VERTICAL BLANK VECTORS









From: visitor

Date: 07/30/89-09:23:17 AM Z



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From: visitor
Subject: VERTICAL BLANK VECTORS
Date: Sun Jul 30 09:23:17 1989


How do you set up a VBI?  Every time I try it comes out wrong.  thanx.
/s


** Answered by JOHN SUCHY (aa271) on Sat Jun 27 00:31:55 1987 **

        Since you have been having some
form of results--even bad ones--I'll
assume that you know about the Vector,
or "address of subroutine" associated
with the Verticle Blank Interrupt (VBI,
things that happen while the TV screen
can't see them).  In that case you are
probably forgetting to branch back to
the standard VBI routines at the end of
your code. A JuMP to the original 
address in the VBI vector should do it.
Let me know whether this helps.

                        Your Co-sysop
                        John E. Suchy
                        aa271
         Thanks for asking.





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