Re: IIgs / Duo Disk / Monitor 100 compatibility question

[spec@vax2.concordia.ca (Mitchell Spector)]

In article dempson@actrix.gen.nz (David Empson) writes...

>In theory, the IIgs will control a DuoDisk quite happily.  However,
>there is a minor hardware incompatibility between some DuoDisks and the
>IIgs motherboard.  I'm sure Nathan's FAQs will have information on this
>(I've never used a DuoDisk and rarely seen one, so I haven't made any
>notes on this).

    I believe the incompatibility has to do with daisy-chaining a
DuoDisk with other drives, using the GS's back port. It draws too
much power; this is corrected by clipping one or more of the
capacitors from the DuoDisks's analog board (it will still work
afterwards on a non-GS after the modification).

    The other incompatibility has to do with the ROM 3 motherboard.
According to Apple (and from my own personal tests) a DuoDisk will
not function at all from the backport. You either need to modify
the drive in some way (I've not seen this documented) or use the
5.25 interface card through one of the GS's internal slot.

>You might also need an adaptor cable, since I believe
>the DuoDisk has a larger connector than the UniDisk (not for any useful
>reason).

    The DB connector going to the computer end is a plain DB19 male.
Your probably thinking of the connector on that goes to the DuoDisk
itself, which is a DB25. An adapter is not required then.

>> Same question on the monitor. If memory serves me it's the Color Monitor
>> 100 and features the motorized tilt. It uses a dedicated RGB card and a
>> similar cable to the GS. Will the GS directly drive that monitor or must I
>> also install the card?
>
>If this is a digital RGB monitor that works with Apple's RGB extended
>80-column card, then it cannot be used at all on the IIgs, to my
>knowledge.

    The Monitor 100 is indeed a digital RGB display (it was sold
mainly for the Apple III, and IIe with the above mentioned card).
It actually will work on the IIgs to display a picture, but all
the color information will be wrong (not too mention you'll not
be able to display the thousands of colors the GS offers).

    By the same token, you can hook an analog AppleColor RGB in
to the Apple III, but the same problem with color will be there.
I wouldn't really recommend doing either actually, but it might
be okay for a quick diagnostic check of the computer.

>You might need a ROM upgrade for the ProFile card to get it to work in
>the IIgs, but otherwise no problem (5 MB isn't really enough to run much
>in the way of useful software on the IIgs).

    The ROM firmware upgrade for the ProFile controller is only
necessary if you want to run GS/OS (the part number of the newer
ROM is 341-0229, probably with a -B suffix on it).

    It'd be quite of silly connecting up a ProFile to a GS, you'd
practically fill it all up installing the System Software (you could
use it as a System boot "disk" mind you, and nothing else, but it
would be so slow I'm not sure it'd be worthwhile).

Mitchell Spector
spec@vax2.concordia.ca