'motherboard' etymology

John Willis chocolatejollis38 at gmail.com
Mon Feb 29 11:21:51 CST 2016

> Computers existed way before 1980, and had many boards plugged into
> wire-wrapped backplanes or motherboards.    I'm guessing the terminology
> was company-specific.  IBM had their own name for EVERYTHING, for
> instance.  They did NOT use the term motherboard, as far as I know.  The
> SMS systems like 709x, 1401, etc. had totally passive backplanes.  The SLT
> systems (System/360, 1130/1800, etc.) had passive backplanes, but the local
> interconnect was done mostly with etched traces on multilayer PC boards,
> which also distributed power to the cards.  They just called these
> backplane sections "boards" and the SLT circuit boards that plugged into
> them were "cards".  Not sure where I first saw the term motherboard, or if
> it really implied it had substantial active circuitry on it.
FWIW, the IBM term for "motherboard" was "planar", at least in the era of
the PC, PC/XT, PC/AT, etc.
The first computer to which I had access was my father's 5150 in
approximately 1984; I remember the
machine came with dual floppy drives and a 64K system planar with an Intel
8088. At some point, a
technician came out and put in a different planar with 256K on-board, added
an additional 256K via
expansion board, and configured it with a 30MB half-height Winchester drive
and controller. This second
planar had an AMD D8088 at the same 4.77MHz speed as the original.

Having this machine handed down to me in about 1991 sparked my interest in
programming; many hours
of BASICA silliness and PC-DOS batch file frustration followed.

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