[Coco] Interrupts

[Willard Goosey]

On Sun, Dec 02, 2012 at 03:15:39PM -0500, rcrislip wrote:

> What's VRN?

As Bill said, it's a kernel-level device driver package, that supports
several interesting functions...

Through the VI device descriptor, it brings the 60Hz virtual interrupt
system (one of the kernel's internal goodies) to user processes.  Open
/VI and it sends you a character 60 times a second -- which you can
then use to make your program do things when it recieves a character
on that path.  This mimics the Sierra on-line driver needed for the
AGI engine (kings quest, lsl, etc).

The FTDD descriptor does largely the same thing, but also has
memory-allocation functions.  It mimics the Flight Sim II device
driver.

It also has a NIL descriptor, because the OS that doesn't have a null
device is incomplete. ;-)   

VRN itself is the device driver that runs the descriptors.  It was
distributed as a seperate package for OS-9 and is part of the standard
NitrOS-9 kernel modules.  

Willard
-- 
Willard Goosey  goosey at sdc.org
Socorro, New Mexico, USA
I search my heart and find Cimmeria, land of Darkness and the Night.
  -- R.E. Howard