Re: A86: Re: Grayscale

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Re: A86: Re: Grayscale


yeah, ldir running 1024 times would take ~21504 cycles, if the z80 is
running at 5 million instructions/sec (i'm pretty sure it's slower),
that's just under 1/200th of a second, which leaves no time for regular
processing.

the other problem is that this doesn't actually solve anything because
you still have to have the space allocated on ram page 0.  it's better to
move some of the asm code to other places.

the standard method of just switching the screen address takes very
little time at all, there's no way short of hardware modifications to
speed it up.

and how dare you have any sort of creative thought!?? :)

-josh

On Thu, 20 Jan 2000 19:51:10 -0700 "Kirk Meyer" <kirkmeyer@bigfoot.com>
writes:
>
>No. An ldir operation of that magnitutde executed every interrupt 
>would hog
>the space and make things run unallowably slow. Also, your idea of 
>only
>switching certain pixels is insane, because flicker occurs if you 
>don't
>change the screens fast enough.
>
>I'm not quite sure what is wrong with the current method of using 
>$FC00 as
>primary and $F200 & $F600 as secondary and tertiary planes.
>
>----- Original Message -----
>From: Joe <joeknoll@myself.com>
>To: <assembly-86@lists.ticalc.org>
>Sent: Thursday, January 20, 2000 4:49 PM
>Subject: A86: Grayscale
>
>
>> I just had an idea about grayscaling.  So... most people don't use 
>all
>their
>> storage memory... so you could have extra screens stored there 
>(instead of
>> putting them in the back-end of the dedicated ASM space... well, you 
>could
>> do both).  My guess is that (haven't read the code you guys have 
>posted)
>> that to switch to another screen you guys' basically switch the 
>port
>> location (does that automatically "re-write" the screen?).  So... 
>with
>fancy
>> work you can use the places in RAM page zero to store more screens.  
>I
>know
>> the screen port can't be changed to a value that low; but you could 
>copy
>the
>> stuff over to page 0.
>> okay... overview:  swap out the RAM page with another empty or close 
>to
>one
>> (someone with a full calc would get an "not enough memory error").  
>Then
>the
>> blocks of memory there could be either copied to page 0 and then the 
>port
>> could be swtiched.
>> Of course I don't know if this has already been totally tried out 
>by
>> "everyone" and the z80 just isn't fast enough or the screen isn't or 
>what
>> not.  I appoligize in advance if this just sounds lame; but I 
>haven't ever
>> followed the grayscale threads and I've never used any in any ASM 
>progs I
>> write.
>> Another idea:  you could write a side program for the computer that 
>would
>> determin exactly what pixels need to be over written and stuff to 
>make the
>> gray scale... that would most likely result in larger code... but 
>possibly
>> faster grayscale without swapping pages... who knows...
>> --Joe
>
>

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