Talk:Apple Desktop Bus

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Powerbooks[edit]

"No machines being built today currently use ADB." Actually, at least the Titanium Powerbooks (2002-3) still used ADB for the internal trackpad, and I'm pretty sure the Aluminum Powerbooks and iBooks still do as well. Anyone have one of these that can do a verbose boot to check? -- Kaszeta 15:02, 20 Oct 2004 (UTC)

ADB trackpads were used until 2005. The entire line switched to USB with the introduction of the new two-finger scrolling trackpads. Binary 20:26, 14 April 2006 (UTC)

Keyboards' default address[edit]

"For instance, all keyboards were set to $2, and all mice to $3."

"Given that all keyboards were on $3..."

Clarification, please? --Ntg 02:56, 16 Jan 2005 (UTC)-ntg--4.35.128.173 02:44, 16 Jan 2005 (UTC)


The old Apple documentation used the dollar sign ($) to indicate hexadecimal (base 16) numbers (see the entry on Hexadecimal). I believe the current programming convention is to use "0x" as the prefix for hex numbers. The phrase in question is indicating the default addresses ADB assigned to different devices. Hope this helps. -- K Cundiff —Preceding unsigned comment added by 65.197.74.25 (talk) 21:34, 28 February 2006

The above comment is more than four years old by now, and the article text has changed; but just to avoid potential confusion, a keyboard's default address would be $2 and nothing else. This document from Apple states that the default device ID for "encoded devices" (i.e. keyboards) is $2. ID $3 is "relative-position devices" (mice, trackballs). -- magetoo 10:48, 15 June 2009 (UTC)

Speculation[edit]

To quote the article "As a result, the system was not hot swappable, although this could have been implemented very easily using the PSW had they thought about this case" - what exactly is the evidence that this possibility was not considered? ThomasHarte 15:35, 19 November 2005 (UTC)

Adding to this speculation the Apple Developer Note for the Macintosh PowerBook G3 Series[1] computer (commonly called the Wallstreet) states:

"Unlike earlier ADB-equipped computers, the Wall Street computers allow the user to unplug and replace ADB devices while the computer is operating" (p 49)

suggesting that in the latter implimentations of ADB this issue was resolved. Does anyone have more information on this? --scott 05:24, 17 June 2006 (UTC)

It's not clear from this quote if the change was to allow this to be done safely, or whether the machine actually noticed these changes and did a reset. I was hoping there would be more information in the dox, but you pretty much quoted the entire section! Maury 23:52, 22 December 2006 (UTC)

USB is also still not all that safe to put in when a system is active. —The preceding unsigned comment was added by 82.171.59.199 (talkcontribs) 16:10, 22 December 2006 (UTC-7)

no plug is safe to plug-in while a system is running technically speaking, as it will cause static. (there is always a potential of frying a controller chip) Markthemac (talk) 22:25, 4 March 2010 (UTC)

Similarity to S-Video connections[edit]

  • Should the similar appearance of s-video cables be mentioned in this article? --DangApricot 00:55, 27 November 2006 (UTC)
Well the ADB is an s-video connector, so... yeah. Maury 23:49, 22 December 2006 (UTC)
I actually needed an S-Video Cable one time when i didn't have one, and it worked very near perfectly (image was a tad blurry)173.48.62.136 (talk) 11:24, 20 August 2009 (UTC)

that's right they are S-Video compatible, it always was a cheap and easy plug to produce on a mass scale. Markthemac (talk) 22:30, 4 March 2010 (UTC)

Clarification of ADB status[edit]

From the article:

but up to February 2005, PowerBooks and iBooks still used the simple ADB protocol in the internal interface with the built-in keyboard and touchpad. The internal connection for the trackpads has now been changed to USB.

This seems to imply that internal keyboards still use the ADB protocol. Is that actually the case, or did both keyboard and trackpads switch over to USB? —lensovettalk – 21:06, 8 June 2008 (UTC)

The keyboard became USB in October 2005. [2]. Really, calling any internal PowerBook devices ADB is a little misleading. The keyboard and trackpad would connect to a small microcontroller, which in turn connected to the southbridge (in earlier models, that controller essentially was the southbridge). That microcontroller emulated an ADB interface using a few of its interface registers, allowing the existing mouse driver to be reused. So there was no ADB signaling or ADB bus, just ADB emulation. Potatoswatter (talk) 22:11, 8 June 2008 (UTC)

that way apple saved cost to write a new driver for every single keyboard type, USB was a pretty bad standard for keyboards when Apple first started using it (USB was Aka Unused Serial Bus, apple hacked around an unused standard to get a unified keyboard driver functional which also worked on older non-usb hardware) Markthemac (talk) 22:35, 4 March 2010 (UTC)

Confusing paragraph[edit]

Quoting a paragraph that I find confusing:

Most serial digital interfaces use a separate clock pin to signal the arrival of individual bits of data. As ADB was designed to be low-cost, Wozniak recognized that a single wire had enough bandwidth to carry both signals at the required data rate. Moreover it was economical to decode the clock and data and use cheaper cables.

What does this even mean? "a single wire had enough bandwidth"? What does bandwidth mean in the context of a clock signal? What bandwidth does a wire have? (What is the airspeed of an unladen swallow?) What the heck does "[decoding] the clock and data" mean here?

I suggest it should read something like "Wozniak decided that a separate wire for a clock signal was not necessary, and it made economical sense to leave it out". And if someone knows the actual details it could be added to the "communication" section. -- magetoo 11:05, 15 June 2009 (UTC)

The more I read the paragraph, the more it looked like gibberish, so I rewrote it. Does it need more details or is it fine as it is now? You could argue that one would want discuss why other busses have a clock signal when ADB could do without, or when it is appropriate to leave it out, but that can quickly get pretty technical and hard to read... -- magetoo 11:20, 15 June 2009 (UTC)

Bandwidth (signal processing) is the range of frequencies found in a signal. Bandwidth of a wire (or other signal carrier) may be considered the range of frequencies that pass though it. The process of decoding signals from a carrier involves separating the frequencies. You could read the Wiki article on the confusing term… but I think your rewrite may be a better baseline for adding details. Potatoswatter (talk) 16:37, 16 June 2009 (UTC)

I get what you're saying (no, really!) but it just seems like a really weird way to think about it, like trying to describe Morse code in terms of separating out a "clock" signal and a "data" signal when dits and dahs is such an obvious way of thinking about it... Well, too much talk page space already spent on this tiny detail, it'll get lost in a rewrite sooner or later anyway. -- magetoo 20:54, 16 June 2009 (UTC)