Re: A92: Gay Scale
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Re: A92: Gay Scale
Thanks alot for the information, I was wondering if anyone would ever get
back to me. You're engilsh is far better that my French or German (I'm not
sure where you are from) will ever be. :-)
Adam King
kinger@discover-net.net
-----Original Message-----
From: David Kühling <dkuehlin@hell1og.be.schule.de>
To: assembly-92@lists.ticalc.org <assembly-92@lists.ticalc.org>
Date: Tuesday, November 18, 1997 5:44 AM
Subject: Re: A92: Gay Scale
>Adam King wrote:
>
>> To digress from the subject of Fargo II and TI-92+, I have a question
>> concerning gray-scale rutiens.
>>
>> I am trying to write my own rutien to do gray scale. When I try to
>> move
>> three bit planes to $4440 in order, to produse gray, they look like
>> they are
>> being scaned onto screen one longword at a time, insted of being
>> blended
>> together. Is there a faster way to have the bit planes pointed to?
>> Also,
>> I have turned off all the interupts to increase the speed but it
>> didn't
>> work. I've also read something to do with screen refresh rates. Does
>> that
>> have something to do with gray scale?
>>
>
>I don't know, how graylib creares grayscales, but I can write you, how I
>made it:
>therefore you need the port at address $600010, where the address of the
>LCD memory, divided by 8 is stored.
>If you want to have 4 grayscales, you will only have to create one more
>plane, because you can use the normal LCD mem., too.
>The method is the following:
> you allocate the memory block for the 2nd plane.
> You find out the first 8-dividable address in this block
> you write $4440/8 to $600010, pause some time, than you write the
>address of plane 8 divided by 8 to $60010, and pause half the time,
>$4440/8 was shown.
>The result is, that all, which is black in plane 2 is shown lightgrey,
>all in plane1 ($4440) is shown dark grey, what is black in both planes,
>is black, and what is white in both, is white.
>The switch between the two planes can be made by a subroutine, linked to
>AutoInt 1.
>because the screen is refreshed every 4th time AutoInt 1 is triggered,
>you can show plane 1 for 8 cycles, and plane 2 for 4.
>This produces very good grayscales (you actually see no flickering).. If
>you want to do it with 3 planes, plane 3 will have to be shown 4 cycles,
>plane 2 8 cylces and plane 1 16 cylces. I tried this, too but the
>result was very bad. It is flickering very much.
>
>excuse my bad english, I know it's not perfect.
>
>PS. If you want to have my graylib, mail me personaly
>
>