[ih] "network unix"

[Bernie Cosell]

One amusing entry in this is the MBB, which had 20-bit words in two 
ten-bit bytes.  Perhaps someone on this list is familiar with the 
hardware that BBN developed and how things worked on it [I think it had a 
special mode where it transferred bytes from the internet into the 
low-eight bytes of consecutive words, and there was some magic I don't 
remember that allowed us to treat them as a 16-bit number when necessary.

I don't remember much about it as the IMP replacement.  I worked on the 
project to bring Unix up on it.  Carl Howe wrote the microcode, Al Nemeth 
was poring over the Unix kernel figuring out what needed tweaking, and I 
wrote the compiler.  AT first a cross compiler from our PDP-10 to the 
MBB.  Handling constants and bit masks was very,er, uh, interesting, but 
we compiled the "standard" Unix kernal and utilities and between the 
three of us had to make it work.  It was intended as an inexpensive 
*temporarly* replacement for the 11/70, but was _so_ fast [Al did an 
amazing job of finding ways that the compiler could optimize the kernel 
code, Carl added new instructions and such as required and I got the 
thing to compile using the new tricks] that it survived for YEARS.

The magic day was when I compiled the compiler with itself and put it on 
the MBB.  and then had the system compile its *OWN* kernel.  AT that 
point the MBB was a self-sufficient Unix system and someone else will 
have to tell the story -- I moved on to other projects.   But it was a 
quite potent and [at BBN] common "network Unix" node.

  /Bernie\

-- 
Bernie Cosell                     Fantasy Farm Fibers
mailto:bernie at fantasyfarm.com     Pearisburg, VA
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