[Coco] Interrupts

[rcrislip]

On Sunday 02 December 2012 16:04:03 Willard Goosey wrote:
> 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

Hi Bill and Willard

Thanks for the explanation. The idea of using virual memory on the CoCo is so 
cool. I realize it really is nothing new, but to hear some folks in the M$ 
world talk about it you'd think it was. 8-)