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␈↓ ↓N␈↓α␈↓ b1


␈↓ ↓N␈↓ε␈↓ α¬Communicating by DIALNET                    ␈↓ π∞␈↓throughout␈α"the␈α!country,␈α"and␈α"in␈α!which
␈↓ ↓N␈↓ε␈↓ α&␈↓αJohn McCarthy and Les Earnest               ␈↓ π∞␈↓comments␈α
from␈α
readers␈αare␈α
accessible␈α
to␈αother
␈↓ ↓N␈↓α␈↓ α>␈↓↓Computer Science Department                 ␈↓ π∞␈↓readers.
␈↓ ↓N␈↓↓␈↓ βStanford University
                                            ␈↓ π∞␈↓The␈α∞usefulness␈α∞of␈α∞the␈α∞Arpanet␈α∞has␈α∞prompted
␈↓ ↓N␈↓Electronic␈αmail␈αand␈αother␈αcommunications␈αcan     ␈↓ π∞␈↓many␈α≡non-defense␈α≡installations␈α≡to␈α≡try␈α≥to
␈↓ ↓N␈↓be␈α↔sent␈α↔between␈α↔computers␈α↔using␈α↔ordinary         ␈↓ π∞␈↓connect␈α∀to␈α∀it.␈α∀In␈α∀some␈α∀cases␈α∀this␈α∃has␈α∀been
␈↓ ↓N␈↓telephone␈αlines.␈α Even␈αthough␈αthis␈αwould␈αbe␈αa      ␈↓ π∞␈↓possible,␈α≡but␈α≡often␈α≡the␈α≡institutional␈α≡and
␈↓ ↓N␈↓very␈α∪valuable␈α∪service␈α∪for␈α∪many␈α∀people␈α∪and         ␈↓ π∞␈↓≡nancial␈α≤obstacles␈α≤have␈α≤been␈α≠insuperable.
␈↓ ↓N␈↓organizations,␈α∩it␈α∪is␈α∩not␈α∩yet␈α∪widely␈α∩available.    ␈↓ π∞␈↓The␈α
main␈α
≡nancial␈α
obstacles␈α
are␈α
the␈α∞need␈α
for
␈↓ ↓N␈↓The␈α∂primary␈α∂barrier␈α∂to␈α∂development␈α∞appears       ␈↓ π∞␈↓a␈α∩dedicated␈α⊃computer␈α∩at␈α⊃each␈α∩site␈α∩called␈α⊃an
␈↓ ↓N␈↓to␈α
be␈α∞the␈α
lack␈α
of␈α∞suitable␈α
standards␈α∞for␈α
inter-     ␈↓ π∞␈↓IMP,␈α
costing␈α
about␈α∞$80,000,␈α
and␈α
the␈α∞need␈α
for
␈↓ ↓N␈↓computer communication.                     ␈↓ π∞␈↓dedicated␈α⊂communication␈α⊂lines␈α⊂rented␈α⊃by␈α⊂the
                                            ␈↓ π∞␈↓Department␈α
of␈α
Defense␈α
at␈α
great␈α
expense␈α
from
␈↓ ↓N␈↓Beginning␈α→in␈α→July␈α→1977,␈α→a␈α~project␈α→called          ␈↓ π∞␈↓the␈α~telephone␈α~companies.␈α~ Other␈α~networks
␈↓ ↓N␈↓␈↓↓Dialnet␈↓␈α∞was␈α
organized␈α∞at␈α∞Stanford␈α
University     ␈↓ π∞␈↓have␈α∪been␈α∪started,␈α∪some␈α∪for␈α∪particular␈α∩user
␈↓ ↓N␈↓to␈α⊂tackle␈α⊂this␈α⊂problem,␈α⊂under␈α⊃sponsorship␈α⊂of      ␈↓ π∞␈↓populations␈α∪and␈α∪others␈α∪as␈α∀common␈α∪carriers.
␈↓ ↓N␈↓the␈α
National␈α
Science␈α
Foundation.␈α
 The␈α
Dialnet    ␈↓ π∞␈↓However,␈α∪they␈α∩have␈α∪higher␈α∩base␈α∪costs␈α∩than
␈↓ ↓N␈↓goal␈α
is␈α
a␈α
set␈αof␈α
protocols␈α
enabling␈α
a␈αcomputer      ␈↓ π∞␈↓can␈α~be␈α~achieved␈α≠with␈α~direct␈α~use␈α≠of␈α~the
␈↓ ↓N␈↓user␈α≠at␈α~a␈α≠terminal␈α~attached␈α≠to␈α≠his␈α~own             ␈↓ π∞␈↓telephone␈αsystem␈αand␈α
they␈αdon't␈αpresently␈α
o≥er
␈↓ ↓N␈↓computer␈α⊂to␈α⊂send␈α⊂messages␈α⊂to␈α⊂users␈α⊃of␈α⊂other        ␈↓ π∞␈↓general␈α message,␈α∨≡le␈α transfer␈α and␈α∨login
␈↓ ↓N␈↓computers,␈α⊃to␈α⊃transmit␈α⊃≡les␈α⊃between␈α⊃his␈α⊂own       ␈↓ π∞␈↓services.
␈↓ ↓N␈↓and␈α⊂other␈α⊂computers,␈α⊂and␈α⊂to␈α⊂use␈α⊂other␈α∂time-
␈↓ ↓N␈↓shared␈α"computers␈α"directly¬all␈α#using␈α"the         ␈↓ π∞␈↓The␈α~Dialnet␈α~protocols␈α~will␈α~make␈α→network
␈↓ ↓N␈↓existing␈α dial-up␈α telephone␈α!network.␈α  His        ␈↓ π∞␈↓services␈αavailable␈αto␈αany␈αtime-shared␈α
computer
␈↓ ↓N␈↓computer␈α
will␈αneed␈α
an␈αautomatic␈α
dialer␈α
and␈αa       ␈↓ π∞␈↓installation␈α⊗or␈α↔single␈α⊗user␈α↔computer␈α⊗system
␈↓ ↓N␈↓suitable␈α~modem␈α≠and␈α~must␈α≠implement␈α~the            ␈↓ π∞␈↓without␈α⊃having␈α⊃to␈α⊃join␈α⊃any␈α∩formal␈α⊃network.
␈↓ ↓N␈↓Dialnet␈α∞protocols␈α∂in␈α∞its␈α∞operating␈α∂system.␈α∞ No    ␈↓ π∞␈↓The␈α
hardware␈αcost␈α
will␈α
be␈αfrom␈α
$500␈αto␈α
$5000,
␈↓ ↓N␈↓formal␈α'network␈α'administration␈α'will␈α'be           ␈↓ π∞␈↓depending␈α∀on␈α∪the␈α∀type␈α∪of␈α∀system␈α∀and␈α∪how
␈↓ ↓N␈↓required.␈α# The␈α"users␈α#of␈α#any␈α"computer             ␈↓ π∞␈↓di≠cult␈α≤it␈α≤is␈α≥to␈α≤connect␈α≤devices␈α≥to␈α≤the
␈↓ ↓N␈↓implementing␈α∃the␈α∃protocols␈α∃will␈α∃be␈α∃able␈α∃to        ␈↓ π∞␈↓computer.␈α" For␈α"time-sharing␈α"systems,␈α"an
␈↓ ↓N␈↓communicate␈α_with␈α↔the␈α_users␈α↔of␈α_any␈α↔other           ␈↓ π∞␈↓automatic␈α≠telephone␈α~dialer␈α≠will␈α≠allow␈α~the
␈↓ ↓N␈↓computer␈α
implementing␈α
them¬anywhere␈α
in␈α
the      ␈↓ π∞␈↓system␈α⊂to␈α⊂initiate␈α⊂calls.␈α⊂ For␈α⊂small␈α⊂single-user
␈↓ ↓N␈↓world.                                      ␈↓ π∞␈↓systems␈αwhere␈αeconomy␈αis␈αparamount,␈αthe␈αuser
                                            ␈↓ π∞␈↓can␈α~do␈α~his␈α→own␈α~dialing.␈α~ There␈α~will␈α→be
␈↓ ↓N␈↓Services␈α
very␈α
similar␈αto␈α
these␈α
are␈α
available␈αin    ␈↓ π∞␈↓programs␈α∞to␈α∞transmit␈α∞signals␈α∞and␈α
information
␈↓ ↓N␈↓the␈α⊗␈↓↓Arpanet␈↓,␈α⊗which␈α⊗was␈α⊗developed␈α⊗by␈α⊗the           ␈↓ π∞␈↓according␈α∪to␈α∩the␈α∪protocols.␈α∪ Any␈α∩installation
␈↓ ↓N␈↓Department␈αof␈αDefense␈αand␈αlinks␈αhundreds␈αof       ␈↓ π∞␈↓implementing␈α∃the␈α∃protocols␈α∃will␈α∃be␈α∃able␈α∃to
␈↓ ↓N␈↓computers␈α⊂around␈α⊂the␈α⊂world.␈α⊂ These␈α⊂services      ␈↓ π∞␈↓communicate␈α≥with␈α≡any␈α≥other.␈α≡ The␈α≥only
␈↓ ↓N␈↓have␈α∞proven␈α∞valuable␈α∞in␈α∞aiding␈α
collaboration     ␈↓ π∞␈↓disadvantage␈α
compared␈αwith␈α
the␈α
Arpanet␈αwill
␈↓ ↓N␈↓among␈α∃computer␈α⊗scientists␈α∃at␈α⊗di≥erent␈α∃sites      ␈↓ π∞␈↓be generally lower speed.
␈↓ ↓N␈↓and␈αin␈αpermitting␈αnationwide␈αaccess␈αto␈αunique
␈↓ ↓N␈↓facilities␈α↔such␈α↔as␈α↔the␈α↔Macsyma␈α↔system␈α↔for         ␈↓ π∞␈↓Like␈αArpanet,␈α
Dialnet␈αwill␈α
be␈αmost␈αuseful␈α
with
␈↓ ↓N␈↓computing␈α&with␈α&algebraic␈α&and␈α&analytic           ␈↓ π∞␈↓␈↓↓full␈α
time-sharing␈αsystems␈↓␈α
that␈α
operate␈α24␈α
hours
␈↓ ↓N␈↓expressions␈α⊗at␈α∃M.I.T.␈α⊗ They␈α∃permit␈α⊗a␈α∃new          ␈↓ π∞␈↓a␈α
day␈α
and␈α
have␈α
≡le␈α
systems.␈α
 In␈α∞such␈α
systems,
␈↓ ↓N␈↓form␈α⊂of␈α⊂publication␈α⊂in␈α⊂which␈α⊂documents␈α⊂are        ␈↓ π∞␈↓each␈αuser␈α
has␈αnamed␈α
disk␈α≡les␈α
that␈αare␈αkept␈α
in
␈↓ ↓N␈↓kept␈α in␈α the␈α computer,␈α!are␈α continuously           ␈↓ π∞␈↓the␈α∂system␈α∂even␈α∂when␈α∞he␈α∂is␈α∂absent,␈α∂and␈α∞new
␈↓ ↓N␈↓updatable,␈α5are␈α5immediately␈α4accessible          ␈↓ π∞␈↓≡les␈α
can␈αbe␈α
created␈αby␈α
≡le␈αtransfer␈α
from␈αother
␈↓ ↓N␈↓α␈↓ `2


␈↓ ↓N␈↓machines␈αand␈α
on␈αreceipt␈α
of␈αmessages.␈α
 E≠cient
␈↓ ↓N␈↓use␈α
of␈α
the␈αmessage␈α
facilities␈α
normally␈αrequires
␈↓ ↓N␈↓that␈α
users␈α
habitually␈α
log␈α
in␈α
each␈α
working␈αday
␈↓ ↓N␈↓and␈α_are␈α_most␈α_bene≡cial␈α_when␈α→users␈α_have
␈↓ ↓N␈↓individual␈α∪display␈α∪terminals␈α∪in␈α∪their␈α∪o≠ces.
␈↓ ↓N␈↓Further␈α≠bene≡ts␈α≠accrue␈α≠when␈α≠reports␈α≠are
␈↓ ↓N␈↓normally␈α_prepared␈α_at␈α_terminals␈α_and␈α↔when
␈↓ ↓N␈↓secretaries␈α∨use␈α terminals␈α∨for␈α letters␈α∨and
␈↓ ↓N␈↓messages.

␈↓ ↓N␈↓While␈αthe␈α≡rst␈α
users␈αof␈αDialnet␈α
are␈αlikely␈αto␈α
be
␈↓ ↓N␈↓regular␈α~computer␈α~users,␈α≠the␈α~corresponding
␈↓ ↓N␈↓Arpanet␈α∪facilities␈α∪have␈α∩been␈α∪much␈α∪used␈α∩by
␈↓ ↓N␈↓non-programmers.␈α∞ Users␈α∂of␈α∞Dialnet␈α∂need␈α∞not
␈↓ ↓N␈↓know␈α
how␈α∞to␈α
program,␈α∞and␈α
increasing␈α∞use␈α
by
␈↓ ↓N␈↓non-programmers␈α~is␈α~expected␈α≠as␈α~terminals
␈↓ ↓N␈↓become more widespread.

␈↓ ↓N␈↓The␈α⊃economics␈α⊃of␈α⊃sending␈α⊃messages␈α∩and␈α⊃≡le
␈↓ ↓N␈↓transfer␈αby␈αDialnet␈αare␈αquite␈αfavorable␈αwithin
␈↓ ↓N␈↓a␈α∪single␈α∪country.␈α∪ Using␈α∪Dialnet␈α∪for␈α∪remote
␈↓ ↓N␈↓login␈α⊂is␈α⊂economical␈α⊂only␈α⊂within␈α⊂a␈α⊃local␈α⊂area,
␈↓ ↓N␈↓because␈α↔longer␈α↔connect␈α↔times␈α↔are␈α⊗generally
␈↓ ↓N␈↓involved.

␈↓ ↓N␈↓Preliminary␈α↔protocols␈α↔may␈α↔be␈α↔available␈α↔as
␈↓ ↓N␈↓early␈αas␈αSpring␈α1978,␈α
and␈αa␈α"≡nal"␈αversion␈α
will
␈↓ ↓N␈↓be␈α∀available␈α∀by␈α∀the␈α∀end␈α∀of␈α∃1978.␈α∀ Anyone
␈↓ ↓N␈↓interested␈α_in␈α↔implementing␈α_the␈α↔preliminary
␈↓ ↓N␈↓protocols␈α∞or␈α∂in␈α∞in∨uencing␈α∂them␈α∞is␈α∂invited␈α∞to
␈↓ ↓N␈↓communicate with the authors.