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From: flynn@yoda.eecs.wsu.edu (Patrick J. Flynn)
Newsgroups: comp.sys.next
Subject: Re: Buy Memory; Don't Laugh
Message-ID: <1991Jun24.180123.9452@serval.net.wsu.edu>
Date: 24 Jun 91 18:01:23 GMT
References: <28652826.11D5@deneva.sdd.trw.com>
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In article <28652826.11D5@deneva.sdd.trw.com> thomsen@spf.trw.com (Mark R. Thomsen) writes:
>
>We asked our local NeXT rep to borrow his ND for a day and
>managed to get the software mostly running. 40MB CPU RAM
>and 16MB ND RAM. Got good animation of ozone hole opening and
>closing. Did the rest of the work on grey cubes and got it
>to run.
>
>We go to the gathering last Friday. We asked for a ND to be
>provided. It was. But we did not mention memory. The hard
>disk (in cube provided by someone else - not NeXT) did not
>have room for the app. The configuration was 16 MB CPU RAM
>and 4 MB ND RAM. Started deleting stuff from HD and barely
>could run. Everything ran slow. (We sling around 3MB images
>like chips at a poker game).

Those of you considering the purchase of ND systems might be interested
in this future NextAnswer created by Sharon Zakhour at NeXT (posted with
her permission).  I asked the questions, she was nice enough to answer them.

I was intrigued by the following items in the answer:

1. The i860 pages via the '040.  I wouldn't want to have an I/O bound
   ND board, so load up on ND memory, folks.

2. You can't memory-map the ND's VRAM.  This may spell Big Trouble for the
   people wanting X on the ND system.  As far as I know, all the current
   NeXT X implementations memory-map the frame buffer.

TTFN

Pat "My ND arrives next week, drool drool" Flynn

---- snip snip snip ----

NeXTdimension memory i860

Q. I've purchased a NeXTdimension system and wish to expand the memory.
What performance advantages can I expect to gain from adding memory to
the ND board as opposed to the CPU board?  Is there a mini-Mach running
on the i860?  Can the i860 swap to disk?  Can I memory-map the memory on
the ND board?

A:  The DRAM on the NeXTdimension is used for displaying all windows which
appear on the ND monitor.  The ND board is driven by a Mach loadable device
driver (which loads into the Mach kernel on the host) and a NeXTdimension
screen driver, part of  which loads into the WindowServer, and another part
which loads into the i860.  This i860 software consists of a mini Mach-like
kernel, specially designed to support low-level PostScript drawing and virtual
memory for window backing stores.  It is NOT possible to program the i860
directly -- see NeXTanswer color.648 for more information.

Neither the DRAM nor the VRAM on the NeXTdimension can be memory mapped by
the application.  When it becomes necessary, the i860 pages to disk via
the host 040 -- it does not write directly to disk itself.

Whether you increase memory on the 040 or the ND depends upon how you plan to
use the system.  In general we recommend that you keep them fairly balanced.
If you are going to be keeping lots of windows on the ND system then we
suggest that you keep the memory on the i860 somewhat ahead.  The less paging
you do the better.  You cannot extend the VRAM [video ram] on the NeXTdimension.

The NeXTdimension-related files on the 2.1 Release (ND systems only) are
located as follows:

ND PostScript Driver:

In the directory /usr/lib/NextStep/Displays/NeXTdimension.psdvr:

reloc		dynaloads into WindowServer
ND_MachDriver	loaded into Mach
NDserver	loads i860 code and provides I/O support

NOTE:  The size of the VM space on the i860 is directly related to the
VSIZE that ps will report for the NDserver task.  This task shows up in a 
"ps aux" as:

root       149   0.0  3.4 28.3M  280K ?  S    40:47 (NextDimension) -NDSlot 2

CPU use by this task directly reflects I/O activity, including paging,
by the i860.

Video Support:

/usr/include/appkit/NXLiveVideoView.h		include file for video view
/usr/lib/NestStep/GraphicsPackages/video_reloc	dynaloads into WindowServer
/usr/shlib/libvideo_s.A.shlib			shlib image
/usr/lib/libvideo_s.a				shlib archive

Demos & Examples:

NeXTtv 		video/grab Demo
ScreenScape 	video out Demo
VideoApp 	generic video Demo and Example

See also: 
color.648 for more information on the i860

color.607 for information on color lookup tables

video.578 for information on video window size for the NeXTdimension

performance.739 for performance issues involving large amounts of bitmap data

QAxx

Not valid for 1.0
Valid for 2.0
-- 
+-----------------+--------------------------+----------------------------+
|Patrick J. Flynn | School of eeks, er, EECS | Washington State University|
+-----------------+--------------------------+----------------------------+