Microtel Limited

Oliver T Yu

A technique is disclosed for use in an electronic raster-scan display system, for generating characters of variable size using a stroke-vector technique. An incoming data signal defines the type of character to be displayed, the horizontal X and vertical Y character field dimensions, the character drawing point, and any character rotation or reflection. Using that part of the data signal that defines the character type as a memory address, a character microprogram is retrieved containing a stroke-vector character mask and a stroke resolution factor representing the number x of horizontal stroke-vectors in a straight line and the number y of vertical stroke-vectors in a straight line that are used by said character mask to represent said character within a normalized character field. To scale the size of the stroke-vectors the horizontal length stroke-vector attribute DX-LENGTH is forming by taking the quotient X/x, and the vertical length stroke-vector attribute DY-LENGTH is forming by taking the quotient Y/y. Then the DX-LENGTH attribute and the DY-LENGTH attribute are converted from the display screen coordinate system to a virtual screen coordinate system having a greater resolution than the physical screen coordinate system. One or both length attributes can be applied to each stroke-vector. At this point the character image having the proper size exists in the virtual screen coordinate system. To convert it back to the actual display screen coordinate system the size attributes DX-LENGTH and DY-LENGTH are divided down by the proper factor. Lastly a logical pel may be generated and added to the individual stroke-vectors before the connected stroke-vectors are projected onto the display screen at the character drawing point.

Technique for scaling characters in a stroke-vector display system

A novel stroke-vector character generator is disclosed for generating characters or the like in a raster-scan video display system. An external data signal defines the type of character to be displayed, the character field dimensions, the character drawing point, and any character rotation or reflection. Using that part of the data signal that defines the character type as a memory address, the character generator retrieves from memory a character microprogram containing a plurality of encoded binary valued stroke-drawing directives. These directives are instructions to a decoder how to generate all of the shape dependent attributes for a series of chain related stroke-vectors that define the overall shape of the character to be displayed. Once defined in the system, each stroke-vector is scaled so that the character cell size matches the character field dimensions defined by the external data signal. Lastly a logical pel may be generated and added to the individual stroke-vectors before the connected stroke-vectors are projected onto the display screen at the character drawing point.

Stroke-vector character generator

A novel method is disclosed for use in an electronic raster-scan display system, for generating characters using a stroke-vector technique. An incoming data signal defines the type of character to be displayed, the character field dimensions, the character drawing point, and any character rotation or reflection. Using that part of the data signal that defines the character type as a memory address, a character microprogram is retrieved containing a plurality of encoded binary valued stroke-drawing directives. These directives are instructions detailing how to generate all of the shape dependent attributes for a series of chain related stroke-vectors that define the overall shape of a character to be displayed. The encoded drawing directives are decoded and sequentially applied to a set of initial values that define an initial virtual stroke-vector, and thereby generating all of the character-shape dependent stroke attributes to for a series of chain related stroke-vectors that define a character shape. Once defined each stroke-vector is scaled so that the generated character cell size corresponds to the character field dimensions defined by the external data signal. Lastly a logical pel may be generated and added to the individual stroke-vectors before the connected stroke-vectors are projected onto the display screen at the character drawing point.

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Vancouver, Canada

Oliver T Yu