Re: Help Wanted!

[David Given <dg@cowlark.com>]

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On Tuesday 27 September 2005 22:06, Hans wrote:
[...]
> Why not?

The short answer is because the BIOS is not reentrant, which means it can only 
do one thing at a time. Remember the bad old days when accessing the floppy 
disk would make the system freeze? That's the BIOS' fault.

Also, the BIOS is *extremely* basic. The BIOS elevator algorithms for MFM hard 
disks sucked hugely; I once ran big Linux on a 386 with an MFM drive, and was 
amazed at just how much faster Linux' disk access was, simply because it was 
scheduling the I/O transfers more efficiently. I'm not even sure the BIOS 
does DMA. Remember that the B stands for Basic...

Now, it *might* be possible to multitask during a BIOS call provided only one 
task was accessing the BIOS at any time. You still wouldn't be able to, e.g., 
access the hard disk while the floppy drive was in use, but at least the 
system shouldn't just freeze.

[...]
> I would forget about ARM since they have a very good uCLinux port and gcc
> support.

Yeah, but uCLinux is still very large compared to an ELKS kernel.

(BTW, someone has told me via email that they have Minix 2 running on a i86 
machine, but the TCP/IP stack tends to eat most of the available memory. So 
it does actually work.)

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