Display memory with write inhibit signal for transparent foreground pixel codes

Claim 1

A method for writing patterns into a display memory coupled to a display device by means of which the patterns are to be displayed, each of the patterns being stored in the from of pixel codes each indicating the brightness of color of a corresponding pixel of the display device when that pattern is displayed, each of said pixel codes indicating whether its corresponding pixel is to be considered transparent, said method comprising the steps of: (a) using a processor to select a background pattern, and writing the background pattern into said display memory; (b) using the processor to select a foreground pattern and to select a location of the display memory whereat the selected foreground pattern is to be displayed, some of the pixels of said foreground pattern having transparent pixel codes; (c) using the processor to obtain a foreground pattern data word of the selected foreground pattern, said foreground pattern data word including at least one of said pixel codes; (d) using the processor to transmit at least one pixel code representative of the information in the foreground pattern data word, a write signal, and an address representing the selected location, from the processor to the display memory, said transmitting being performed after the background pattern has been written into the display memory; (e) using a sensing circuit external to the processor to effectuate sensing each transmitted pixel code, without reference to the background pattern, to determine if its corresponding pixel is to be considered transparent; (f) for each foreground pixel code transmitted, (i) enabling said write signal to cause writing of that pixel code into the addressed location of the display memory in response to said sensing circuit on the condition that said sensing indicates that the pixel corresponding to that pixel code is not to be considered transparent, or (ii) inhibiting said write signal to prevent writing of that pixel code into the addressed location of the display memory in response to said sensing circuit on the condition that said sensing indicates that the pixel corresponding to that pixel code is to be considered transparent and therefore is not to be written into said display memory system.

Claim 2

A method for writing patterns into a display memory coupled to a display device by means of which the patterns are to be displayed, each of the patterns being stored in the from of pixel codes each indicating the brightness of color of a corresponding pixel of the display device when that pattern is displayed, each of said pixel codes indicating whether its corresponding pixel is to be considered transparent, said method comprising the steps of: (a) using a processor to select a background pattern, and writing the background pattern into said display memory; (b) using the processor to select a foreground pattern and to select a location of the display memory whereat the selected foreground pattern is to be displayed, some of the pixels of said foreground pattern having transparent pixel codes; (c) using the processor to obtain a foreground pattern data word of the selected foreground pattern, said foreground pattern data word including at least one of said pixel codes; (d) using the processor to transmit at least one pixel code representative of the information in the foreground pattern data word, a write signal, and an address representing the selected location, from the processor to the display memory, said transmitting being performed after the background pattern has been written into the display memory; (e) using a sensing circuit external to the processor to effectuate sensing each transmitted pixel code, without reference to the background pattern, to determine if its corresponding pixel is to be considered transparent; (f) for each foreground pixel code transmitted, (i) enabling said write signal to cause writing of that pixel code into the addressed location of the display memory in response to said sensing circuit on the condition that said sensing indicates that the pixel corresponding to that pixel code is not to be considered transparent, or (ii) inhibiting said write signal to prevent writing of that pixel code into the addressed location of the display memory in response to said sensing circuit on the condition that said sensing indicates that the pixel corresponding to that pixel code is to be considered transparent and therefore is not to be written into said display memory system.

Claim 11

An apparatus for writing patterns into a display memory coupled to a display device, said apparatus comprising in combination: a processor for performing data proessing operations; storage means responsive to said processor for storing a plurality of said patterns, each of said patterns being stored as information including pixel codes corresponding to the brightness or color of each pixel of said display device when that pattern is displayed by the display device, said pixel codes also indicating whether each pixel is to be considered transparent; means in said processor for selecting a background pattern and writing that background pattern into said display memory; means in said processor for selecting (1) a foreground pattern to be displayed and (2) a location of said display device whereat the selected foreground pattern is to be displayed, some of the pixels of said foreground pattern having transparent pixels codes; means in said processor for fetching a foreground pattern data word of the selected foreground pattern from said storage means, said foreground pattern data word including at least one pixel code; means responsive to said fetching means for transmitting at least one pixel code representative of the information in the fetched foreground pattern data word, a write signal and an address representing the selected display location to said display memory after the background pattern has been written into said display memory; sensing means external to said processor and coupled to said display memory for receiving said transmitted pixel code of the fetched foreground pattern data word and sensing each transmitted pixel code, without reference to the background pattern, to determine if its corresponding pixel is transparent; write circuit means responsive to said sensing means for (1) enabling said write signal to effect writing of each of said transmitted pixel codes into a presently addressed location of said display memory on the condition that said sensing means determines that the pixel corresponding to that pixel code is not to be considered transparent; and (2) inhibiting said write signal from effecting writing of each of said transmitted pixel codes into the presently addressed location of said display memory on the condition that said sensing means determines that the pixel corresponding to that pixel code is to be considered transparent.

Claim 12

An apparatus for writing patterns into a display memory coupled to a display device, said apparatus comprising in combination: a processor for performing data proessing operations; storage means responsive to said processor for storing a plurality of said patterns, each of said patterns being stored as information including pixel codes corresponding to the brightness or color of each pixel of said display device when that pattern is displayed by the display device, said pixel codes also indicating whether each pixel is to be considered transparent; means in said processor for selecting a background pattern and writing that background pattern into said display memory; means in said processor for selecting (1) a foreground pattern to be displayed and (2) a location of said display device whereat the selected foreground pattern is to be displayed, some of the pixels of said foreground pattern having transparent pixels codes; means in said processor for fetching a foreground pattern data word of the selected foreground pattern from said storage means, said foreground pattern data word including at least one pixel code; means responsive to said fetching means for transmitting at least one pixel code representative of the information in the fetched foreground pattern data word, a write signal and an address representing the selected display location to said display memory after the background pattern has been written into said display memory; sensing means external to said processor and coupled to said display memory for receiving said transmitted pixel code of the fetched foreground pattern data word and sensing each transmitted pixel code, without reference to the background pattern, to determine if its corresponding pixel is transparent; write circuit means responsive to said sensing means for (1) enabling said write signal to effect writing of each of said transmitted pixel codes into a presently addressed location of said display memory on the condition that said sensing means determines that the pixel corresponding to that pixel code is not to be considered transparent; and (2) inhibiting said write signal from effecting writing of each of said transmitted pixel codes into the presently addressed location of said display memory on the condition that said sensing means determines that the pixel corresponding to that pixel code is to be considered transparent.