The Nature Of Operating Systems :-) (Was: Re: Linux Beer Hike)

["Alex Hudson" <nospam [at] york.ac.uk>]

> > Your argument assumes that EPOC / SIBO aren't true operating systems,
> > and that is something I'd disagree completely with.
>
> Whilst my terminology may be open to misinterpretation, (hey, I'm an
> software engineer not a CS student)

Well, memory management, processes, threads, preemptive multitasking,
dynamic link library support, power mangement, privilege levels, device
drivers, event handling, TCP/IP stack, portable across multiple
architectures, I could go on.... at which point does this not sound like an
OS??

>  my point is, better to build a small  OS than take a big one and cut it
> down. Linux still is not in my book a small OS.

I think you're underestimating the size of EPOC and overestimating the size
of Linux!! Remember, EPOC32 comes in at around 6Mb w/applications? I can
still fit a distro on a floppy. Compressed, yes, but then, better than a 4:1
compression would be rather something.. I can get a graphical distro on two
floppies.

>  e.g. Amiga OS fit on a 256k ROM back in the early days. Not as
> many features, but it's a PDA not a space shuttle...

AmigaOS did bog all though? Well, it managed to get a picture of a disk on
screen ;) The filing system was absolute pants, it had no memory management,
no concept of device drivers, okay it multitasked.. I seem to recall other
OS'es being able to do that too, though ;) Besides, AOS2.0 (when it started
getting useful) was on 1Mb at least, and that *still* didn't include WB,
etc. WB3.0 weighed in at 2Mb ROM IIRC, going up to 8Mb if you wanted a
graphical
interface. No apps. A better comparison would probably be Acorns....

> My current kernel (2.3.99pre3, everything modular) is 580k, compressed.
> There's stuff I wouldn't want in a PDA on there, but where possible
> everything is modular (i.e. I have ext2, IDE and friends built in).

I'm sure IDE will be a big momma, but also, your kernel is compiled for
speed, not size. And there is *plenty* of stuff that can come out of it.

> AFAIK a RISC kernel would probably be larger too...

Yep, but not a great deal though. Possibly would need some FPU emulation,
depending on the architecture. The CISC->RISC instruction growth wouldn't be
vast, I shouldn't expect.

Cheers,

Alex.



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