> > So i was wondering, is there a way to see when to move the sprites
> > (maybe by use of vrt retr.)? I assume there is because most games i
> > played don't have this icky movement :-)
>
>You can read bit6 of VDP status register 2 to find vertical retrace:
>VDP(-2) and &H40
>
>I forgot whether zero or non-zero means the vertical retrace is active.
It's SET during retrace.
>But I'm not sure BASIC is fast enough to react to vertical retrace...
The problem is, as soon as the retrace starts the normal interrupt kicks
in. If the BASIC interrupt routine (RST 38h) is fast enough to be completed
within the retrace (or blanking) period, you have a chance you can still do
stuff.
On the other hand, maybe it's better to use a ON INTERVAL command. I'm not
sure how it works, but if it's interrupt driven it might be faster than
checking S#2 bit 6. Besides, I don't even know you CAN read S#2 in BASIC
since the interrupt routine always expects S#0!
Patriek
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