DIYbanter - View Single Post - Adding missing SATA connectors to motherboard

krw[_4_]

In article t,
_ says...
krw wrote:

On Mon, 12 Jan 2009 23:07:02 -0500, kony wrote:

Come to think of it, there was very little that had more
than 2 layers before '80, so if that is where your supposed
experience comes from, suddenly it all starts to make sense.

DimBulb is certainly AlwaysWrong, but the above is simply bull****.
Perhaps in your little corner of the world you were still using
phenolic substrates too but others had moved on long before. We were
using upwards of a hundred layers (96, IIRC) on system backplanes and
easily eight layers (4P-4S) on plug-in cards well before '80 (the
latter were old hat when I started in '74). I haven't done anyting as
simple as two layers since college projects, and that was limited by
our wierd method (sides were cut individually on a lathe then
laminated).

My first hands-on direct exposure to large multilayer real estate was
a 12 layer Control Data Terminal Systems CPU board which held about 400
MSI devices densely packed, made in 1970.

IBM mainframes. Our standard boards were 10 layer PWB + wirewrap
overflow and customization in the '60s. The plug-in cards
(nominally 18 per board) were usually 8 layer. Four were needed to
power the ECL. In the late '70s things shifted to 100 (then 121)
chip MCMs on huge boards (~3'x3', IIRC). These pretty much went
away with the ECL processors. CMOS packed more into the chips
without increasing the board wiring density much. The number of
layers on the MCM boards was dictated by timing and impedance
control required as much as density.