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GRAB Locks The Computer When Loaded Under A M |
The information in this document applies to:
WordPerfect® 5.1 for DOS
Problem
Symptoms: A customer was using a menu software program that allowed the customer to go to a DOS prompt (similar to what Windows does). After going to DOS, the customer loaded GRAB.COM and then went into WP. GRAB worked fine in WP, but when the customer exited back to the menu software, the machine locked. Solutions: GRAB was not designed to be run underneath another software program. The manual states that GRAB must be run from DOS and that it cannot be executed while shelled to a DOS prompt. The customer should load GRAB before starting the menu software. How/Why: GRAB continually monitors keyboard strokes waiting for its sequence to be pressed. When a key is pressed, an Interrupt code occurs in the machine. This Interrupt calls a chain of routines that handles the keystroke. When GRAB is executed, it places itself in a position to be one of the first applications to monitor a keystroke. After GRAB has analyzed a keystroke, it passes the keystroke on to the next application in line. The keystroke is passed along and will ultimately be received by the front-running application. When a user exits back to a menu program, the memory allocated to GRAB becomes invalid, GRAB is no longer able to pass keystrokes along, and the front-running application has no way to receive keystrokes. |
Answer:
Details:
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