[ih] NCP and TCP implementations

[Steve Crocker]

The TAC was an extension of the IMP.  The original IMP was built on the
Honeywell 516 (and later 316) platform, which was a 16 bit twos complement
computer.  I assume Hinden's reference to 15-bit arithmetic reflected the
fact that the arithmetic was signed.

Steve


On Tue, Mar 10, 2020 at 1:20 PM Leo Vegoda via Internet-history <
internet-history at elists.isoc.org> wrote:

> On Tue, Mar 10, 2020 at 9:02 AM Bob Hinden via Internet-history
> <internet-history at elists.isoc.org> wrote:
>
> [...]
>
> > I later did a TCP implementation for the TAC in H-316 assembly language.
> > Was lots of fun doing 32-bit segment calculations on a machine with
> 15-bit arithmetic.
>
> Do you know why the designers of the TAC chose 15-bit arithmetic for it?
>
> Thanks,
>
> Leo
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