booting from floppy.

[Chris Jankowski]

In article <209 at trux.UUCP> car at trux.UUCP (Chris Rende) writes:
> In article <76854 at pyramid.pyramid.com>, csg at pyramid.pyramid.com (Carl S. Gutekunst) writes:
>> >Who ever heard of booting from Floppy?
>> 
>> What would you suggest? You can't do the IMPL from hard disk, unless we had
>> a dedicated disk just for the SSP. DEC used an HP catridge, although those
>> proved to be more expensive and less reliable than a simple 5" floppy. The
>> tape is also inappropriate for automatic dumping of hardware diagnostics.
>
> Does the boot process require that floppy to be present?
>
> If so it's a scary thought. A chain is only as strong as its weakest link.
> I'd be very uncomfortable knowing that my mightly mega-$$$$$ Unix box could
> be rendered useless by a missing or blown 50 cent floppy.

I cannot agree with this line of reasoning.

Aren't you afraid that your kilo-$$$$ car may be rendered useless by a failure
of a 50 cent valve in each of your tyres? And there are four of them to blow 
out.  (:-)). Would you prefer to have zilion parts super duper self regulating
self propelled auto-inflating pressure controller instead?

Lets look at the task first and then discuss options you may have.

The task is in principle to download some tens of kB to SSP (this is
a separate support processor) and you cannot use disks yet as the microcode
of the disk controller has not been loaded yet.
You also need to store some error messages SSP may have about hardware
problems it detected in the system.

So you need a read/write device of at least about 200 KB capacity which
will not loose its contents when power goes off. It also should have 
cheap and easily transportable media - microcode gets upgraded and
error messages have to be analysed in the vendor premises.

Well, what would you propose? 
Core memory, buble memory - what about cost?
Take-away 20MB disk - cost, what about just posting it - did you see how
mail is handled.
Battery backed RAM - may look reasonable - we shall see - MIS server is to
use it as far as I know. But it is still more expensive than floppy.
Another separate computer with its own I/O. It's no joke. I know of 
at least one UNIX machine (NP1) which used a fully equipped AT class
clone with 20MB drive exactly for this purpose. What is likely to fail
first a floppy or the whole AT with hard disk, own memory, disk controller, 
video controller and colour monitor? And how do you distribute 
microcode patches then? 

Actually floppy stands up quite well. If the floppy itself is broken,
you can't boot and you try another one. Once the system is up and running
SSP writes only some hardware error messages (if any) on the floppy and
even if the floppy wears down sitting in the drive forever - who cares
about those unreadable cryptic error messages.

      -m-------   Chris Jankowski - Senior Systems Engineer chris at yarra.oz{.au}
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