Re: Andrew Tanenbaum on the origins of Unix/Linux

From: Greg Hennessy (me_at_privacy.net)
Date: 05/21/04 

Date: Fri, 21 May 2004 20:11:46 +0100

On Sat, 22 May 2004 00:32:30 +1000, "John" <news1@saunders.id.au> wrote:

>"Greg Hennessy" <me@privacy.net> wrote in message
>news:6vera0phkek8gg0agvvqdn5julrsodq9a7@4ax.com...
>> On Fri, 21 May 2004 03:55:39 +0000 (UTC), bob prohaska
>> <bp@imln8.berkeley.edu> wrote:
>>
>> >It seems to me that the sudden explosion of *nix for the i386
>> >architecture must have been initiated by some revelation about
>> >how the hardware worked. In very short order Minix, Linux and
>> >386BSD hatched on the i386.
>>
>> AIR Minix ran just fine on ia32 < i386.
>
>A memory management unit (MMU) is required to support a
>real Unix because of the semantics of fork().

Agreed.

> The segment
>registers of the 8086/88 and 80286 get you part way there,
>but it imposes a 64K limit on code, data and stack.

/me shudders at the recollection of near and far pointers.
Primitive when compared to vax macro32 I was writing at the time.

>Unix didn't explode on PCs until the 386 with its paged
>memory management unit came out. Similarly the 68020
>started the Motorola Unix explosion (Sun, Apollo,
>NetBSD/Amiga&Mac).

I can remember a rumour which suggested that the original A1000 amiga
design had some form of MMU support. An interesting what if.
 

greg 

-- 
"vying with Platt for the largest gap
between capability and self perception"

Relevant Pages

  • Re: interrupting for overflow and loop termination
    ... >> and similar languages to use other tricks that don't require hardware support. ... running on multiple MTAs can fairly well hide memory latency (well ... Object IDs are generated by newusing a PRNG. ... The MMU model can be ...
    (comp.arch)
  • Re: FreeBSD or other BSD for no-MMU ARM processor ?
    ... >>ARM processor which does NOT have an MMU (Memory Management Unit)? ... but that a number of companies sell support and a number of embedded ...
    (freebsd-hackers)
  • Re: Which 32 bit cores support full Linux?
    ... believe the one big requirement is that there has to be a MMU. ... of the three FPGA vendor's cores are available with a Linux supported ... That support has been ...
    (comp.arch.fpga)
  • Re: Andrew Tanenbaum on the origins of Unix/Linux
    ... | a MMU. ... The Fortune Systems "32:16" was built in 1981 and ran Unix on a plain ... Only text, data, and stack were really needed for Unix, but since ... Obviously, with such an MMU we couldn't support "paging", only ...
    (comp.unix.bsd.freebsd.misc)
  • Re: Best low cost uP for full Linux
    ... External bus support for more than 256MB of RAM, ... chip does not have a MMU and you are forced to use uCLinux, ... It looks like several of the V4 flavors have MMUs, so if you're extremely lucky some Linux jock may have even gotten the code working for it already. ...
    (comp.arch.embedded)