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Row Table Addressing Method for Smooth Scroll

IP.com Disclosure Number: IPCOM000034293D
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Iida, H: AUTHOR [+3]

Abstract

This article describes a method for an easy smooth scroll (S/S) control which uses a row table control method for the character display. In the case of a normal row table control method there is only one row table for the display but, in this method, there is an additional row table (sub-row table) for the S/S which is controlled by hardware in order to improve the performance from a programming point of view. (Image Omitted) Figs. 1, 2 and 3 show the S/S performance of this method. There are two row tables: one is a main row table used for the normal display screen, and the other is a sub-row table which has only one element and is used for a row disappearing from the screen during S/S. Fig. 1 shows the condition of two row tables during normal display and just before S/S.

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Row Table Addressing Method for Smooth Scroll

This article describes a method for an easy smooth scroll (S/S) control which uses a row table control method for the character display. In the case of a normal row table control method there is only one row table for the display but, in this method, there is an additional row table (sub-row table) for the S/S which is controlled by hardware in order to improve the performance from a programming point of view.

(Image Omitted)

Figs. 1, 2 and 3 show the S/S performance of this method. There are two row tables: one is a main row table used for the normal display screen, and the other is a sub-row table which has only one element and is used for a row disappearing from the screen during S/S. Fig. 1 shows the condition of two row tables during normal display and just before S/S. Both numbers of main row table elements and of rows displayed in a screen are n (elements/rows). The sub-row table is not addressed by a controller at this time. Fig. 2 shows the condition during S/S down (meaning displayed characters go down). When S/S starts, a row table element which directs the disappearing row ('I' in this example) is deleted from main row table and is copied to the sub row table, and a new row table element which will direct an appearing row ('X') is inserted in the main table. These operations are held during the first vertical blank. After that, the main row table becomes complete conditions/order which is the same one as a...