Different Mac Models.

[Timothy A. Seufert]

At 12:43 PM +0000 3/15/00, Iain Sandoe wrote:
>>
>>>To nitpick, the chip in question (the PMU) is really a power
>>>management chip which also happens to implement ADB in older models.
>>>
>>>The Sawtooth, iBook, and Pismo all use a new PMU design which is the
>>>first major revision in many years.  It probably doesn't actually
>>>have any pins dedicated to a physical ADB bus anymore, but a virtual
>>>ADB bus implemented in the PMU's firmware is quite possible.
>>
>>  Yes, that's how it's implemented: software emulation of ADB in the PMU.
>>  To my knowledge it's only in the firmware of the iBook and PowerBook PMU,
>>  not in the new iMac nor in the G4 PMU.
>
>firmware as in local (to the PMU) flash/rom...

Firmware local to the PMU.  Previous to the new PMU, the firmware was
in mask ROM, but the new PMU used in Uni-N based systems has flash so
it can be updated.  In both cases the ROM / flash is integrated into
the PMU die, separate from the main system firmware ROM/flash.

   Tim Seufert

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