🚀 go-pugleaf

In article <annius.721647206@freyr> A.V.Groenink@research.ptt.nl writes:
>leo@dcs.warwick.ac.uk (Leo Hendry) writes:
>
>>It is slow because Atari STILL haven't made use of STe's hardware scrolling
>>(which I assume is available on the Falcon) in TOS.  Apart from the slowdown
>
>I suspect you don't even know what the 'hardware scrolling' facilities of the
>STE actually are (and the same for the other post in this thread mentioning the
>fact that `nobody uses the STE hardware scrolling'.).

I know that the screen start address to be varied by a word at a time allowing
vertical scrolling by adding/subtracting the number of bytes in line times the
number of lines you wish to scroll by.
  I don't know whether you can specify a vertical offset (where the screen
starts scanning at the screen address+offset and after reaching screen
address+size of screen continues at screen address), but probably not since
this can easily be done in software using the timer B counter.
  In the case of horizontal scrolling you can specify both a horizontal offset
and a number of bytes to skip between scan lines to give a virtual screen
wider than the one displayed.
  Of course, these features only apply to the whole screen - to scroll in a
window you must use the blitter, which should be fast enough, however many
programs just redraw the whole window when it is scrolled (Which can be faster
if no blitter is fitted).

- Leo

>
>--
>Annius Groenink  --  Universiteit Utrecht  --  PTT Research Leidschendam