Subject: Re: Setting up a T1 and email
To: None <port-vax@NetBSD.ORG>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: port-vax
Date: 07/16/1998 07:15:51
> DMA input sounds like a great idea but it would add a lot of
> complexity, in regular (cooked) mode the CPU will just grab each
> character right back out of memory one at a time anyway to decide
> whether it does anything special,

Sure, but that's cheaper than, for each input byte, taking an interrupt
*and* doing that processing.

> and then on the rare occasions when you get to do full bore binary
> input it will need basically a whole second version of the receive
> handler that just packs up a buffer at a time at a time and ships it
> in.

Looking at the Z8530 driver, I think it already does this - it snatches
characters out of the chip and stores them in a ring buffer in main
RAM, and they get processed from there.  It would only ease the load on
the main cpu if this stuff were DMAed into that buffer instead....

					der Mouse

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