Re: Switching to Double Hi-Res (DHGR) within a program

["Charlie" <charlieDOTd@verEYEzon.net>]

"vectorthom" <greg.rossiter@gmail.com> wrote in message 
ebe3e48f-7c50-4a08-a2dc-5c9533db1d89@j18g2000yqd.googlegroups.com">news:ebe3e48f-7c50-4a08-a2dc-5c9533db1d89@j18g2000yqd.googlegroups.com...
> Hello all,
>
> I'm trying to learn how to use Double Hi-Res graphics on the Apple
> II.  I've recently acquired an Apple IIe to replace one my family 
> sold
> years ago and am reliving my '80s childhood through old floppy 
> disks
> that I still have on-hand.  I don't remember even knowing about 
> double
> hi-res graphics back then, but I'd like to start experimenting 
> with it
> now.  I have Broderbund's Dazzledraw (a DHGR program) and a bunch 
> of
> homemade drawings saved to disk.  I have a Rev. B Apple IIe and an 
> 80
> col/64k expansion card, so I believe I have the machine capability 
> to
> display DHGR.  At the prompt, I know that entering "PR#3" will 
> switch
> me to 80 column mode, where all the text gets visibly thinner.  Is
> this essentially DHGR mode or is there more to it than that?
>
> My main question however is this:  how do I switch to DHGR mode 
> once
> I'm within a program?  As said, I can switch to 80 column mode 
> when
> I'm at the prompt, but when I reboot to start loading Dazzledraw 
> for
> example, it hops back to 40 column mode.  I don't see a way to 
> switch
> back from within the program.  I'm curious to know if I'm viewing 
> my
> created images at their best or if they would look better in 80 
> column
> mode. Is there a relatively easy way to toggle back and forth 
> between
> video modes?
>
> Thanks,
> Greg R

To turn on Double Hi-Res (DHR) from an Applesoft BASIC program:

10 X = PEEK(49239) : REM TURNS ON HI-RES
20 X = PEEK(49232) : REM TURNS ON GRAPHICS
30 X = PEEK(49246) : REM TURNS ON DOUBLE HI-RES
40 X = PEEK(49235) : REM TURNS ON MIXED MODE (OPTIONAL)
50 POKE 49165,0 : REM TURNS ON 80 COLUMN MODE

This is pretty much from Apple II Tech note #3.

The locations that you peek or poke are called softswitches and 
there are ones to turn on/off the different video modes as well as 
other stuff.  You should get a list of all the softswitches.
There's one at:

http://www.textfiles.com/apple/

Look for appswitc.app.

Charlie