Remind me the purpose/function of daisy chaining floppy drives

[Rick Dangerous]

I know this is a dumb question, and i'm sure a i'll remember after the first post.  But how does a functioning daisy chain work/function best again?

So the primary disk drive is plugged into the computer, and the second floppy drive is plugged into the first...but when you fire up the computer it only reads off the first correct?  If there was a program with a disk two, would you have to hit a button or key sequence for it to run the second disk.

For example on an apple II, IIe, c, or gs.  If anyone is up for it please remind me how best to utilize the second daisy chained drive.

I guess on the GS, or computers with a GUI, both discs are visible and you can choose to run either one, so what about earlier Mac Dos systems?

Thanks in advance!

 

[Rick Dangerous]

Bueller?  

Amy succinct explanations are welcome.

 

[david__schmidt]

You asked a bunch of different things, with different answers.  A daisy chain containing 5-1/4" drive(s) must have the 5-1/4" drive(s) at the end.  That is the most important rule.  On a GS, for example - all "slots" are virtual when it comes to plugging in drives to the back.  Daisy chained drives will take up the virtual slot and drive numbers based on their type.  Consider this chain:

GS->3-1/2"->5-1/4"

The 3-1/2" drive will occupy Slot 5, drive 1

The 5-1/4" drive will occupy Slot 6, drive 1 

If you chain other things in between, like another 3-1/2":

GS->3-1/2"->3-1/2"->5-1/4"

Then you get the 3-1/2" drives in Slot 5, drive 1 and Slot 5, drive 2

The 5-1/4" drive will (still) occupy Slot 6, drive 1

An Apple II will only ever boot from drive 1 in any particular slot.

 

[Juror22]

That is good information - it helped me, since I had been wondering about Apple ][ booting, after getting a couple of them last year and testing the drives.  I thought that this might be the case, but had not looked into a definitive answer.

 

[Gorgonops]

If there was a program with a disk two, would you have to hit a button or key sequence for it to run the second disk.

As noted, those machines will only boot off the first drive in a given slot. If after booting DOS you want to load a piece of software off a disk inserted into the second drive there are commands to switch which drive an action happens on. (These are somewhat more straightforward in Prodos than they are under 3.3.) Here's a short Apple DOS FAQ.

Realistically speaking, most Apple II software expects to reside on the first drive and will just use the second drive to store user data. (We're talking productivity software, of course, games usually don't use it at all.)

 

[Gorgonops]

An Apple II will only ever boot from drive 1 in any particular slot.

Actually, just for completeness' sake, I'll note that technically the original version of the Apple IIc had a mostly useless ROM quirk that allowed you to force it to boot from an external 5 1/4" drive instead of the internal one. The reason it was mostly useless is because the "PR#7" alias was strictly ROM-level, in reality the external drive was physically disk #2 in Slot #6. Therefore almost all self-booting software and non-patched DOS 3.3 would get lost and confused once it got past the ROM bootstrap by the disk drive not *really* being where it expected it.

It's not at all clear why this feature was in the ROM at all. An emergency workaround in case the internal drive failed?

 

[Rick Dangerous]

Super helpful!  I will be referencing this thread for a while until it is all fully ingrained.  I knew most of this at one point but the 5 1/4 needed to be at the end of a chain I did not...so super helpful thanks to you both.