Re: A85: Got it to work, but I still have questions...
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Re: A85: Got it to work, but I still have questions...
At 22:43 1998-05-13 -0400, you wrote:
>
>I would like at least one response to #1 and #2. Thanks.
>
>1) I recall something about Usgard having interrupts, but I look at my
>op-code sheet and I don't see anything like INT X or whatever. What do
>you do to call an interrupt in Usgard and how does it actually work?
>These weren't built into the calc and ZShell just didn't acknowledge them
>were they?
You don't call an interrupt explicit (which you can on the PC), an
interrupt "happens". There are excellent documentation about this
though in the Usgard doc files.
>4) I'm just full of questions. This IS the last one though. Would it
>be possible to simulate page flipping of the video screen on the
>calculator? If you don't know what flipping is, it's kind of like
>drawing a picture behind a piece of cardboard, then removing the
>cardboard to make it look like the drawing was created instantaneously.
>It's used for creating smooth, flicker-free animations (that commonly
>require the whole screen).
Yes, it's possible. As someone else said, you could always use
the graph_mem to draw on, and then copy it to the video mem. Even
though that's fast, there is an even faster method; you can actually
change where in the RAM the video mem should be (that's how grayscale
graphics work). The LSB of the address must be 0, and the MSB must
be >=$C0 though. I've never seen (or heard of) any game using this
technique though.
--
Real name: Jimmy Mårdell "can't go mucking with a 'void *'"
IRC......: Yarin // Apple's MPW C compiler
Email....: mailto:yarin@acc.umu.se
Homepage.: http://www.algonet.se/~mja/
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