

Ask HN: In Apple parlance, why is the motherboard called the logic board? - kunai

Title says all.
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marssaxman
On the original Macintosh, there were two circuit boards: the "analog board"
contained the power supply and CRT driver, while the "logic board" held the
microprocessor and all the digital logic.

At the time, "motherboard" was a more general term, describing any arrangement
where "daughterboards" plugged into sockets on a "motherboard".

~~~
Someone
I think you mean _less_ general. A motherboard must allow daughter boards to
be plugged in.

On the other hand,
[http://www.imsai.net/download/IEEE_696_1983.pdf](http://www.imsai.net/download/IEEE_696_1983.pdf)
uses it for he board that generates the clock signal:

 _" The memory write strobe, MWRT, shall be generated somewhere in the system.
It has traditionally been generated by front-panel type devices, but is
optionally generated by permanent masters or mother boards in systems without
front panels"_

In my memory, however, the term 'motherboard' originated with the PC and is
restricted to the PC.

For example, I can't find the term in Wikipedia's article on the S-100 bus
([http://en.wikipedia.org/wiki/S-100_bus](http://en.wikipedia.org/wiki/S-100_bus)),
the Apple II reference manual
([http://ia600602.us.archive.org/19/items/applerefjan78/appleI...](http://ia600602.us.archive.org/19/items/applerefjan78/appleIIrefjan78.pdf)),
or the Macintoh II service manual
([http://tim.id.au/laptops/apple/legacy/macintosh_ii.iix.iifx....](http://tim.id.au/laptops/apple/legacy/macintosh_ii.iix.iifx.pdf))

They use terms 'processor board', 'board', and 'logic board'.

~~~
marssaxman
I mean that a PC motherboard is a specific type of "mother board", which is a
board into which one plugs "daughter boards", aka expansion cards. I have
vague recollections of this terminology being used in the late '80s to
describe machines with upgradeable processors, and have thus imagined that
this is where the modern sense of "motherboard" comes from. But it was 25
years ago or more, so my memory may not be accurate.

------
blakdawg
Older Macs with built-in monitors had two main circuit boards - a video board
and a "logic" board with the CPU, RAM, etc.

------
daenney
Because Apple is our mother. She is so much she can hardly be encompassed in
something simple as a board with a bunch of chips. But all the logic, the
brainpower of her children, is located on such a board. Therefor it's only
logical this be called a logic board.

