[ih] when did ARPANET -TIPs become known as -TACs

[James J Dempsey]

I am not the authority on this, but I'm pretty sure that TIPs did NCP and
TACs did TCP/IP.  If I'm right about that, the TIPs would have been obsolete
after the Jan 1 1983 flag day.  It may very well be that all TACs were
MBB-based.  TIP commands specified hosts as something like 2/4 -- host 4 on
imp 2 (IIRC) while TACs used dotted quad we're familiar with today.  10.0.2.4.

On 9/28/25 10:08, Jack Haverty via Internet-history wrote:
> Similarly, a C/70 was a Unix minicomputer also built on an MBB, but with
> an interface to disk storage and probably more RAM.? The MBB microcode
> used for a C/70 was optimized for code written in the C language, which
> was the language used by the Unix OS.

The C/70 had a couple issues that made it less than ideal competition for
DEC.  First, the word size was 20-bits, two 10-bit bytes, something that
made network programming a bit challenging.

Second, the C/70 had up to 2MB of RAM.  We certainly had them supporting
perhaps half a dozen to maybe ten developers to each system.  The problem
was that while the C/70 might have been great competition to the PDP-11, DEC
introduced the VAX at about the same time with virtual memory which was a
game changer.  And the VAX had 32-bit words which were much more natural for
network programming.

> There was also a C/60, but I can't remember what it did.....

My memory is that the C/60 was *exactly* the same as a C/70, with a slower
clock chip and a lower price.  There was even an "upgrade" customers could
buy to upgrade the machine to a C/70.  (The upgrade, of course, was a faster
clock crystal.)

One of my favorite C/70 stories was this:  The C/70 rack had two winchester
drives at the bottom which pulled out like drawers.  I believe they were
originally 80MB each.  The problem was that if you pulled both drawers out
at the same time, the rack would come tumbling down on top of you!  To fix
that, there was an ECO (I think called "ECO-PB") which was essentially two
lead bricks you would put in the rear of base of rack which would offset the
weight of the open disks and keep it from tipping!

One of the C/70s big advantages was that it came with UNIX installed and
that UNIX was actualy supported by BBN.  Back in those days, you got your
hands on a UNIX license and got some tapes from someone, but if you had
problems, there was no one to call to support your UNIX installation.  DEC
certainly wasn't going to do it, nor was Berkeley.  You can see a button
from a trade show in the upper left of this photo proudly proclaiming that
BBN-UNIX was supported by BBN:
https://serenity.jjd.com/Images/bbn-buttons.jpg

The BBN-UNIX was a pretty nice UNIX too.  It was mostly V7-based, if I
remember correctly, but with BBN's TCP network code and IPC mechanisms
(named pipes) and a bunch of BSD tools. csh was there as was tcsh -- with
cmd line editing -- and job control.

The 2MB address space was a big limitation.  I remember Gosling's Emacs took
a minute or two to start.  I would start it in the morning and leave it
running all day to avoid having to pay the start time penalty.

                       --Jim--