[rescue] AT&T 3b1 Starlan software

[Jonathan C. Patschke]

On Thu, 12 Feb 2003, Scott Newell wrote:
> What happens if someone moves a card from one slot to another?  (I've
> never messed with the Apple II, and I've always wondered how software
> could figure out which interrupt lines and memory spaces to use when
> cards got shuffled around.)

Simple--the lines are hardwired to particular slots.  IIRC, moving a
device from one slot to the next didn't affect its operation, other than
bootable devices would be queried in order of decreasing slot-ID.  That
is, the system would attempt to boot from the device in slot 7, then 6,
then 5, etc.

When you set up your software, it would ask you where some devices were.
For example, floppy controllers typically lived in slot 6.  Some
software assumed this, but most software would ask, espeically if it
didn't see a floppy controller there.  The same thing went with the
serial card (which lived in 3 or 4, I think) for communications
software.

Now, this sounds cumbersome in this age of plug-and-play, but it's a lot
easier to look at the rear of a computer and say "Hm, the wire to the
disk-thingie plugs into the slot next to the number 6" than remembering
IRQ + DMA + Memory address like PCs made you do all the way into the mid
90s, and more flexible than the PC way of "devices available at boot
time -MUST- be at IRQ/DMA/Memory such-and-such".

The most frustrating thing about all this is that the IBM PC won the
horsepower race for desktop computers in the day (unless you wanted to
hand Sun or SGI $$$$$).  It -could- have been a wonderfully elegant
device, but the design was horrific.

-- 
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