photocells,feedholephotocell,andlightsourcecontrol
photocell).Thetapeguidesmayberetractedbytheopera-
tortoinsertpapertapeintothereadhead.A tape-width
selectorallowsthetapeguidestobecorrectlysetfor5-,6-,
7-,
and8-trackpapertapes.A readingphotocellisposi-
tionedateachtrackofthepapertape.Thetracksarenum-
beredfrom1 through8,workingfrombottomtotopof
thereadhead.
Ifa holeispunchedina trackofthepaper
tape,
suffi-
cientlightpassesthroughtheholetooperatethetrack
photocell.Ifnoholeispunched,insufficientlightpasses
throughthepapertooperatethephotocell.
Theoutputsofalleightreadingphotocellspasstothe
2822.
FeedHole Photocell
Thefeedholephotocelldetectsthefeedholesinthetape.
Thephotocelloutputisusedtocontrolthefeedingoftape
intothesupplystacker(ifthesupplyfeatureisequipped),
andtostopthereaderdriveifnofeedholesaredetectedin
asectionoftape.
Light
Source
Control Photocell
Thisphotocellisusedtocontroltheintensityofthelight
source.Thephotocellispositionedbetweentrackssothat
variationsinthelightpassingthroughthepaperare
detected(duetochangesinpaperthickness,forexample).
Theoutputofthephotocellisusedtocontrolthelight
sourcesupply,sothatthedifferenceinlightintensity
betweenholeandno-holeconditionsmaybeheldconstant.
ReaderDrive
Thereaderdrivemotoroperatescontinuouslyafterpower-
on.Thereaderdriveclutchiscontrolledfromthe2822,
andwhentheclutchengagestheidlerroller,thepapertape
isdrawnthroughthe2671ata maximumspeedof1,000
characterspersecond.Whentheend-of-tapesensoroper-
ates,
a signalissenttothereaderdriveclutchcontrollogic
todisengagetheclutch,independentlyofthe2822.
ReaderBrake
Thereaderbrakehastwobrakingsurfaces.Thebrakingsur-
facesareforcedtogetherbyanelectromagnet,controlled
bythe2822.Theefficiencyofthebrakingactionissuch
thatthetapestopsonthenextcharactertoberead,regard-
lessofthespeedofthetape.
Note: Thereaderdriveandthereaderbrakearecontrolled
sothatwhenthereaderdriveisengagedthereaderbrakeis
released,andviceversa.
End-of-TapeSensor
Thepapertapepassesoverthefeelerofa microswitch,
whichistheend-of-tapesensor.Assoonasthereisnotape
inthesensor,themicroswitchoperates.Themicroswitch
contactsarewiredtothereaderdriveclutchsothatthe
clutchisdisengagedwhenthemicroswitchoperates.
Specification
ofTapeBasket
Toavoidtapefrombeingspilledontothefloorifthetake-
upfeatureisnotfitted,thecustomerisadvisedtohave
madea basketofthefollowingdimensions:
Height:39in.(99cm)
Length:20in.
(51
cm)
Width: 24in.(61cm)
Thebasketshouldbemadeofwoodorcardboard,but
notofmetal.Metalbasketscauseelectrostaticdischarges
whichcaninterferewiththeoperationofthe2671/2822,
andalsootherunitsnearby.
TapebasketsarenotavailablefromIBM.
SPECIALFEATURESFOR2671
Inordertoreadreelsofpunchedpapertapeandtoreelthe
tapeafterreading,thefollowingspecialfeaturescanbe
supplied:
1.
Supply(reel-feeding)feature.
2.
Center-rollfeature.
3.
Take-upfeature.
Thesupplyfeatureisa prerequisiteforthecenter-roll
feature.
SupplyFeature
Thesupplyfeature(seeFigure2)feedspunchedpaperfrom
areelintothesupplystacker.Thetapeisdrawnoutofthe
stackerbythereaderdrive.Thetapeisreeledofftokeep
thestackerfullatalltimes;thesupplymotoriscontrolled
byphotocellslocatedinthestacker.
Thereelmaybewoundclockwiseorcounterclockwise,
butisalwaysreeledofftheoutsideofthespool.Thetape
reelalwaysneedstoberewoundbeforeitisusedagain.
Themaximumsupplyspeedintothestackeris500
characterspersecond.
Theinsideofthediameterofthereelmaybe4-1/2in.
(12
cm)or2 in.(5cm);thefeaturehasbothtypesofhub.
Theoutsidediameterofthehubmustnotexceed10.5in.
(27cm).
Ifthereelistobewoundontothetake-upfeature,then:
1.
Totaltypelengthmustnotexceed1,000ft(305m).
2.
Tapeleadermustbeatleast20in.
(51
cm)long.
Forstripfeeding,theleadermustbeatleast6 in.
(15
cm)
long.
Foralltypesofuse,thetapetrailermustbeatleast3 in.
(8cm)long.
Center-RollFeature
Thesupplyfeatureisa prerequisiteforthecenter-roll
feature.
Thetapeispulledfromtheinsideofthespoolbymeans
