[Coco] Fest Day 1...

[Steven Hirsch]

On Sat, 28 Mar 2009, Allen Huffman wrote:

> Some of the mystery "networking" cards I have with the CoCo 3 prototype were 
> apparently identified ... and not by someone at the Fest! Details soon (or he 
> can reply to this list with the information).

Sure, my pleasure.

Allen has pictures on his Blog of what appear to be Corvus Omninet 
interface cards; two for the CoCo and one for a TRS-80 III.

Check out:

http://en.wikipedia.org/wiki/Corvus_Systems

for a bit of background.  That article has a number of small factual 
errors (never saw a Concept monitor with a mercury tip-switch, for 
example) but should provide the gist of it.

I've been fascinated with their products for reasons only a vintage 
computer buff could appreciate:  It's the best way to showcase machines 
from that era.  How else could I have an Apple 2, Apple 3, Atari 800, IBM 
PC and a TRS-80 Mod I all working from the same hard drive?

Over the years I've accumulated a fair-to-middlin' collection of their 
hardware and software, including the oddball "Bank" tape drive which used 
continuous cartridges that worked like 8-track audio tapes - complete with 
head-stepping to change tracks - and a complete, working Concept system 
(see article) with prototype 512K memory expansion.  Doesn't seem too 
special until you consider that 48K was considered a whopping amount of 
memory in 1981.

On a technical level, Omninet was an early implementation of CSMA/CD 
protocol, where each interface on the bus is able to sense when someone 
else is "talking" and backoff for random periods of time before attempting 
re-transmission.  This was the same approach used by AT&T StarLAN and the 
original 10-Base2 ethernet.

There are a small number of Corvus buffs in the wild, and a lot of tech 
documentation and software has been duplicated and posted around the net.

Until tripping over Allen's photos, I was completely unaware that an 
interface for CoCo ever existed.  The ones I do know are are (* = I have 
it in my collection):

DEC LSI-11
DEC VT-180 (CP/M)
Xerox 820 (CP/M) *
IBM PC & XT (DOS) *
Apple II (DOS 3.3, ProDOS, GS/OS, Pascal, CP/M) *
Apple /// (SOS) *
Atari 800 *
Macintosh
TRS-80 Model I *
TRS-80 Model II/III
CoCo 3

Steve


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