Re: DHGR Video Riddle Solved!!!

[david@uow.edu.au (David Wilson)]

"Arkain" <rwking@no.usa.spam.net> writes:
>Phoenyx <quazar@dcnet2000.com> wrote in message

>$C00D ->Turn On 80 Columns
>$C050 ->Turn Graphics On
>$C057 ->Make It Hires
>$C05E ->Turn off AN3

These are all documented on pages 95-96 of the Apple IIc Technical Reference
Manual. The only proviso is that to access the DHiRes switch (AN3) at $C05E/F
the IOUDis switch must be on (IOUDis On = write to $C07E, IOUDis Off = write
to $C07F, IOUDis status = read $C07E bit 7 (1 = off) [it should have been
called IOUEnable and on/off swapped in my opinion].

The IOUDis switch controls access to locations $C058..C05F.

On page 97 there is a table listing all the softswitch combinations required
to display all possible modes (all 15 of them). As an example they give the
following code to switch into mixed 80 column and double-high-resolution mode
display page 1:

	STA	$C00D	; turns on 80Col, firmware turns on 80Store
	LDA	$C054	; turns off Page2 (STA would have worked as well)
	STA	$C050	; turns off text (turns on graphics)
	STA	$C053	; turns on MIXED (works now that TEXT is off)
	STA	$C057	; Turns on HIRES (ditto)
	STA	$C07E	; Makes sure IOUDis is on so that DHiRes access ok
	LDA	$C05E	; turns on DHiRes (works now that IOUDis is on)
--
David Wilson  School of IT & CS, Uni of Wollongong, Australia