Browse Prior Art Database

Shadow Cursor Capability for Single-Cursor

IP.com Disclosure Number: IPCOM000042814D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Anderson, GD: AUTHOR [+2]

Abstract

This dual cursor method places a secondary or "shadow" cursor 10 n the on the scale line 12 of display 14. The shadow cursor 10 and the primary cursor 16 move in tandem in the horizontal direction.

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Shadow Cursor Capability for Single-Cursor

This dual cursor method places a secondary or "shadow" cursor 10 n the on the scale line 12 of display 14. The shadow cursor 10 and the primary cursor 16 move in tandem in the horizontal direction.

The primary cursor 16 can also be moved in the vertical direction. The shadow cursor 10 is an opaque box. This cursor disappears when a "character" is entered in or deleted from the scale line 12; this provides immediate visual feedback. The shadow cursor reappears when either of the horizontal cursor move keys is depressed. The shadow cursor 10 uses a character already in character generator 18 hardware (ROS (read-only store)) to simulate a shadow cursor. The primary cursor is displayed locally by hardware in display 14 responsive to the I/O address register 20 of the refresh buffer 22 (RAM (random- access memory)). This shadow cursor character 10 actually replaces a character in display screen refresh buffer 22. It is written into buffer 22 at the column position in 12 derived from a cursor register 24 in controller 26 which keeps track of the contents of register 20 and thus the position of 16. The writing of the character generator code for cursor 10 replaces the original or "underlying" character code at the location in buffer 22 corresponding to 10. However, controller 26 keeps a copy of line 12 whereby the underlying character (temporarily replaced by 10) is saved by controller 26 and later restored to buffer
22. Provid...