[ih] NCP and TCP implementations

[Alex McKenzie]

 The key driver was that the TIP be managed as part of the network, rather than as part of a user organization.  That meant that BBN followed the same rules for the TIP that they did for the IMP, which included "no rotating storage", which in those days was quite unreliable in a MTBF sense.  And we wanted it to be in the same box as the IMP, sharing a processor, so it had to exist in 16K of 16-bit words.  Other approaches, like ANTS and ELF, ran in separate boxes and were run by user organizations, so more buffers and more code for specialized I/O devices were possible.  ARPA supported, one way or another, all of the TIP, ANTS, and ELF.
Cheers,Alex McKenzie (BBN 1967-96)

    On Tuesday, March 10, 2020, 2:20:35 PM EDT, Leo Vegoda via Internet-history <internet-history at elists.isoc.org> wrote:  
 
 On Tue, Mar 10, 2020 at 11:07 AM Steve Crocker via Internet-history
<internet-history at elists.isoc.org> wrote:
>
> To create the TIP, a second bank of memory was added to the 316 and some
> interrupts and modes were added to enable switching back and forth between
> banks.  It was a bit of a kludge with some unexpected interactions.  The
> BBN crew finally sorted out the details and wrote a delightful titled "It's
> Amazing That it Works at all."

Am I right in inferring that the key driver behind the design decision
was cost rather than elegance?

Thanks,

Leo
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