are there problems with this email? - what is a disc on chip? - beginner's question

[steven james]

Greetings,

For many mainboards, 256K is the limit due to not having all of the pins
connected. 512 is a harder limit imposed by the 32 available pins on the
flash chip. DoC gets around that by having page flipping built in (sort of
like EMM from back in the 8088 days).

Newer chipsets and motherboards get around the address line limit using
either LPC interface (a serialization of ISA into a much smaller pin
count), or firmware hub (more or less Intel's take on LPC).

It is quite possible to get LinuxBIOS and a loader such as Etherboot into
a conventional flash. From there the options for loading the kernel
include network, IDE drive, or CF. A little work will allow floppy or
CDROM.

G'day,
sjames

On Wed, 8 Jan 2003, Antony Stone wrote:

> On Wednesday 08 January 2003 10:46 pm, Alessio Sangalli wrote:
> 
> > Antony Stone wrote:
> 
> > > Because they do not have a large enough capacity.   Standard BIOS
> > > chips are
> > > 2megabits (= 32 kilobytes), which is not neough to hold a Linux kernel.
> >
> > 256KB perhaps?
> 
> Sorry - yes, 256kbytes is correct.
> 
> > And how many mbits are those disc-on-chip?
> 
> The ones most people use (MD-2800-D08) are 8 megabytes.
> 
> > So even if I have a flash big enough to store a complete kernel, I won't
> > be able to use it with linuxbios? Only for diskless boxes perhaps? What
> > if I do have an hard disk in the system?
> 
> If you have a flash chip big enough fro a kernel I don't think it'll fit into 
> the normal 32 pin socket used by 2 mbit BIOS chips.
> 
> However, if you can get a kernel into a chip, then you can certainly have 
> your root fs on a hard drive or across a network.
> 
> > I'm surprised, I though it was easy to find few megaBYTES flash chips
> > nowadays. Isn't it possible to use my 8MB compact-flash card? ehhehe
> 
> Yes, it is.   You can get IDE to compact flash adapters, and this will let 
> you boot your machine from CF without needing LinuxBIOS.
> 
> > However, I must say the price of a DoC is quite high... very comparable
> > to the cost of a pcchips motherboard, which I can find for as low as
> > 45EUR... 30 (plus shipping!) for the DoC is much...
> 
> Please tell me where to get a PC-Chips motherboard for 45 Euro.   I like the 
> sound of this.
> 
> > There is no other possible solution about this? I will have an IDE hard
> > disk in the system... perhaps it's possible to have a working LB without
> > a DoC?
> 
> You can get LinuxBIOS + etherboot into a 2 Mbit Flash chip if you can boot a 
> kernel across the network.
> 
> Regards,
> 
> Antony.
> 
> 

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