[Oberon] serial port & tasking.

eas-lab at absamail.co.za eas-lab at absamail.co.za
Wed Jun 18 19:50:44 CEST 2003

previosly: Re: [Oberon] monitoring an RS-232 interface.

peter_easthope wrote:

> ... snip ...
> > WIth this setup, one observer will monitor transmissions 
> > from computer to modem and the other will monitor 
> > transmissions from modem to computer.  Perhaps one 
> > machine with two serial ports is capable of monitoring 
> > both lines.  No doubt this would work with Unix but I 
> > have not tried running two concurrent V24 tasks in Oberon.
> > 
> The serial port(s) only need attention when their FIFO (buffers)
> are getting full or empty for Rx and Tx respectively.
> Has n-o got the ability to interrupt for modem or mouse ?
> I don't think so. Older machines had smaller buffered ser-chips
> and would be more likely to 'overflow'. 
> Normally, the ser-mouse and ser-modem ARE 'sharing' tasks.
> Although not symetrically. From the papers which you kindly posted:
> " Mouse and keyboard buffers are polled at each task switch in the 
> loop.."

On secomd thought:
 mouse (serial port) and keyboard are normally interrupt driven.
They put their 'receipts' in buffers at standard locations..
It would be absurd for n-o to modify this behaviour.
Also, that Ctrl/Break is apparently not 'maskable' means key & mouse are
  interrupt driven.

" Mouse and keyboard buffers .." refers to the buffers where the 
interruped receipts are stored;  not the hardware buffers in the chip.

To get an idea of the speed multi-tasking capabilities you may want a
3 ser-port setup - need one for the mouse. Then have the 2nd port loop
around to the 3rd port; using a routine to move eg. a file from 2nd to
3rd.   As an initial test, I guess you can confirm 2 separate V24.Panel
on the same machine can mutually communicate. 

Chris Glur 

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