25 May
2007
25 May
'07
11:18 p.m.
The standard floppy controller can drive up to four floppies, two
internal and two external. And the motherboards of these machines
have dip switches that allow you to tell them how many drives are
connected. But those switches are just a simple count of drives, not
which chain the drives are connected to.
Normally I see these machines with two internal floppies, and nothing
else. On the 5160 I have here in the office I am about to add an
external floppy using the external connector on the floppy controller;
the machine has a single drive installed internally now. How does the
BIOS handle this situation? If I tell it that there are 2 drives will
it try to figure out that one is internal and one is external? Do I
need device driver help, or is this something the BIOS tries to
handle? Is there something on the controller card I am supposed to do
to tell it how the drives are connected/organized?
The BIAS is, as usual, brain-dead. It assumes you'll fit both internal
drives before adding external ones. So if you set it for 2 or more drives
and only have one intenral drive, it'll give an error at boot-up
Moreover, if you have 3 or 4 drives, they will be asseigned the letters
A: B: C; (and D:) by MS-DOS, putting the first hard disk partition at E:.
A _very_ large number of installation programs get confused by this.
My suggestion is to set the DIP switches to say you have one floppy
drive. And then (asuming you're running a late-enough MS-DOS) to use
DRIVER.SYS to operate the external drives. If you do that, the internal
drive will be A: _and B: (as it would be on a single-drive machine), your
hard dirve partitions will start at C:, and your exernal drive(s) will
have letters assigned after the last hard drive partition.
-tony