[rescue] AT&T 3b1 Starlan software

[Jonathan C. Patschke]

On Thu, 13 Feb 2003, Scott Newell wrote:

> OK, this is what I wanted to know.  If software assumes that the floppy is
> always slot 6 and you move it, you're hosed, correct?  That's the big
> drawback that I can see.  (And I realize it's only a problem for poorly
> written code.)  Did they make allowances for cards that require more than
> one interrupt line?

Why would a card need more than one interrupt line?  The card itself
should only need one line to the CPU to say "Hey!  I have data!".  The
notion of needing, for example, one IRQ per serial port is wasteful.
It's not hard at all to multiplex interrupts for a multiport card.  The
CPU can only service one interrupt at a time, so you really don't gain
anything by having the serparate IRQs.

> Does each slot have X amount of memory space allocated to it?  Seems to me
> the simple backplane has an advantage if you've got cards that require
> almost no memory space, and some cards that require a large chunk.

I'm not really clear on how the Apple ][ handled that.  But, yeah, that
could be a problem.

-- 
Jonathan Patschke  *)  "It's not about who's right and who's wrong...
Thorndale, TX      (*   it's about who works for the government and who
                   *)   doesn't."                        --Dave McGuire