Browse Prior Art Database

Pseudo Real-Time Frame Grabbing for IBM PC

IP.com Disclosure Number: IPCOM000099150D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 1 page(s) / 48K

Publishing Venue

IBM

Related People

Sack, T: AUTHOR

Abstract

It is important for some processes to integrate cameras for real-time imaging functions with This can be approached on PC computers by using technology.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

Pseudo Real-Time Frame Grabbing for IBM PC

       It is important for some processes to integrate cameras
for real-time imaging functions with  This can be approached on PC
computers by using technology.

      It is desirable that frame grabbers acquire images at real-
time rate of about 30 frames/second.  However, cannot be grabbed at
any time.  They must be grabbed the instant after vertical retrace of
the image.  This difficulty as timing is critical.  It becomes more
when the frame grabber is a hardware expansion in the IBM PC and the
PC software is to control the  The timing requirements cause
difficulty in trying incorporate frame-grabbing code into user
software.  The the user could hope for would be to access discrete at
predetermined stages within the program and at less than the
real-time rate.

      Pseudo real-time frame grabbing can be obtained by use of the
fact that the 8253 timer chip on the IBM motherboard issues an
interrupt once every 0.055 second 18.2 interrupts/second) to notify
the PC that it has down and that the PC clock should be incremented.
interrupt can be used by software to obtain relatively speed frame
grabbing.

      The interrupt referred to above is serviced by INT8  This
interrupt is special because it updates clock and issues a call to
INT ICH.  The vector for INT normally points to a dummy return (IRET)
(it does  If the vector is changed to point to a useful then the PC
can be made to automatically perform f...