[TUHS] UNIX on S/370

Larry McVoy lm at mcvoy.com
Tue Nov 21 09:45:15 AEST 2017


On Mon, Nov 20, 2017 at 06:43:28PM -0500, Ron Natalie wrote:
> 
> 
> > I get that PDP-11 and VAX used memory mapped I/O but was that somehow
> exposed above the device driver layer?  If so, I missed that, because I had
> no conceptual or technical problem with talking to an I/O 
> 
> > channel, it was pretty easy.  And I suck at writing drivers.
> 
> There's nothing that restricts a device driver to memory mapped I/O.    You
> do what ever you have to do to initiate the I/O.   Even the x86's originally
> used special instructions to start the I/O (in/out).    The DENELCOR HEP
> supercomputer (we did this port around 1983) we had to bounce I/O requests
> off a separate I/O processor different from where the kernel was running.
> Similar constucts were used on other machines.

Yeah, that's what I thought.  But other people were saying that I/O
processors and Unix didn't mix.  I don't get that, seems like whatever
the model is is hidden under the driver, that's the whole point of the
driver design is it not?


More information about the TUHS mailing list