Re: [colorforth] Setting a pixel on the screen

["Ray St. Marie" <ray.stmarie@xxxxxxxxx>]

Ya, gosh, how many programs do I use this! Several! It's funny cuz
i've never not done it. It's Byte addressing, Please notice that you
are just setting things up with the 2 leftshifts so that the
definitions for ! and @ which include the definition   a,  ( defined
as 2* 2* ) which will return you back to word addressing. I suppose
this is for Chuck and for ease of use.

Your guess is better then mine. :-)

On Wed, May 28, 2008 at 7:01 AM, Jason Kemp <jason.kemp@xxxxxxxxxxxxxxxx> wrote:
> ...And that's not right because ! stores a double word and I only want a
> word (16 bit colour).
>
> Block 34 (icons) has !w which stores a 16 bit word to a byte address.
>  That's what I need instead of 2/ 2/ !
>
> Also, on http://www.colorforth.com/forth.html it is stated "Data are
> addressed as 32-bit words, not bytes."  I'm not fully clear on how this
> works so I need to look harder.
>
> Jason Kemp said the following on 28/05/2008 11:27:
>>
>> Hi Ray,
>>
>> Thanks for all the encouragement.  I cracked it on Friday and was
>> intending to reply, but I'm trying not to touch the computer over the
>> weekends now and Monday was a bank holiday too!
>>
>> : pixel show black screen ffff 400 400 1024 * + 2* 1e80000 + 2/ 2/ !
>> keyboard ;
>>
>> It needs a 2/ 2/ because ! multiplies the address it is given by 4.  This
>> must be something to do with addressing doublewords as opposed to bytes--I'm
>> sure it's something quite obvious to most but it's taking me a long time to
>> build up a picture of what's going on here.  Are addresses in colorforth
>> stored as the count of doublewords rather than a true address?
>>
>> Jason
>>
>>
>>
>>
>> Ray St. Marie said the following on 27/05/2008 20:23:
>>>
>>> rethinking my previous post to this question...
>>> Hi Jason,
>>> Ray here
>>>
>>> On Tue, May 20, 2008 at 4:41 PM, Jason Kemp <jason.kemp@xxxxxxxxxxxxxxxx>
>>> wrote:
>>>
>>>>
>>>> Good evening all,
>>>>
>>>> I have been attempting to set a pixel on the screen to white.  Please
>>>> show
>>>> me what I am doing wrong:
>>>>
>>>> : ohno show black screen ffff 400 400 1024 * + 2* 1e80000 + ! keyboard
>>>> ;>
>>>> Only the ffff and the 1e80000 are in hex.  The screen is 1024x768,
>>>> 16-bit,
>>>> VESA 117h.
>>>>
>>>> Thanks,
>>>> Jason
>>>>
>>>>
>>>
>>> Jason, have you tried the word color after ffff, to set the color, as
>>> in...
>>>
>>> : ohno show black screen ffff COLOR 400 400 1024 * + 2* 1e80000 + !
>>> keyboard ;
>>>
>>> I happened to be looking in an old source and reading the word SWITCH.
>>> In the top of the word we see an example of writeing to AGP before
>>> switching to keyboard.
>>>
>>> Karig has a nice look at it :
>>>
>>> http://www.karig.net/os/cf/g.htm
>>>
>>> Halfway down the page. All of the rest of that page are examples of
>>> 'emit'ing pixels to the page.
>>>
>>> Good luck with this, Jason. Please keep me in the loop, your
>>> experiments, as I'd like to try them out as well. :-)
>>>
>>> All the best,
>>> Ray
>>>
>>>
>>
>>
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>
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-- 
Raymond St. Marie ii,
colorforthray.info

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