Path: utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!sdd.hp.com!ucsd!ucbvax!GRIN1.BITNET!THROOP
From: THROOP@GRIN1.BITNET ("Throop,Henry B")
Newsgroups: comp.sys.apple2
Subject: Re: Display Softswitches
Message-ID: <9010251449.AA28523@apple.com>
Date: 25 Oct 90 01:08:43 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 13

[stuff about VBL interrupts on IIc]

Keep in mind with all this confusion that the gs and the //e handle the VBL
register (at $c019) differently - on the //e, the high bit clear means VBL
blanking, and on the gs, it's the high bit set.  You can also, of course, set
VBL interrupts on the gs, but not on the //e.  The ][+ doesn't have a VBL
register, but with a one wire mod you can take the VBL signal and put it in
one of the pdl switch inputs.

--
Henry Throop
THROOP@GRIN1.BITNET
throoph@jacobs.cs.orst.edu