[SWLUG] OS for old hardware

[bryn]

Hi there,

> The temptation is to install a suitably old version of whatever
> manufacturer's operating system one is devoted to. In the Windows (and DOS,
> by implication) world, later versions have substantially greater hardware
> requirements; I'm wondering if Linux is more forgiving of hardware. (One
> naturally assumes that Linux is preferable to DOS/Win for any given era ;-)

There's a few micro-distros around which are specially aimed at
old/low spec hardware, a google turned up links:

http://public.planetmirror.com/pub/xdenu/
http://tinylinux.sourceforge.net/
http://savannah.nongnu.org/projects/rule/

Not used any of them but savannah looks like the more active project.
Looks like they've had some grief over redhat's decision to start
phasing out legacy support tho.

> There seems to be a distinction here between system (i.e. always running)
> software such as the kernel and perhaps X, and user apps. 

Yup. You can compile a kernel specifically to run on particular
architectures. For x86 the minimums a 386 because it was the first to
get an MMU. Just checked with 'make menuconfig' on the kernel and it
offers optimizations for the following:

	386
	486
	586/K5/5x86/6x86/6x86MX
	Pentium-Classic
	Pentium-MMX
	Pentium-MMX(gcc>31)
	Pentium-Pro/Celeron/Pentium-II
	Pentium-Pro(gcc>31)
	Pentium-II/Celeron(gcc>31)
	Pentium-III/Celeron(Coppermine)
	Pentium-III/Celeron(Coppermine)(gcc>31)
	Pentium-4
	Pentium-4(gcc>31)
	K6/K6-II/K6-III
	K6-II/K6-III(gcc>31)
	Athlon/Duron/K7
	Athlon/Duron/K7(>gcc31)
	AthlonMP(gcc>31)
	Elan
	Crusoe
	Winchip-C6
	Winchip-2
	Winchip-C6
	Winchip-2A/Winchip-3
	CyrixIII/VIA-C3/VIA-C5

>I suspect the
> kernel is not *that* sensitive to CPU speed, but, for instance, how
> sensitive to graphics card era is X, and to CPU (and RAM?) specs are user
> apps. I admit apps are diverse, so let's assume apps of middling demands?

getting support for legacy cards is probably easier than cutting-edge
3d accelerators. Unless it was a particularly exotic (or rubbish!) one
a stable driver probably exists, but don't expect much more than twm
and simple apps - you're right, the gimp (and gnome) would be hellish
on something like that :)

> By 'sensitive' I mean that one could -- assuming no pentium-specific m/c --
> run any version of the kernel on a 486 and still be able to work
> efficiently, but anyone trying to run the latest version of the Gimp on such
> a processor might end up needing counselling!

Hmm. Not sure about that. You can make a pretty huge differences in
performance by changing compile time options on the kernel. For e.g.
even with the target set to 386 it's not hard to come up with a kernel
that won't boot on old machines, just include enough generic drivers
and it'll get too big for machines with limited ram (or atleast so big
they are painfull to run) - this is the big reason why redhat's later
installers are so horrendous on old hardware. They have one biggie
(and smp versions) to support just about all common hardware and
slower machines with little ram choke badly.

> In terms of a very notional graph, how steep is the plot of Linux version
> (ignoring distribution issues) against CPU-required?

I am totally guessing here but I would think it's pretty flat in
general but very hard to measure meaningfully. Unless you're compiling
in kerenel options which bring a specific perfomance hit like advanced
packet filtering or some of the debug / safety harness code. That's
one beauty of the linux kernel, because you control the options used
to build the kernel, it's pretty much down to you what it's optimized
for.

Generally the effort seems to be toward constantly improving the
efficiency of the core code and only expanding the time/space
requirements when safety or specific features require it.

If it were me, I'd use gentoo or debian for the low spec machines. I'm
not overly familiar with debian but understand you can install from 4
floppies. Gentoo's nice because it builds everything from source so
you have more (and easier!) control over what gets installed and how
it is optimized. If you started from a "stage 1 tarball" you could
build every part of the OS to suit the machine and it really isn't as
hard as it sounds - I've only been using it a few weeks and it already
feels like home!

> On the contrary, it's great that people are prepared to spend so much time
> and effort giving such comprehensive and detailed advice. More power to you,
> I say!

cheers!

Bryn