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From: metcalf@CATFISH.LCS.MIT.EDU (Chris Metcalf)
Newsgroups: comp.os.linux,comp.os.386bsd.questions,comp.sys.ibm.pc.hardware,comp.windows.x.i386unix
Subject: SUMMARY: 486DX2/66 for Unix conclusions (fairly long)
Date: 9 Jul 1993 17:13:39 GMT
Organization: MIT Lab for Computer Science
Lines: 155
Message-ID: <21k903$3q4@GRAPEVINE.LCS.MIT.EDU>
NNTP-Posting-Host: catfish.lcs.mit.edu
Keywords: OS, 486 system, X monitor/card
I've made several posts over the last month or two asking for help in
buying a 486 PC system. Here is a summary of the recommendations I
received; it is crossposted to the four newsgroups I asked for help and
information on.
The criteria I wanted to meet were:
1 Workstation-class integer performance.
2 Runs a free Unix with source code
3 Reasonable X performance under a mainly text workload
4 Price as low as possible ($2500 or less)
Point 1 (performance) obviously pushed me towards the 486DX2/66.
I initially considered the 486DX/50, but a number of people pointed out
that current boards and busses seem to be running better at 33 MHz, and
that the faster cycle speed of the DX2/66 overwhelmed its potentially
lower memory and bus bandwidth in most if not all things. I also made
sure that the motherboard I bought was socketed for an OverDrive processor
when it becomes available, so I can upgrade in a year or two.
For point 2 (free Unix), the current choices are Linux and 386BSD/NetBSD.
I chose Linux for a number of reasons, some of which may no longer be
true in six months' time:
o Linux uses the disk better: shared libraries for executables, and
virtual memory is physical memory PLUS disk swap partitions;
386BSD currently uses unshared libraries (though apparently
some people are working on this), and does the usual BSD virtual
memory technique where all virtual memory must be backed by swap.
o Possibly even more important, I liked the feel of the Linux
community better. It's less fragmented; Linux kernel and X
releases are packaged in a number of different ways (e.g. SLS),
but which package you run generally doesn't matter that much.
By contrast, 386BSD seems to be marked by infighting among
the pure 386BSD Jolitz crowd, the patch release folks, and
the NetBSD schism; while everyone involved seems very sincere
and well-intentioned, the net result is to make things harder
on the user community. Possibly as a result, the Linux user
community also appears to be larger and faster-growing, which
also points towards Linux as the OS of choice.
o Linux (as a POSIX OS with BSD/SYSV extensions) seems to be an
easier porting target than 386BSD et al (despite the fact
that I have been a BSD user exclusively for eight years...).
o Linux DOS emulation seems to be better developed and evolving.
Linux has some failings (e.g. the networking code is not as robust as
BSD's), but problems seem to be being dealt with rapidly. In fairness, I
expect that I will probably try to bring up BSD on a partition of its own,
and if it gets support for shared libraries and if one of the variants
(e.g. NetBSD) comes out as a clear winner in the user community I might
well switch to it later. Bottom line is you can't go wrong with either.
To handle the demands of a Unix machine running X, people widely recommend
16 meg, with at least 128K of cache. People do claim to run Linux/X with
8 meg satisfactorily, but apparently if you do big gcc compilations on top
of that it starts to bog down. So I opted for the 16 meg configuration;
expandability beyond that is easy, as long as your board supports caching
the higher memory. There's often a choice of 70 ns or 60 ns memory;
you might be able to squeeze one fewer wait states out of 60 ns memory,
but with most motherboards you'd be riding outside the specs for the memory.
Disk space is simple: figure out how much you need, and double it.
I decided to get a 340 meg disk, which seems ridiculously more than
necessary for me today, so it will probably be stuffed full by the end of
the year. Disk prices dropped this month anyway, which was a good excuse.
Don't bother to get a caching controller if you're mainly running Unix,
since Unix does caching in main memory anyway.
You will need to decide if you want to get a SCSI adapter and a SCSI disk;
however, it will definitely be more expensive, since you need a separate
SCSI controller (about $200), and SCSI disks are often more expensive
than IDE disks. Furthermore, it is said that for disks up to 500MB,
SCSI probably won't give you any noticeable performance improvement
unless you are running a heavily used disk server.
Point 3 (X) was the hardest for me to figure out, since there is an
incredible variety of graphics cards and monitors. I decided to go for a
color 15" flat-screen noninterlaced monitor, which is about the smallest
you can get and still run two 80-column pages side by side on the screen.
This may be a false economy; lots of people suggested spending a little
more for a really nice monitor. We shall see how it works after a week
or so. Interestingly, I measured some display-diagonal lengths with a
ruler, and found that a good 15" can be almost as big as a 16" or 17":
15" Mag Innovision 14.3" (what I'll be buying)
16" Sun Trinitron 14.7" (what I use at work)
17" Morse 15.7" (if you want to pay $300 or so more)
Graphics cards are harder. I decided against the higher-priced
graphics cards such as the ATI Ultra Pro or S3-based cards; if I had
been looking for graphics performance, this is what I have bought.
Instead, I bought a Cirrus 5426-based card for $95, which offers
reasonable performance today with XFree86 1.3, and significantly better
performance when XFree86 2.0 is released.
One question I explored was whether I could use a DEC color monitor such
as the VR290 with a VGA card, since we have some spare monitors at work.
The answer was basically: "maybe", if you can cobble together a printed
circuit-board (details on request, forwarded from Mattis Andersson); and
"yes", if you want to shell out about $500 for a much more general-purpose
box from vendors like EXTRA, In-Line Systems, or EISI. I decided to
just buy a new monitor.
Point 4 ($2500 price) managed to work out; here's the breakdown of the system:
486DX2/66 VESA LB with 256K cache $1375
(package includes 3-button mouse, Mitsumi
keyboard, heatsink fan, 1M memory, 3.5"
floppy, 42M HD, cheap 14" monitor and card)
upgrade to 16M 70ns RAM $601
upgrade to 340 meg HD $225
upgrade to Mag Innovision 15" monitor $248
upgrade to Diamond SpeedStar Pro $86
TOTAL $2535
This price doesn't include full DOS 6.0 ($47) or Windows ($40), which are
sometimes unbundlable; it does include 5% Mass. tax.
There are some things you want to make sure to look for on your
motherboard: you may want to check that it will cache >16M of memory,
which can be a problem. If possible, you probably want to get a
write-back cache instead of a write-through cache, as well. For the
serial UART, you should also try to either get a 16550 (not a 16450),
or get the chip socketed so you can upgrade it; it will help your
Unix not to have to take an interrupt for each character transferred.
Also look for a reputable BIOS supplier such as AMI or Phoenix.
The retailer I worked with is PCs for Everyone, 24 Thorndike Street,
Cambridge, MA 02141, (617) 866-0068. I got a slightly better price from
KC Computers (contact kcc@pt.com), and Dee-One, both mailorder companies.
Prices were around $200 higher from some of the larger mailorder outfits
like Gateway, Insight, Ares, or Zenon. Zeos delivered the highest
quote for a similarly-configured system. I would suggest Gateway as the
mailorder company to beat in terms of price, support, stability and user
confidence, based on what I've heard; Insight is good for the user who
needs less hand-holding; I've heard good things about Ares; and Zenon
has gotten some bad press on the net lately. (I'll mention Dell just
to say that they're significantly more expensive, but you will get the
best hardware, good support, and so forth.)
An excellent source of further info for all this is Eric Raymond's
two guides, archived as pc-unix/hardware and pc-unix/software (e.g.,
at rtfm.mit.edu:pub/usenet/news.answers); the most recent version, 16.0,
was posted on 6 July 1993. Many thanks to Eric for making this document
available and keeping it updated.
And many thanks to the dozens of people who sent me email with various
suggestions about different aspects of the PC buying game!
--
Chris Metcalf, MIT Laboratory for Computer Science
metcalf@cag.lcs.mit.edu // +1 (617) 253-7766