[Coco] Assembly lang questions

[Dave Philipsen]

As Art explained, the CoCo does not comply with ASCII standards.  So the ASCII value for space (32) does not correspond with what the VDG of the CoCo thinks. Reverse video characters are just that; reverse video.  I believe the value used by CoCo to represent a space is 96. An inverted video space is 32.

I haven’t watched the Long Branch Never video but he must not be using the CHROUT ROM routine to display characters on the screen because it will do the translation for you from ASCII to CoCo VDG.  If you decide to write your own routine that writes characters to the screen you must be aware of that.  Some of the VDG characters correspond correctly to ASCII and some do not.

Dave

> On Oct 11, 2018, at 6:15 PM, Salvador Garcia via Coco <coco at maltedmedia.com> wrote:
> 
> Hi all, I am following the Long Branch Never video where Paul  displays the message HELLO WORLD on the screen.
> He uses char(32) for the space, but it displays as black. To fix this he substituted the ASCII from 32 to something else (I think it was 76?) That printed out the space as expected. What I did not understand is why chr(32) displayed as a black box.
> 
> I understand that reverse video chars are lower case, but I never heard of a lower case space :-).
> 
> He later modifies the program to start displaying chars at $500 which pushed the text line below the copyright notice. The cursor blinked one or two lines above the displayed text, so this got me wondering. Is there any way to know the cursor's position?
> 
> I am enjoying this video series and also Steve Bjork's series on COCOTALK!
> 
> Salvador
> 
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