Re: Question:The internal 3 1/2 drive on the //c+

[Mitchell Spector <mitch2gs@hotmail.com>]

Lockar <lockar@nosppam.com> wrote:

>     I think I've asked this before.  What is different with either the
>disk coltroler or physical 3 1/2 drive on a Apple //c+ that would not
>let you to do bit copy.  

    The Apple IIc Plus uses a standard Apple 3.5 (800K) Sony mechanism
which is controlled by an IWM controller chip. In that sense, it is identical
to an Apple IIgs or early Macintosh up to this point.

    The difference is there is extra circuity logic between the IWM and 3.5
drive that allows a slower (1 MHz) CPU to keep up with the higher bit rate
and data flow, otherwise you'd be limited to an "intelligent" drive such as
the UniDisk 3.5. The decision to add a built-in Zip Chip accelerator in the
IIc Plus was well AFTER the special circuity was designed, so it was left 
in and used in the end, even though technically it's not necessary.

>      I remember when I got the //c+ (my second comouter when I was
>young) that you can't use the bit copy of CopyIIplus unless you used an
>external drive.  
>
>      Why is this?

    An external Apple 3.5 drive is also affected by the extra circuity logic
on the motherboard, and technically no different than the internal 3.5 
drive, unless we're talking about hooking up a UniDisk 3.5 which has its 
own logic inside the drive itself (i.e. RAM, ROM, CPU, firmware). There
shouldn't be any advantage in the software using an external Apple 3.5 
drive.

    I've never played much with Copy II Plus on my Apple IIc Plus, but 
my guess is it's not expecting an internalized 3.5 drive. Remember that
before September 1988, there was no such thing as an Apple II model
with built-in 3.5 floppy drive. Do you have Copy II Plus 9.1? (or any 
version written well after the release of the IIc Plus, say close to 1990).

Mitchell Spector