[Coco] NitrOS-9 GET/PUT buffer questions

[Robert Gault]

James Dessart wrote:
> I've got a couple of questions about the Get/Put buffer behaviours on
> NitrOS-9. So here we go:
>
> Where does NitrOS-9 allocate space for the buffers? Is it in the
> process's address space, or in some system buffer?
>
> What's PutBlk's behaviour when using a logic operation for copying a
> 2-bit buffer to a 4-bit screen?
>
> Is there a way to access the screen buffer directly through OS calls?
>

Can't answer all the questions. You are asking about the Windowing system calls 
which normally would be issued with the display command. For example,

display 1b 2d 1 1 00 10 00 a0

PutBlk group1 buffer1 at x=16 y=160

There is no conversion of data if you mismatch the screen type and data. I 
presume there must be room in your process space to map in the buffer or you 
won't be able to work with it. The buffer itself probably also exists in system 
space.

If you want to use system calls instead of display, you will just write the 
above data to a screen with the os9 I$Write call which is what the command 
display does.
That will require opening a path to the correct screen.