Subject: Re: Oh, well. / ADB controllers
To: None <>
From: Brad "ADB Guy" Grantham <>
List: macbsd-general
Date: 07/18/1994 23:40:06
Allen Briggs writes:
> Brad should probably address this--he knows a bit more than I do about
> the adb situation.
> > Why don't we collect some data to determine the scope of the diversity of
> > ADB implementations and the scope of the problem ?
> As far as I can tell, there are two basic adb systems.  There is the old
> MacII-class adb system, and then there is the 68HC05-based.

This is my impression as well.  The problem is not that I have to
figure out the 6805, but the 6805 is masked with a ROM that controls the
ADB per instructions from the VIA.  That behavior is difficult to
glean from the chip # or any documentation that Mitsubishi can provide
about their 6805.  Apple masks their 6805s with their own ROMS, and so it
might as well be a 68040.  However, I have a IIvx, as Allen says, and
hopefully I can soon get to work on IIvx ADB (as soon as I get my cheap-o
VGA monitor working).

> but I'm pretty sure that [ the ADB microcontroller ] will be
> programmed to be as much like the older system as possible--just because
> the MacOS is in the same boat we are--trying to run on all these systems.
> Heck, I wouldn't be surprised if the 68HC05 was in the PowerMacs.
> However, Apple might've buried it deep in the core of some large IC
> that has nothing but an Apple (c) on it...  ;-)

My hope is that if I can get something working on two of the 6805-
based Macs, that it will work on the rest by interpolation.  (But I'm
not investing my life savings in "MacBSD Consulting, Inc" yet.)

> Also, as far as I can tell, you are right on the money that this chip
> is in charge of power management on the platforms that have it.

This is going to be the more difficult part of making ADB work on the
PowerBooks.  I'll say no more about it, since it seems that I repeat 
this posting every month or so, and I'm sure I'm sounding like a broken

 '1' means a BLACK pixel, '1' means button UP, what will Apple think of next?
Brad Grantham, >+------+< Happily slaved to NetBSD/Mac68k!
	I thought I would have to go without dinner tonight until I
       remembered the container of chocolate frosting in the fridge!