A89: Re: Re: Re: Re: Grayscale troubles

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A89: Re: Re: Re: Re: Grayscale troubles


Sorry about the HTML!  I think that's fixed now.
    I read that the LCD control addresses had been moved to 7000xx from
6000xx in HW2.  Are you sure that the address port doesn't exist?  Maybe
it's just moved.  (I wish I could test a HW2!)  Does anyone know about this?
    If this really can't be done on a HW2 (fairly easily) then I'm afraid
I'll have to give up on this fading thing.  Most calcs nowadays are HW2, and
there's just going to be more in the future.

----- Original Message -----
From: Scott Noveck <noveck@pluto.njcc.com>
To: <assembly-89@lists.ticalc.org>
Sent: Thursday, August 03, 2000 6:15 PM
Subject: A89: Re: Re: Re: Grayscale troubles


>
> First off, Sebastian and James: please do not send HTML-formatted messages
> to this list.  Not only is it annoying and highly disruptive to the digest
> form of this list, but it is against ticalc.org's list policy.
>
> >   HW2 is something I hadn't considered, what tricks will be necessary to
=
> > make this routine work on HW2 calculators?  What is it about HW2 =
> > calculators that makes grayscale not work?  Is the LCD address port =
> > moved?
>
> No, the LCD address port does not EXIST.  That's why it took so long for
me
> to even get a quick hack working that provided grayscale on HW2 calcs.
>
> It sounds like James has a good idea, but it is simply not feasible on a
HW2
> calc unless you can get an interrupt synched with the screen refresh (and
I
> don't even think we know that speed).
>
> > TI didn't release some timings for HW2, if I'm right.
>
> TI didn't release ANY timings for HW2.  Nor did they release any for HW1,
> IIRC.  Unless you're refering to the chip speed, which is 10 MHz on HW1
and
> 12 MHz on HW2.
>
> > That way it will =
> > flicker a lot more, because there is no way to completely synchronize it
=
> > with the LCD.
>
> That is the major issue.  With the LCD address port, you can assure that
the
> actual transition between two frames will not overlap the screen refresh,
> since it is instantaneous.  Since you have no such port on HW2, you would
> need to synch the code with the screen refresh.  The only way I can
imagine
> to do that would be to adjust the speed of int 5, and by then you have a
> huge waste of effort, if it can possibly be pulled off at all.
>
> > I don't have an HW2 calculator, but Zeljko Juric says in =
> > the documentation of his library that the "flicker bug" has been =
> > corrected.  Maybe you could take a look at his grayscale routines.  The
=
> > file is gray.c, but they are written in ASM.
>
> Whether the flicker has been corrected is a matter of opinion and open to
> interpretation.  Having written the original HW2 grayscale code and being
a
> HW2 owner (since my HW1 was stolen), I can tell you that the amount of
> flicker is, in my opinion, certainly NOT acceptable compared to what it
> could be.  I've proposed some changes before on this list, although I
> believe Zeljko rejected most of them on the basis that his testers said it
> was sufficient.
>
> Zeljko, take my word for it - there's a very prominent level of flicker
even
> when nothing is happening, such as TI-Chess' idle periods.  And it's not
> just me; when I got my HW2 and would play TI-Chess in school everyone
> commented that the flicker was annoying.  I'll rewrite the code myself,
but
> I don't think that the current code is satisfactory. . .
>
>     -Scott
>
>
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