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Selectively Increasing Character Box Size

IP.com Disclosure Number: IPCOM000051255D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

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A display character box size is enlarged and ROS costs are reduced through the use of combinational logic.

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Selectively Increasing Character Box Size

A display character box size is enlarged and ROS costs are reduced through the use of combinational logic.

A read-only store (ROS) module used as a character generator can accommodate a binary multiple of characters, each consisting of a binary multiple of scan lines. For example, an 8K X 8 ROS module is capable of handling 512 characters for 8 x 16-bit or - dot character boxes. When slightly larger character boxes are required, such as 8 x 18 or 8 x 19, using additional ROS modules is not always an acceptable solution. This is because the difference in cost between 1K X 8, 2K X 8, 4K X 8, and 8K X 8 ROS modules is not linear.

A ROS module is used to transform a set of inputs into outputs. Stored inside the module is the output information for all possible combinations of inputs. If the outputs are identical for the majority of the input combinations, then a more cost- effective solution for increasing character box sizes is to use combinational logic to transform only those sets of inputs which produce unique outputs.

Consider an 8 x 18-dot box. A determination is first made as to the number of scan lines in the character box that exceeds the ROS capacity. In this case there are two. If the bottom two scan lines are chosen, it can be seen that except for characters with diacritics, underscores, descenders, etc., the information contained in these two lines is zero for most characters. Thereafter, the address of the chara...