Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!uunet!unsvax!uns-helios!alfter
From: alfter@uns-helios.nevada.edu (SCOTT ALFTER)
Newsgroups: comp.sys.apple2
Subject: Display Softswitches
Message-ID: <2142@unsvax.NEVADA.EDU>
Date: 11 Oct 90 03:09:46 GMT
Sender: news@unsvax.NEVADA.EDU
Reply-To: alfter@uns-helios.uucp (SCOTT ALFTER)
Organization: Univ of Nevada System Computing Services - Las Vegas
Lines: 44

I've finally gotten around to looking up the display softswitches, for whoever
it was that asked.  This information is out of the _Apple_IIe_Technical_
_Reference_Manual_.

Switch    Description                           Address
--------- ------------------------------------- -------
TEXT      on: display text                      C051
          off: display graphics                 C050
          read TEXT switch                      C01A
MIXED     on: graphics w/4-line text window     C053
          off: graphics only                    C052
          read MIXED switch                     C01B
PAGE2     on: select text/graphics page 2       C055
          off: select text/graphics page 1      C054
          read PAGE2 switch                     C01C
HIRES     on: Hi-Res graphics                   C057
          off: Lo-Res graphics                  C056
          read HIRES switch                     C01D
80COL     on: 80-column text                    C00D
          off: 40-column text                   C00C
          read 80COL switch                     C01F
80STORE   on: write display info to aux. mem.   C001
          off: write display info to main mem.  C000
          read 80STORE switch                   C018
ALTCHAR   on: inverse lowercase & MouseText     C00F
          off: flashing text                    C00E
          read ALTCHAR switch                   C01E
AN3       on: double Hi-Res (also annunciator   C060
              3 output at the game I/O port)
          off: regular Hi-Res                   C05F
VBL       read vertical blanking                C019

To set a switch, store something to that address (POKE it from BASIC).  If you
want to read a switch, load from that address (PEEK it from BASIC); the switch
is set if the high bit is set.  Note that you can't read the setting of AN3.
Also, VBL doesn't indicate the setting of a switch, but indicates when the
video circuitry isn't tracing the picture.  For smoother graphics, only change
the screen contents when the high bit of VBL is clear.

-----------------------------------------------------------------------------
Scott Alfter                             _/_
                                        / v \ Apple II:
Internet: alfter@uns-helios.nevada.edu (    ( the power to be your best!
   GEnie: S.ALFTER                      \_^_/