Re: Hopefully last dumb newbie question.

[Slick <PAYSlick_RCBD@hotmail.com>]

Mitchell Spector wrote:
> 
> In article CUTjefbla@bconnex.net (Jeff Blakeney) writes...
> 
> >On Thu, 04 Jun 1998 13:43:07 -0500, Slick <Slick_RCBD@hotmail.com>
> >wrote:
> >
> >>Now the question. What exactly does the Alternate Display Mode DA do? I
> >>think it has something to do with the secondary text screen (Address
> >>$800-C00 on earlier models), but am not sure. None of the books at my
> >>library have anything about it. I do know about the shadowing to banks
> >>$e0 and $e1, and have looked at assembly language programming on the
> >>IIGS. I just never had the money to buy ORCA or APW. I've used the Hyper
> >>C (ProDOS 8, and free) assembler to write programs.
> >
> >If I remember correctly, text page 2 doesn't get shadowed or the
> >softswitch for changing to text page 2 doesn't work or something like
> >that.  The Alternate Display CDA allows you to enable or disable
> >another shadowing routine, which is slower than the hardware
> >shadowing, but allows certain older 8 bit programs to use text page 2
> >so that they will work correctly.
> 
>     Another nice feature about the ROM 3 IIgs is there is hardware
> shadowing for text page 2 built-in. If you run a program that uses
> it (example: joystick calibration in Goonies) it will automatically
> activate, and it doesn't slow down the computer. In that sense the
> ROM 3 is more compatible with 8-bit software.
> 
> >If an 8 bit program crashes or doesn't run correctly, try enabling the
> >Alternate Display mode and try it again.  It just might work.
> 
>     Usually you'll see a screen filled entirely with the number "2".
> I'm not sure if this is a coincidence or Apple had it purposely used
> to give a hint to the user, instead of random garbage on the screen. :)
> 
> Mitchell Spector
> spec@vax2.concordia.ca
If it is automatic, why is the Alternate Display Mode DA still in the
CDA menu of a ROM 3? Also, my Pacman still had the screen filled with
2's when I brought the disk over to my old friend's house. When I
activated the DA, they went away the same as on my ROM 1.
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