DCAWD.com

Introduction

In 2004 I built the first AppleCrate, an 8-board system, as an inexpensive, easy to program vehicle for experiments in parallel programming—a kind of "blade server" for the Apple II, if you will! AppleCrate I (at the time I didn't realize that it was number "I" was great fun, and it enabled some very interesting experiments, but over time I discovered some of its shortcomings.

First and foremost, since the boards were supported by only two edges and not clamped in place, it was relatively fragile and hard to transport. Second, I had come across situations in which more than 8 slave processors would have been useful. Third, my arrangement for collecting audio signals synthesized by the slaves was quite makeshift and delivered sound with lots of digital "hash" as background noise. And finally, the original AppleCrate made no provision for plugging I/O cards into any of its boards, so it had to be hosted by a separate Apple II, adding to the problem of transporting it for demonstrations.

The AppleCrate II is designed to be significantly improved in all of the areas that were problems for the AppleCrate I.

Description

The AppleCrate II is made from 17 Enhanced Apple //e main boards. (Fifteen of these boards were obtained in the same eBay auction that netted the eight unenhanced boards for the original AppleCrate.) Because they are enhanced ROMs, the original NadaNet boot ROM code would not fit and a new boot protocol had to be developed, as described below.