Re: 386sx/25mhz compatibility

From: Juha Laiho (Juha.Laiho_at_iki.fi)
Date: 09/17/04 

Date: Fri, 17 Sep 2004 15:42:04 GMT

Juhan Leemet <juhan@logicognosis.com> said:
>On Wed, 15 Sep 2004 13:28:37 -0700, Nitro wrote:
>> I have 2 (very) old Dell PCs and I was wondering if it was possible to
>> install linux on them in a home network..
>>
>> Here is a link to the motherboard (specs):
>>
>> http://www.thegreenhouse.us/th99/m/C-D/31331.htm
>>
>> The machines are Dell Dimension 386sx/25mhz computers. Both computers
>> came with 4MB of ram, and I need to look into whether they can be
>> upgraded to 16MB as that seemed to be the minimum system requirements
>> to install any linux OS. I'd need to add hard drives also, since the
>> current drives are both very small (20MB).
>
>Do these have the 387 floating point processor? Paradoxically, some
>versions of Linux (kernel? apps?) seemed to require this. I have run Linux
>(old versions of Slackware and RedHat) on a 386, w/o FPP ISTR, w. 8MB, ?
>disk, but that was a long time ago, not anything like a recent kernel.

Lack of a math co-proc has "never" (ok, my experience only goes back to
kernel 0.95 or so) been a problem for Linux; there has always been an
in-kernel emulation layer. This was one big differentiating factor between
Linux and *BSD. Later on the co-proc emulation appeared also into *BSD's.
Starting at 486DX and Pentium level machines, the co-proc has been
integrated into the CPU (no 386 class CPU had a math co-proc, and
486SX was a low-end model of 486 specifically lacking the co-proc).
So, while apps have been compiled to contain also 387 floating-point
instructions, the kernel co-proc emulation layer meant that no real
co-proc was needed. 

-- 
Wolf  a.k.a.  Juha Laiho     Espoo, Finland
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