Re: Coding for IIgs 2 - working on screen memory

[Toinet <antoine.vignau@laposte.net>]

On 25 déc, 04:38, lyricalnanoha <lyricalnan...@usotsuki.hoshinet.org>
wrote:
> Ouch.  Got wedged trying to pull this off, perhaps I'm interpreting the
> hardware wrong.  Looks like it's trying to write in bank 0 instead of bank
> 1.  (I'm using the //e way to access bank 1, according to the docs I have,
> rather than trying to go '816 and do it that way, as I don't yet
> understand 65816 mode.)
>
> The way I *wrote* the code, I meant it to leave ][+ space readable while
> making //e space writable.  (It doesn't seem to have done that.)  Whether
> I .org this high or low, it still gets wedged.  (There's nothing
> IIgs-dependent about the code beyond the C029 thing.)

Note that the official IIgs screen location is at bank $E1. Writing to
bank $01 (fast RAM) is great but once you master the shadowing
process.

If I were you (and God knows I was a long long time ago), I would
avoid writing standard II code on a IIgs, the IIgs is a fun machine
and its 16-bit processor, though simple, is easy to understand.

By the way, at least, use ProDOS instead of DOS 3.3.

>
> I'm trying to create a memory environment conducive to plotting pixels in
> 320x200x16 mode.  The palette approximates EGA.
>
> -uso.
>
> setty:    lda       $C029
>            ora       #$80
>            sta       $C029

When you are ready to go for IIgs coding, use TSB.

>            bne       @1
>            bne       @2

Replace with BPL

As already said by Charlie, the $C004/$C005 softswitches require a STA
not a BIT.

Good luck and Merry Christmas,

Antoine