Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!unmvax!pprg.unm.edu!hc!lll-winken!lll-lcc!pyramid!athertn!paul
From: paul@athertn.Atherton.COM (Paul Sander)
Newsgroups: comp.sys.apple
Subject: Re: Page flipping
Summary: Can be done right on a II+, but...
Message-ID: <371@athertn.Atherton.COM>
Date: 15 Mar 89 19:12:28 GMT
References: <8903141654.aa28044@SMOKE.BRL.MIL>
Organization: Atherton Technology, Sunnyvale, CA
Lines: 18

>         Page flipping helps, but on the ][+ it can cause the undesirable split
> effect when you flip while the raster beam is in the vertical middle of your
> character.  Only on the ][e (and presumable ][c, ][gs) can you do page-
> flipping right, since it provides you with information on when the electron
> gun is doing a vertical blank (going back to start at the top again).

Just before the IIe was released, Don Lancaster published a book entitled 
"Enhancing Your Apple II" which addresses this issue.  He also gave a talk 
at the West Coast Computer Faire that year that discussed a better method.

Both methods required making reversable changes to the motherboard (the first
method, I believe, required adding only one wire).  Of course, at this late
date, I don't think anyone is worried about voiding their warrantees if they
wish to try this.
-- 
Paul Sander        (408) 734-9822       | Do YOU get nervous when a
paul@Atherton.COM                       | sys{op,adm,prg,engr} says
{decwrl,sun,hplabs!hpda}!athertn!paul   | "oops..." ?