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From: jfreem@uncecs.edu (Joe Freeman)
Newsgroups: comp.sys.next
Subject: Re: Realtime Mach
Summary: what is realtime
Message-ID: <1991Jan30.012919.4780@uncecs.edu>
Date: 30 Jan 91 01:29:19 GMT
References: <1991Jan29.102439.6966@canon.co.uk>
Organization: UNC Educational Computing Service
Lines: 29

In article <1991Jan29.102439.6966@canon.co.uk> wu@canon.co.uk (Siu-Fan WU) writes:
>Is realtime computing possible on the NeXT? I couldn't find anything
>in SysRef Chapter 16 (Mach Operating System). If not possible, how the problem
>is handled by the A/D conversion hardware/software available at the moment?
>In this aspect, is there any difference between the 68030 and 040?
>I would be grateful for any response. Thanks in advance.
>
What is realtime? In other words:

How much data do you need to move?

How fast?

What kind of response time to stimulus do you need?

What kind of processing needs to take place in "real time"

The A/D stuff is pretty straight forward.  It all comes in over through the
DSP and is buffered there.  That buffer is then sent, via DMA, to the ram
or disk (disk via ram probably).  There is code in the DSP driver to insure 
that it has high enough priority to keep the DMA buffers going to get the
data in.  That should leave the host free to do some processing on the data
as it comes in.


-- 
Joe Freeman	jfreem@uncecs.edu
The opinions espressed here are my own and are not shared by my employer  or
anyone else I know of.  Flames can be mailed to me or routed to /dev/null.