Here are a couple of pictures of the 8-processor AppleCrate I.
In them you can see the simple wooden frame used to hold eight Apple //e boards.
The system is powered up, as you can see from the power LEDs and the "speaker" LEDs. (You
can also tell that I'm not a carpenter!)
Since this was initially written, I've constructed a 17-processor AppleCrate II
using a different construction methodology and Enhanced Apple //e main boards, and incorporating an integral
"master" processor so that it can be used as a self-contained unit. I've also revised the network boot
protocol so that the boot code will fit in the ROM of an Unenhanced or Enhanced Apple //e.
If you look closely, you will note that I added blinking green "send" LEDs attached beside the
cassette jacks. This is a snapshot of its appearance while it is waiting to be booted
over the network by a "master" machine.
In the second shot, you can see the little interface perfboard on the bottom, right side
that connects via NadaNet to other machines.
I originally hoped to use the board edge connectors that Apple used at burn-in to
power the boards, but discovered that different board revisions have different edge
connections, and none have all the voltages normally supplied. So I decided to use
threaded rods as power (on the bottom) and signal (on the top) busses.
I've written some articles describing AppleCrate and its use: