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Re: remapping capslock key on ibook

Ted Lemon <email@hidden> wrote:

I spoke too soon - sorry about that. It turns out that you are right that
the hack doesn't work on the iBook keyboard. Sigh. I don't know whether
or not the iBook keyboard is ADB

All PowerBook / iBook keyboards are. The trackpads too.

- it seems kind of stupid to have an ADB
chipset on the motherboard when you could just have a UDB chipset -

The devil is in the details. It's really not stupid at all.

An external USB or ADB input device contains a dedicated chip that interprets raw sensor data (keyboard matrix scanning, etc.). Not so for the PowerBook internal peripherals. Instead, they are connected directly to the PMU chip, a multifunction custom glue IC that Apple puts in all Macs (the PMU is also known as "Cuda" in some vintages of desktop Macs).

When Macs still had ADB ports, another of the PMU's functions was to be the ADB controller. The key is that, as the ADB controller, it could make the internal input devices appear to be ADB devices as far as the OS was concerned, even though they had no physical connection to the ADB bus. This was a simple function to do in the PMU's firmware (the PMU is a microcontroller), and prevented the need for special drivers for PowerBook input devices.

In the post ADB age, the physical ADB controller is gone from the PMU, but it was simplest for Apple to retain the model of presenting the keyboard and trackpad as virtual ADB devices. It costs Apple basically nothing to build, and has been battle tested for the better part of a decade, so I wouldn't expect it to go away any time soon. :)
--
Tim Seufert
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