[ih] Question re rate of growth of the Arpanet

[Tony Patti]

Bell 303 modem (suffix letter "C"): 50 kb/s synchronous, in a cabinet of size 24 inches high x 24 inches wide x 12 inches deep.

See https://bitsavers.trailing-edge.com/communications/westernElectric/modems/303_Wideband_Data_Stations_Technical_Reference_Aug66.pdf (especially PDF pages 7 and 8).

Tony Patti
(ARPAnet NIC IDENT “TP4”)

-----Original Message-----
From: Internet-history <internet-history-bounces at elists.isoc.org> On Behalf Of Vint Cerf via Internet-history
Sent: Monday, April 21, 2025 2:11 PM
To: the keyboard of geoff goodfellow <geoff at iconia.com>
Cc: Internet-history <internet-history at elists.isoc.org>
Subject: Re: [ih] Question re rate of growth of the Arpanet

Best you could do with 12 3KHz bonded channels on a Bell 303 modem

V

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




On Mon, Apr 21, 2025, 14:09 the keyboard of geoff goodfellow via Internet-history <internet-history at elists.isoc.org> wrote:

> steve, can you elucidate any history with respect to how/why the speed 
> of
> 50 kb/s was chosen for the ARPANET lines?  were there great speeds 
> available then?
>
> yours truly kinda (perhaps mistakenly) recalls these 50 kb/s "wideband 
> circuits of the day" were primarily used for linking tv broadcast 
> affiliate stations to/with their motherships (cbs, nbc, abc, ...)?
>
> geoff
>
> On Mon, Apr 21, 2025 at 7:26 AM Steve Crocker via Internet-history < 
> internet-history at elists.isoc.org> wrote:
>
> > Thanks for the pointer to RFC 597.
> >
> > As I looked at it, an aspect I hadn't considered before came to mind.
> >
> > Installation of an IMP required provisioning 50 kb/s lines to two or
> three
> > other points.  In the early days, we installed roughly a new IMP 
> > once a month.  (The lead time for ordering 50 kb/s lines from AT&T 
> > was NINE
> > months.)
> >
> > Once an IMP was installed, new hosts could be added to the IMP as 
> > quickly as the site could build or obtain the host-IMP interface and 
> > write or obtain the software for their operating system.
> >
> > If anyone has the dates for each of the hosts, it would be 
> > interesting to compare the growth of IMPs vs growth of hosts.
> >
> > Steve
> > --
> > Internet-history mailing list
> > Internet-history at elists.isoc.org
> > https://elists.isoc.org/mailman/listinfo/internet-history
> >
> >
>
> --
> Geoff.Goodfellow at iconia.com
> living as The Truth is True
> --
> Internet-history mailing list
> Internet-history at elists.isoc.org
> https://elists.isoc.org/mailman/listinfo/internet-history
>
--
Internet-history mailing list
Internet-history at elists.isoc.org
https://elists.isoc.org/mailman/listinfo/internet-history