[Coco] Driverwire server

[Roger Taylor]

At 03:33 PM 3/11/2009, you wrote:

>Roger,
>
>This is a good approach.  Some time back, I tested a similar scheme
>(not under NitrOS-9) and had acceptable results.
>
>In NitrOS-9, though,  it gets a little touchy, depending on how fast
>the server can respond to the client CoCo's query.  Under NitrOS-9, an
>SCF driver could be written which would hook into the F$VIRQ (virtual
>interrupt) vector.  This is called by Clock at a rate of 60 times per
>second; for the bitbanger, the response back from the server would
>have to be quick, because the driver could not afford to wait very
>long in its IRQ routine for a timeout condition.
>
>It's an interesting problem, but with the right protocol and a little
>testing, it could probably be pulled off under NitrOS-9 without being
>detrimental to the responsiveness of the operating system.
>
>Boisy

Yes, the server has to respond quickly and if interrupts are used to 
knock on the server's door 60 times a second, I'd go with a short 
block size.  Ofcourse we all realize that the throughput drops a lot 
using a scheme like this.  It's a trade-off situation:  sit and loop 
for a start bit or run other programs while not missing anything 
"coming in on the bitbanger port".  I haven't done any throughput 
math on any of this.


-- 
Roger Taylor

http://www.wordofthedayonline.com