With the first meeting in 3/5/1975, the
Homebrew Computer Club took place in Gordon French's garage in
Menlo Park, California.
It was around the time when the first 8 bit microprocessors were introduced, like Intel's 8008, MOS 6502, and the Motorola 6800. These could finally give birth to the first affordable home computers, the so called third generation computers.
It seems that in this first meeting, the hype was around
the Altair 8800, a computer kit described in the January edition of Popular Electronics.
Steve Wozniak was an attendant in this first meeting. In the following year he presented at the club, with Steve Jobs, the Apple I computer.
The second meeting found 75 people in attendance, and was held at Aristidero School. A year later, that number had grown tenfold.
Some of the attendants to the original meeting reunited at the 26th anniversary of the club, which can be seen at:
http://www.bambi.net/bob/homebrew_reunion_article.txt
(lots of info on the first meeting there)