossing or concurrent with erased lines. The XOR feature permits part of the drawing to be moved or "dragged" into place without erasing other parts of the drawing.

Claims

1. storage sites..]. 2. A computer graphics display system .[.as recited in claim 1 wherein said video control means includes,.]. .Iadd.for use in association with a host computer to provide a visual display of graphics information contained therein, comprising:

a data bus;

an address bus;

display means for developing a visible image corresponding to video signals input thereto;

channel adapter means for providing an interface for communicating information including bits of graphics data between the host computer and said data bus and said address bus;

system control means communicatively coupled to said data bus and said address bus and operative to generate first and second control signals;

raster memory means including an array of N rows and M columns of storage sites each capable of storing a bit of graphics data corresponding to a picture element of a graphics image to be formed by said display means;

raster memory control means communicatively coupled to said address bus, said data bus, said raster memory means and said system control means, said raster memory control means being responsive to said first control signal and operative to cause bits of graphics data input from the host computer to be stored in said raster memory means;

video control means communicatively coupled to said address bus, said data bus, said raster memory means, said display means, and said system control means, said video control means being responsive to said second control signal and operative to read out in raster fashion data stored in any selected block of n rows and m columns of said storage sites, where n is an integer less than N and m is an integer less than M, and to use such data to generate a video signal for input to said display means whereby said display means is caused to display an image comprised of picture elements corresponding to the data obtained in the selected block of storage sites;

said video memory control means including;

.Iaddend.

a first control memory for storing a first set of readout control instructions received from said system control means;

a second control memory for storing a second set of readout control instructions received from said system control means;

readout means for reading out bits of graphics data stored in said raster memory means; and

1ogic means for causing said readout means to read out data stored in a first selected block of storage sites of said raster memory means under control of said first set of instructions and to read out data stored in a second selected block of storage sites of said raster memory means under control of said second set of instructions, the data read out of said first and second blocks of storage sites being included in said video signal and said display means being caused to simultaneously display a first image corresponding to the data from said first block and a second

2. image corresponding to the data from said second block. 3. A computer graphics display system as recited in claim 2 wherein said video control means further includes,

cursor control logic for generating a cursor signal;

and

video mixer means for mixing said cursor signal and the data from said first and second blocks to develop said video signal. .[.4. A computer graphics display system as recited in claim 1 wherein said video control means includes zoom control logic for controlling the number of times each bit of data is to be consecutively read out of said raster memory means by said readout means whereby data read out a first number of times will be displayed at a first scale and data read out a second number of times will

3. be displayed at a second scale different from said first scale..]. 5. A computer graphics display system .[.as recited in claim 1 wherein said video control means includes,.]. .Iadd.for use in association with a host computer to provide a visual display of graphics information contained therein, comprising:

a data bus;

an address bus;

display means for developing a visible image corresponding to video signals input thereto;

channel adapter means for providing an interface for communicating information including bits of graphics data between the host computer and said data bus and said address bus;

system control means communicatively coupled to said data bus and said address bus and operative to generate first and second control signals;

raster memory means including an array of N rows and M columns of storage sites each capable of storing a bit of graphics data corresponding to a picture element of a graphics image to be formed by said display means;

raster memory control means communicatively coupled to said address bus, said data bus, said raster memory means and said system control means, said raster memory control means being responsive to said first control signal and operative to cause bits of graphics data input from the host computer to be stored in said raster memory means;

video control means communicatively coupled to said address bus, said data bus, said raster memory means, said display means, and said system control means, said video control means being responsive to said second control signal and operative to read out in raster fashion data stored in any selected block of n rows and m columns of said storage sites, where n is an integer less than N and m is an integer less than M, and to use such data to generate a video signal for input to said display means whereby said display means is caused to display an image comprised of picture elements corresponding to the data obtained in the selected block of storage sites;

said video control means including;

.Iaddend.

grid generator means for generating grid signals for display by said display means; and

video mixer means for mixing said grid signals with the data read out of said selected block to develop said video signal whereby the displayed image includes a background grid having a predetermined positional

4. relationship to the displayed graphics data. 6. A computer graphics display system .[.as recited in claim 1 wherein said video control means includes,.]. .Iadd.for use in association with a host computer to provide a visual display of graphics information contained therein, comprising:

a data bus;

an address bus;

display means for developing a visible image corresponding to video signals input thereto;

channel adapter means for providing an interface for communicating information including bits of graphics data between the host computer and said data bus and said address bus;

system control means communicatively coupled to said data bus and said address bus and operative to generate first and second control signals;

raster memory means including an array of N rows and M columns of storage sites each capable of storing a bit of graphics data corresponding to a picture element of a graphics image to be formed by said display means;

raster memory control means communicatively coupled to said address bus, said data bus, said raster memory means and said system control means, said raster memory control means being responsive to said first control signal and operative to cause bits of graphics data input from the host computer to be stored in said raster memory means;

video control means communicatively coupled to said address bus, said data bus, said raster memory means, said display means, and said system control means, said video control means being responsive to said second control signal and operative to read out in raster fashion data stored in any selected block of n rows and m columns of said storage sites, where n is an integer less than N and m is an integer less than M, and to use such data to generate a video signal for input to said display means whereby said display means is caused to display an image comprised of picture elements corresponding to the data obtained in the selected block of storage sites;

said video control means including;

.Iaddend.

1ogic means for enabling the boundaries of said block of storage sites to be incrementally changed so as to cause the corresponding display to

5. appear to pan across the raster memory means. 7. A computer graphics display system as recited in claim 6 wherein said system control means includes means for limiting the area of said raster memory means over

6. which said boundaries may be incrementally changed. 8. A computer graphics display system as recited in claim 2 wherein said logic means includes.Iadd.;

first .Iaddend.means for determining when all data from said first block has been read out, .[.and.]. .Iadd.second means, cooperating with said first means, .Iaddend.for causing said system control means to load a third set of read out control instructions into said first control memory.Iadd., said logic means causing said readout means to read out data stored in a third selected block of storage sites of said raster memory means under control of said third set of instructions, .Iaddend.and .[.for determining.]. .Iadd.third means, operative .Iaddend.when all data from .[.a.]. .Iadd.said .Iaddend.third block of storage sites has been read out, .[.and.]. for causing said system control means to reload said first set of control instructions back into said first control memory, .Iadd.said logic means .Iaddend.thus causing said display means to simultaneously display first, second and third images corresponding to the first, second and third blocks of data.

7. A computer graphics display system .[.as recited in claim 1 wherein said raster memory control means includes.]. .Iadd.for use in association with a host computer to provide a visual display of graphics information contained therein, comprising:

a data bus;

an address bus;

display means for developing a visible image corresponding to video signals input thereto;

channel adapter means for providing an interface for communicating information including bits of graphics data between the host computer and said data bus and said address bus;

system control means communicatively coupled to said data bus and said address bus and operative to generate first and second control signals;

raster memory means including an array of N rows and M columns of storage sites each capable of storing a bit of graphics data corresponding to a picture element of a graphics image to be formed by said display means;

raster memory control means communicatively coupled to said address bus, said data bus, said raster memory means and said system control means, said raster memory control means being responsive to said first control signal and operative to cause bits of graphics data input from the host computer to be stored in said raster memory means;

video control means communicatively coupled to said address bus, said data bus, said raster memory means, said display means, and said system control means, said video control means being responsive to said second control signal and operative to read out in raster fashion data stored in any selected block of n rows and m columns of said storage sites, where n is an integer less than N and m is an integer less than M, and to use such data to generate a video signal for input to said display means whereby said display means is caused to display an image comprised of picture elements corresponding to the data obtained in the selected block of storage sites;

said raster memory control means including;

.Iaddend.

means for inputting data into selected ones of said storage sites and for causing such data input to sites presently occupied by other data to be

8. logically exclusive ORed. .[.10. A computer graphics display system as recited in claim 1 wherein said display means is capable of developing a multicolored image and said raster memory means further includes another array of N rows and M columns of storage sites each directly corresponding to a storage site of said first mentioned array, corresponding memory sites of the respective arrays being adapted to receive data which jointly constitute a binary code identifying the color of an image component corresponding thereto;

and wherein said video control means includes

means for simultaneously reading out data from corresponding storage sites of said arrays to develop a series of binary signals;

decoding means for decoding said binary signals and developing a plurality of decoded signals corresponding thereto;

hue memory means responsive to said decoded signals and operative to develop a plurality of corresponding color component signals; and

video mixing means for combining said color component signals to develop a

9. color video signal for driving said display means..]. 11. A computer graphics display system as recited in claim 8 wherein said raster memory control means includes means for causing data selectively input to said raster memory means at sites presently occupied by other data to be logically exclusive ORed. .[.12. A computer graphics display system as recited in claim 1 wherein said raster memory control means includes zig-zag control logic for causing a block of data to be read into said raster memory means in a predetermined zig-zag pattern defined by a single set of coordinate points identifying one corner of the block of data..].

10. A computer graphics display system .[.as recited in claim 1 wherein said raster memory control means includes.]. .Iadd.for use in association with a host computer to provide a visual display of graphics information contained therein, comprising:

a data bus;

an address bus;

display means for developing a visible image corresponding to video signals input thereto;

channel adapter means for providing an interface for communicating information including bits of graphics data between the host computer and said data bus and said address bus;

system control means communicatively coupled to said data bus and said address bus and operative to generate first and second control signals;

raster memory means including an array of N rows and M columns of storage sites each capable of storing a bit of graphics data corresponding to a picture element of a graphics image to be formed by said display means;

raster memory control means communicatively coupled to said address bus, said data bus, said raster memory means and said system control means, said raster memory control means being responsive to said first control signal and operative to cause bits of graphics data input from the host computer to be stored in said raster memory means;

video control means communicatively coupled to said address bus, said data bus, said raster memory means, said display means, and said system control means, said video control means being responsive to said second control signal and operative to read out in raster fashion data stored in any selected block of n rows and m columns of said storage sites, where n is an integer less than N and m is an integer less than M, and to use such data to generate a video signal for input to said display means whereby said display means is caused to display an image comprised of picture elements corresponding to the data obtained in the selected block of storage sites;

said raster memory control means including;

.Iaddend.

skip pattern control means for periodically inhibiting a storage operation in a predetermined manner so as to prevent certain bits of the graphics data appearing on said data bus from being stored in said raster memory

11. means. 14. A computer graphics display system as recited in claim 13 wherein said skip pattern control means includes a skip pattern memory for storing a plurality of predetermined skip pattern commands, and logic means controlled by said system control means and operative to select one of said skip pattern commands and to generate a first signal in accordance

13. operation. 16. A computer graphics display system .[.as recited in claim 1 wherein said video control means includes.]. .Iadd.for use in association with a host computer to provide a visual display of graphics information contained therein, comprising:

a data bus;

an address bus;

display means for developing a visible image corresponding to video signals input thereto;

channel adapter means for providing an interface for communicating information including bits of graphics data between the host computer and said data bus and said address bus;

system control means communicatively coupled to said data bus and said address bus and operative to generate first and second control signals;

raster memory means including an array of N rows and M columns of storage sites each capable of storing a bit of graphics data corresponding to a picture element of a graphics image to be formed by said display means;

raster memory control means communicatively coupled to said address bus, said data bus, said raster memory means and said system control means, said raster memory control means being responsive to said first control signal and operative to cause bits of graphics data input from the host computer to be stored in said raster memory means;

video control means communicatively coupled to said address bus, said data bus, said raster memory means, said display means, and said system control means, said video control means being responsive to said second control signal and operative to read out in raster fashion datastored in any selected block of n rows and m columns of said storage sites, where n is an integer less than N and m is an integer less than M, and to use such data to generate a video signal for input to said display means whereby said display means is caused to display an image comprised of picture elements corresponding to the data obtained in the selected block of storage sites;

said video control means including;

.Iaddend.

sync generator means for generating a hashing pulse train and .[.a dot clock generator.]. .Iadd.hashing logic means .Iaddend.responsive to said hashing pulse train .[.and operative to cause.]. .Iadd.for causing .Iaddend.said video signal to be pulsed on and off to cause the display to

14. appear to have a matt background. 17. A computer graphics display system comprising:

video signal generating means for developing a raster signal including a plurality of scan lines each divided into a plurality of equal signal periods containing information corresponding to picture elements of an image to be displayed;

hashing means for periodically disabling the output of said generating means so as to blank said raster signal during a predetermined portion of each said signal period; and

video display means responsive in the periodically blanked raster signal and operative to develop a visual image corresponding thereto such that the said blanking of said raster signal causes the displayed image to

12. therewith for periodically inhibiting said storage operation. 15. A computer graphics display system as recited in claim 14 wherein said skip pattern control means further includes modulo arithmetic logic means for generating a second signal for perodically inhibiting said storage

18. n×

m arrays to said second n×

m array. 22. A computer graphics display system as recited in claim .Iadd.20 or .Iaddend.21 wherein each of the said n×

m arrays respectively contains data relating to phased still graphics of a cartoon to be animated, and said system further includes means for cyclically reading out in a predetermined series the data from said arrays so as to create in the display an illusion of

15. appear to have a matt background. .[.18. A computer graphics system for displaying in raster fashion an image comprised of an n×

m array of picture elements, comprising;

raster memory means including a data storage array having N rows and M columns of data storage sites;

means for providing a selectable first origin address signal for designating the origin site of a first n×

m array of storage sites in said raster memory means, where n is an integer less than N and m is an integer less than M;

clock generating means for generating first, second and third clock signals, said first clock signal including Zm signal pulses for each signal pulse of said second clock signal, and said second clock signal including Zn signal pulses for each signal pulse of said third clock signal, where Z is any positive integer;

means responsive to said first origin address signal and said first second and third clock signals and operative to start at the origin site of said first n×

m array and read out data from m storage sites in each of the n rows of said first n×

m array;

raster means for developing a raster scan signal from the data read out of said first n×

m array; and

display means responsive to said raster scan signal and operative to display an image corresponding to the data contained in said first n×

m array..]. .[.19. A computer graphics system as recited in claim 18 and further comprising;

means for providing a second origin address signal for designating the origin site of a second n×

m array of storage sites in said raster memory means;

means responsive to said second origin address signal and said first, second and third clock signals and

operative to start at the origin site of said second n×

m array and read out data from m storage sites in each of the n rows of said second n×

m array; and

wherein said raster means also develops another raster scan signal from the data read out of said second n×

m array and said display means also responds to said other raster scan signal to display the data contained in

23. said second array. 28. A computer graphics display system .[.as recited in claim 18 and further comprising:

.]. .Iadd.for displaying in raster fashion an image comprised of an n×

m array of picture elements, comprising;

raster memory means including a data storage array having N rows and M columns of data storage sites;

means for providing a selectable first origin address signal for designating the origin site of a first n×

m array or storage sites in said raster memory means, where n is an integer less than N and m is an integer less than M;

clock generating means for generating first, second and third clock signals, said first clock signal including Zm signal pulses for each signal pulse of said second clock signal, and said second clock signal including Zn signal pulses for each signal pulse of said third clock signal, where Z is any positive integer;

means responsive to said first origin address signal and said first, second and third clock signals and operative to start at the origin site of said first n×

m array and read out data from m storage sites in each of the n rows of said first n×

m array;

raster means for developing a raster scan signal from the data read out of said first n×

m array;

display means responsive to said raster scan signal and operative to display an image corresponding to the data contained in said first n×

m array;

.Iaddend.

means for generating a grid signal including a series of pulses occurring in a series of regular timed intervals; and

means for synchronously mixing said grid signals with the data read out of said n×

m array so that the displayed image includes a background grid which has a predetermined positional relationship to the data

19. animated cartoon motion. 23. A computer graphics display system as recited in claim .Iadd.20 or .Iaddend.21 wherein each of the said n×

m arrays respectively contains data at variance with the data of the other arrays, and said system further includes means for cyclically reading out in a predetermined series the data from said arrays so as to create the illusion of a continuously varying image. .[.24. A computer graphics system for displaying in an n×

m array of picture elements a magnified image of data contained in a zoomed portion of an N×

M memory array, comprising;

raster memory means including a data storage array having N rows and M columns of data storage sites;

means for providing an origin address signal for designating the origin site of an n/Z×

m/Z Array of storage sites in said raster memory means where Z is an integer, n/Z is an integer equal to or less than N, and m/Z is an integer equal to or less than M;

clock generating means for generating first, second and third clock signals, said first clock signal including m signal pulses for each signal pulse of said second clock signal, and said second clock signal including n signal pulses for each signal pulse of said third clock signal;

means for generating a zoom signal having a zoom factor of Z;

means responsive to said origin address signal, said first, second and third clock signals, and said zoom signal and operative to start at the origin site of said n/Z×

m/Z array and read out data from m/Z storage sites in each row thereof, the data contained in each site in each row being read out Z consecutive times before the data contained in the next adjacent site is read out, and the data read out of each row being repeated Z consecutive times before data is read out from the next row;

raster means for developing a raster scan signal from the data read out; and

display means responsive to said raster scan signal and operative to display an image corresponding to the data contained in said n/Z×

m/Z

16. said second n×

m array..]. 20. A computer graphics display system .[.as recited in claim 19.]. .Iadd.for displaying in raster fashion an image comprised of an n×

m array of picture elements, comprising;

raster memory means including a data storage array having N rows and M columns of data storage sites;

means for providing a selectable first origin address signal for designating the origin site of a first n×

m array of storage sites in said raster memory means, where n is an integer less than N and m is an integer less than M;

clock generating means for generating first, second and third clock signals, said first clock signal including Zm signal pulses for each signal pulse of said second clock signal, and said second clock signal including Zn signal pulses for each signal pulse of said third clock signal, where Z is any positive integer;

means responsive to said first origin address signal and said first, second and third clock signals and operative to start at the origin site of said first n×

m array and read out data from m storage sites in each of the n rows of said first n×

m array;

raster means for developing a raster scan signal from the data read out of said first n×

m array;

display means responsive to said raster scan signal and operative to display an image corresponding to the data contained in said first n×

m array;

means for providing a second origin address signal for designating the origin site of a second n×

m array of storage sites in said raster memory means;

means responsive to said second origin address signal and said first, second and third clock signals and operative to start at the origin site of said second n×

m array and read out data from m storage sites in each of the n rows of said second n×

m array;

wherein said raster means also develops another raster scan signal from the data read out of said second n×

m array and said display means also responds to said other raster scan signal to display the data contained in said second n×

m array; and

.Iaddend.wherein the data in said second n×

m array is read out and displayed at a time subsequent to the reading out and display of the data in said first n×

m array and means are provided for synchronizing the change in display with said third clock signal so that no displayed image includes data from both said first

21. means to create the illusion of a panning of said data storage array. 26. A computer graphics display system comprising:

raster memory means including a data storage array having N rows and M columns of data storage sites;

first means for providing a first origin address signal for designating the origin site of a first r×

m array of storage sites in said raster memory means;

second means for providing a second origin address signal for designating the origin site of a second s×

m array of storage sites in said raster memory means, where n is an integer equal to or less than N, m is an integer equal to or less than M, and r and s are integers selected to satisfy the equation r×

s=n;

clock generating means for generating first, second and third raster clock signals, said first raster clock signal including m signal pulses for each signal pulse of said second raster clock signal, and said second clock signal including n signal pulses for each signal pulse of said third clock signal;

means responsive to said first origin address signal, said second origin address signal and said first, second and third raster clock signals and operative to start at the origin site of said first array and to read out data from m storage sites in each of the r rows thereof and then start at the origin site of said second array and read out data from m storage sites in each of the s rows thereof;

raster means for developing a raster scan signal from the data read out from said first and second arrays; and

display means responsive to said raster scan signal and operative to display a split image containing the data from both said first array and

22. said second array. 27. A computer graphics display system comprising:

raster memory means including a data storage array having N rows and M columns of data storage sites;

first means for providing a first origin address signal for designating the origin site of a first n×

u array of storage sites in said raster memory means;

second means for providing a second origin address signal for designating the origin site of a second n×

v array of storage sites in said raster memory means, where n is an integer equal to or less than N, m is an integer equal to or less than M, and u and v are integers selected to satisfy the equation u+v=m;

clock generating means for generating first, second and third raster clock signals, said first raster clock signal including m signal pulses for each signal pulse of said second raster clock signal, and said second clock signal including n signal pulses for each signal pulse of said third clock signal;

means responsive to said first origin address signal, said second origin address signal and said first, second and third raster clock signals and operative to start at the origin site of said first array and read out data from u storage sites in the first row of said first array and then read out data from v storage sites in the first row of said second array followed by a series of similar split readouts of data from the next n-l rows of said first and second arrays;

raster means for developing a raster scan signal from the data read out from said first and second arrays; and

display means responsive to said raster scan signal and operative to display a split image containing the data from both said first array and

24. contained in said data storage array. 29. A computer graphics display system .[.as recited in claim 24 and further including.]. .Iadd.for displaying in an n×

m array of picture elements a magnified image of data contained in a zoomed portion of an N×

M memory array, comprising;

raster memory means including a data storage array having N rows and M columns of data storage sites;

means for providing an origin address signal for designating the origin site of an n/Z×

m/Z array of storage sites in said raster memory means where Z is an integer, n/Z is an integer equal to or less than N, and m/Z is an integer equal to or less than M;

clock generating means for generating first, second and third clock signals, said first clock signal including m signal pulses for each signal pulse of said second clock signal, and said second clock signal including n signal pulses for each signal pulse of said third clock signal;

means for generating a zoom signal having a zoom factor of Z;

means responsive to said origin address signal, said first, second and third clock signals, and said zoom signal and operative to start at the origin site of said n/Z×

m/Z array and read out data from m/Z storage sites in each row thereof, the data contained in each site in each row being read out Z consecutive times before the data contained in the next adjacent site is read out, and the data read out of each row being repeated Z consecutive times before data is read out from the next row;

raster means for developing a raster scan signal from the data read out;

display means responsive to said raster scan signal and operative to display an image corresponding to the data contained in said n/Z×

m/Z array; and

.Iaddend.means for selectively inhibiting the readout of data from each storage site for one or more of the Z consecutive readout operations, and for inhibiting the corresponding repeat readout of each row of data whereby a zoomed display of a plurality of adjacent storage sites containing data will be displayed as an array of spaced apart dots rather than as a solid area so as to provide a visually perceptible

17. n×

m array and said second n×

m array. 21. A computer grahics display system as recited in claim 20 and further comprising;

means for providing a series of other origin address signals identifying other n×

m arrays of storage sites located between said first and second n×

m arrays;

means responsive to each of said origin address signals and said first, second and third clock signals and operative to sequentially start at the origin site of each of said series of address signals and read out data from m storage sides in each of the n rows of each such array; and

means for generating a pan clock signal that is a multiple of said third clock signal for synchronizing the change in read out from one n×

m array to the other so as to create in the resulting display an illusion of smooth panning from said first n×

m array through said other

20. array..]. 25. A computer grahics display system .[.as recited in claim 24.]. .Iadd.for displaying in an n×

m array of picture elements a magnified image of data contained in a zoomed portion of an N×

M memory array, comprising;

raster memory means including a data storage array having N rows and M columns of data storage sites;

means for providing an origin address signal for designating the origin site of an n/Z×

m/Z array of storage sites in said raster memory means where Z is an integer, n/Z is an integer equal to or less than N, and m/Z is an integer equal to or less than M;

clock generating means for generating first, second and third clock signals, said first clock signal including m signal pulses for each signal pulse of said second clock signal, and said second clock signal including n signal pulses for each signal pulse of said third clock signal;

means for generating a zoom signal having a zoom factor of Z;

means responsive to said origin address signal, said first, second and third clock signals, and said zoom signal and operative to start at the origin site of said n/Z×

m/Z array and read out data from m/Z storage sites in each row thereof, the data contained in each site in each row being read out Z consecutive times before the data contained in the next adjacent site is read out, and the data read out of each row being repeated Z consecutive times before data is read out from the next row;

raster means for developing a raster scan signal from the data read out;

display means responsive to said raster scan signal and operative to display an image corresponding to the data contained in said n/Z×

m/Z array; and

.Iaddend.wherein said means for providing an origin address signal is synchronized with said third clock signal and is capable of sequentially providing other origin address signals in synchronism with said third clock signal so as to cause the display made by said display

25. separation of adjacent bits of data. 30. A computer graphics display system for use in association with a host computer to provide a visual display of graphics information contained therein, comprising:

a data bus;

an address bus;

display means for developing a visible image corresponding to video signals input thereto;

channel adapter means for providing an interface for communicating information including bits of graphics data between the host computer and said data bus and said address bus;

system control means communicatively coupled to said data bus and said address bus and operative to generate first and second control signals;

raster memory means including an array of N rows and M columns of storage sites each capable of storing a bit of graphics data corresponding to a picture element of a graphics image to be formed by said display means;

raster memory control means communicatively coupled to said address bus, said data bus, said raster memory means and said system control means, said raster memory control means being responsive to said first control signal and operative to cause bits of graphics data input from the host computer to be stored in said raster memory means, said raster memory control means including means for inputting data into selected ones of said storage sites and for causing such data input to sites presently occupied by other data to be logically exclusive ORed; and

video control means communicatively coupled to said address bus, said data bus, said raster memory means, said display means, and said system control means, said video control means being responsive to said second control signal and operative to read out in raster fashion data stored in said raster memory means and to use such data to generate a video signal for

26. input to said display means. 31. A computer graphics display system for use in association with a host computer to provide a visual display of graphics information contained therein, comprising:

a data bus;

an address bus;

display means for developing a visible image corresponding to video signals input thereto;

channel adapter means for providing an interface for communicating information including bits of graphics data between the host computer and said data bus and said address bus;

system control means communicatively coupled to said data bus and said address bus and operative to generate first and second control signals;

raster memory means including an array of N rows and M columns of storage sites each capable of storing a bit of graphics data corresponding to a picture element of a graphics image to be formed by said display means;

raster memory control means communicatively coupled to said address bus, said data bus, said raster memory means and said system control means, said raster memory control means being responsive to said first control signal and operative to cause bits of graphics data input from the host computer to be stored in said raster memory means, said raster memory control means including skip pattern control means for periodically inhibiting a storage operation in a predetermined manner so as to prevent certain bits of the data from being stored in said raster memory means, said skip pattern control means including a skip pattern memory for storing a plurality of predetermined skip pattern commands, and logic means controlled by said system control means and operative to select one of said skip pattern commands and to generate a first signal in accordance therewith for periodically inhibiting said storage operation, said skip pattern control means further including modulo arithmetic logic means for generating a second signal for periodically inhibiting said storage operation; and

video control means communicatively coupled to said address bus, said data bus, said raster memory means, said display means, and said system control means, said video control means being responsive to said second control signal and operative to read out in raster fashion data stored in said raster memory means and to use such data to generate a video signal for input to said display means. .[.32. A computer graphics display system comprising raster memory means including an array of N rows and M columns of storage sites, means for generating a control signal, means responsive to said control signal and operative to read out in raster fashion data stored in any selected block of n rows and m columns of said storage sites, where n is an integer less than N, and M is an integer less than M, and to use such data to generate a raster scan signal from the data read out of said selected block, and display means responsive to said raster scan signal and operative to display an image corresponding to the data

27. contained in said selected block..]. .Iadd.33. An apparatus for generating a graphics display having the illusion of smooth panning across an image represented by a plurality of discrete picture elements, said image being larger than that which can be displayed at one time on a video display device, comprising:

a memory device;

means for entering in the storage sites of said memory device a set of digital data corresponding to the discrete picture elements of said image, selected subsets of said digital data being readable from said memory to produce a corresponding raster signal displayable by said video display device;

specifying means for specifying a first particular portion of said memory storage sites, said first particular portion containing a first subset of digital data corresponding to a first part of said image, said first part being displayable at one time on said video display device;

first selecting means for selecting a second particular portion of said memory storage sites, said second particular portion containing a second subset of digital data corresponding to a different, second part of said image, said second part also being displayable at one time on said video display device;

second selecting means for selecting a plurality of other portions of said memory storage sites, said other portions each containing a respective other subset of digital data corresponding to other parts of said image, said other parts being situated at contiguous spaced intervals in said image between said first part and said second part, each of said other parts also being displayable at one time on said video display device;

read-out means for reading out digital data in raster fashion from said memory device and for providing said corresponding raster signal in response thereto;

control means, cooperating with said read-out means, said specifying, means and said first and second selecting means, for directing said read-out means initially to read out in raster fashion said first subset of digital data contained in said first portion to develop a first raster signal, then sequentially to read out the other subsets of digital data in each of said other portions to develop a series of other raster signals, then to read out in raster fashion the second subset of digital data contained in said second portion to develop a second raster signal; and

display production means, connected to said read-out means, for using said first raster signal, said other raster signals, and said second raster signal in the order that they are developed to produce on said video display device a raster display of the data contained in the various selected portions such that the produced display creates the illusion of smooth panning across said image from said first part to said second part.

28. Iaddend. .Iadd.34. An apparatus according to claim 33 wherein said control means synchronizes the read-out of each subset of digital data with a new frame of said video display device, and wherein said first part, each other part and said second part of said image are sequentially spaced from each other by a very few discrete picture elements. .Iaddend.

29. Iadd.35. An apparatus for generating a graphics display comprised of n rows and m columns of discrete picture elements, comprising:

storage means for storing a set of picture element data in a memory device having storage sites corresponding to an N×

M array;

selecting means for selecting a particular portion of the storage sites corresponding to an m/Z×

n/Z array where n/Z is equal to or less than N, where m/Z is equal to or less than M, and were Z is an integer;

read-out means, cooperating with said storage means and said selecting means, for reading out in raster fashion the data contained in each row of said particular portion and for supplying said read-out data as a raster signal, the data in each storage site being supplied Z times, and the data read out of each row being repeated Z times before data from the next row is read out;

display utilization means, connected to said read-out means, for using said raster signal in a video display device to produce a "zoomed" display of the data contained in said particular portion, said display containing a Z×

Z array of picture elements corresponding to each storage site in said portion of said N×

M array; and

inhibit means, cooperating with said read-out means and said display utilization means, for selectively inhibiting the supply of data from each storage site for one or more of the Z consecutive supply times, and for inhibiting the corresponding ones of the repeat readouts of each row of data such that a zoomed display of a plurality of adjacent storage sites containing data will be displayed as an array of spaced apart dots rather than as a solid area. .Iaddend. .Iadd. 36. An apparatus for generating a graphics display having a background grid, comprising;

storing means for storing a set of data in a memory device, said stored data respectively representing the displayable picture elements of an image;

read-out means, cooperating with said storing means, for sequentially reading out in raster fashion the data contained in said memory device to develop a raster data signal;

grid signal generation means for simultaneously generating a grid signal including a train of pulses which occur in a series of regularly timed intervals; and

mixing means, connected to said read-out means and to said grid signal generation means, for mixing said raster data signal and said grid signal to develop a composite raster display signal in which read out datum components of said raster signal are combined with simultaneously occurring pulses of said grid signal, said composite raster display signal being utilizable by a raster-type video display device to produce a graphics display including the data read out of said memory device and a background grid including vertical and horizontal grid lines of data superimposed on the displayed picture element data. .Iaddend..Iadd. 37. An apparatus for generating a graphics display as recited in claim 36 wherein said grid signal generation means includes modification means for modifying certain ones of said pulses so as to cause said grid to appear to contain major and minor grid lines of different intensity. .Iaddend. .Iadd. 38. An apparatus for implementing smooth panning in a computer graphics display system of the type having a memory storing digital data corresponding to picture elements of an image that is larger than can be displayed at one time, and in which a subset of said stored digital data is read out from said memory and supplied to a video display device in raster fashion to produce on said device a display of the portion of said image represented by said data subset, each such data subset being specified by a corresponding origin address within said memory, comprising;

pan clock means for generating a pan clock signal that is synchronized with the frame rate of said video display device;

first means for specifying a first data subset representing that first position of said image at which panning is to begin;

second means for specifying a second data subset representing the second portion of said image at which is panning is to terminate;

third means for specifying data subsets representing closely, sequentially contiguous portions of said image intermediate said first and second portions; and

read-out means, cooperating with said pan clock means and with said first, second and third means, for sequentially reading out from said memory said first, said group of intermediate, and said second data subsets in raster fashion for supply to said video display device to produce corresponding sequential displays of the portions of said image represented thereby, each such sequential readout being synchronized with said pan clock signal, whereby the resultant display has the illusion of smooth panning in which each successive video frame synchronized display represents a portion of said image that is closely contiguous to the preceeding display. .Iaddend. .Iadd. 39. An apparatus according to claim 38 wherein said first, second and third means each is configured to specify the respective said first, second, and intermediate data sets by an associated data set origin address. .Iaddend..Iadd. 40. An apparatus according to claim 39 wherein each successive intermediate origin address differs from the preceding intermediate origin address by a very few picture element distances. .Iaddend. .Iadd.41. An apparatus according to claim 39 wherein said third means for specifying comprises;

spacing logic circuitry for determining a value corresponding to the desired spacing between said sequentially contiguous portions of said image; and

comparing logic circuitry for determinng if the portion of said image that is currently being displayed on said video device is the same as said second portion, and if not, for arithmetically combining said desired spacing value with the origin address of the data subset representing the currently displayed portion of said image to obtain the new origin address corresponding to the next sequential portion of said image. .Iaddend. .Iadd. 42. An apparatus for providing a "zoom" magnification effect in a computer graphics display system of the type wherein digital data representing each picture element of an image is stored in a memory and wherein a subset of said digital data is read out from said memory and supplied to a video display device in raster fashion to produce a display of a corresponding portion of said image, comprising;

means for supplying to said video display device, during read out of the data for each raster scan line of said video display device, each datum a plurality of p times and for supplying no datum for (Z-p) times, where Z is an integer equal to the desired "zoom" magnification scale;

means for repeating said readout of the data for each raster scan line a multiple of q raster scan line times and for supplying no datum for (Z-q) raster scan line times before reading out the data for the next raster scan line;

whereby a "zoom" magnified display is produced in which each stored picture datum in said subset is displayed on said video display device as a p×

q array of contiguous picture elements that is spaced from the adjacent displayed array corresponding to a contiguous stored datum in said subset. .Iaddend. .Iadd. 43. A panning raster scan graphic display apparatus comprising;

memory means for storing data representative of the elements of an image larger than that which can be simultaneously displayed by said apparatus;

access means, cooperating with said memory means, for accessing from said memory means in accordance with a raster control signal the subset of said data representing elements of a specified subimage of said image, and for forming a raster scan signal representation of said subimage;

display means, connect to said access means and receiving said raster scan signal, for visually portraying said specified subimage;

control means for specifying a first subimage of said image for current display and a second subimage of said image for eventual display; and

spacing means, cooperating with said access means and said control means, for determining a sequence of subimages of said image, said sequence starting with said first subimage and ending with said second subimage, and for sequentially specifying to said access means, in coordination with said raster control signal, each of said subimages in said sequence, thereby panning from said first to second subimage on said display means.

30. Iaddend. .Iadd.44. An apparatus according to claim 43 wherein said spacing means determines consecutive subimages in said sequence to be substantially overlapping so as to provide a smooth panning. .Iaddend. .Iadd.45. A zoomable raster scan display apparatus comprising:

memory means for data storage of an M row by N column picture element `image` array representing an image to be zoomed;

zoom means for accessing picture elements from said memory means and for generating thereform a raster scan signal representing a `zoom` array of ZM rows by ZN columns of picture elements, where Z is an integer zoom value, said `zoom` array composed of Z by Z blocks of like picture elements, each block corresponding to a single picture element in said `image` array;

display means, receiving said raster scan signal, for displaying a zoomed image corresponding to said `zoom` array of picture elements; and

blanking means, cooperating with said zoom means, for processing said raster scan signal before utilization by said display means to selectively mask a specifiable subset of picture elements in each said Z×

Z block. .Iaddend.