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

[Vint Cerf]

At some point, the BBN Cxx machines also offered an X.25 interface because
around 1983, I was using them to build MCI Mail and the network interfaces
were X.25 vs BBN 1822, for example.

v


On Sat, Sep 27, 2025 at 1:00 AM Noel Chiappa via Internet-history <
internet-history at elists.isoc.org> wrote:

>     > From: Jorge Amodio
>
>     > TIP (Terminal Interface Processor) ~= TAC (Terminal Access
> Controller)
>
> The biggest difference between the two was that the TIP used the older
> Network Control Protocol protocol family, whereas the TAC was also able to
> use the newer TCP/IP family. (I see from "Getting Started Computing at the
> AI
> Lab":
>
>   https://dspace.mit.edu/bitstream/handle/1721.1/41180/AI_WP_235.pdf
>
> that a TAC user could switch back and forth - pg. 17 of the PDF.)
>
> The TIP also included IMP functionality, and TIPs could be ARPANET nodes;
> the
> 'MIT-TIP' machine used to be one of the two IMPs at MIT: IMP #44, to be
> exact.
> Not so for TACs.
>
> Does anyone remember how TACs which used to be TIPs connected to the
> network,
> though? (I mean using what hardware?) I see that the host 'MIT-TIP' used to
> be 2/44; i.e. host 2 on IMP 44. That machine would have conncted to the
> rest
> of the ARPANET via phone lines (so through a modem port). However in its
> later 'MIT-TAC' incarnation, it was 10.2.0.77; i.e. it was connected to IMP
> 77 - I would assume via an 1822 port? Did ex-TIP machines use one of their
> one-time 1822 'IMP' ports as a 'host' 1822 port?
>
> I should know that, because I was the MIT 'IMP liaison', and I do remember
> a
> bunch of events with them (e.g. the move of MIT-MC, which involved
> converting
> an LH port on a C/30 IMP to a DH), but I have no memory of the switch to
> the
> C/30 IMPs.
>
> Also, were there any TACs which were not one-time TIPs? If so, what was the
> hardware base? Maybe a C/30 with a multiple serial line controller?
>
>         Noel
> --
> Internet-history mailing list
> Internet-history at elists.isoc.org
> https://elists.isoc.org/mailman/listinfo/internet-history
> -
> Unsubscribe:
> https://app.smartsheet.com/b/form/9b6ef0621638436ab0a9b23cb0668b0b?The%20list%20to%20be%20unsubscribed%20from=Internet-history
>


-- 
Please send any postal/overnight deliveries to:
Vint Cerf
Google, LLC
1900 Reston Metro Plaza, 16th Floor
Reston, VA 20190
+1 (571) 213 1346


until further notice