Model 444 TeleprinterTechnical Specification

Contents

Alphabets 2

Answer Back 10

Attachment - Tape Transmitter 12

Attachment - Reperforating 11

Automatic Transmitter 12

Bell 14

Code recognition 13

Circuits 2

Connections (external) 3

Construction 2

Controls 5

Copy holder 15

CR/LF (combined) 15

CR/LF (automatic) 15

Cover 6

Dimensions 2

Divide 2

Drive 3

Electromagnet 2

End-of-Line warning 14

Finish 14

Governor 7

Governed motors 7

Hours counter 14

Horizontal tabulator 15

Interference suppression 10

Introduction 1

J-bell 14

Keyboards 8

Line current 2

Local record 3

Maintenance 3

Margin 2

Motors - Governed 7

Motor range 3

Motors - synchronous 7

Motor control switch 10

Noise reduction 9

On-speed indication 13

Optionals 2

Orientation 2

Packing 14

Paper 5

Paper-out 15

Parallel input 15

Parallel output 15

Printing mechanism 4

Reperforating Attachment 11

RIS 10

Safety precautions 9

Signal divide 2

Six-unit operation 15

Speeds 2

Stationery 5

Stunt-Box 13

Synchronous motors 7

Tabulator 15

Tape Punch 11

Tape Reader 12

Tape Transmitter 12

Third shift 14

Transmitter (Keyboard) 9

Two-colour printing 14

Weight 2

Who are you? 10

2-colour printing 14

3rd shift . 14

6-unit operation 15

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IntroductionThe new Creed Model 444 (pronouncedFour, forty-four) is a heavy-duty page-printing teleprinter developed primarilyto satisfy British Post Office require-ments for a Telex machine to CCITTstandards. It can operate in either thesimplex or the duplex mode at speedsup to 75 bauds, and is compatible withthe majority of teleprinters and circuitsnow in service. Each character isprinted as soon as it is received by typebars carried in a type basket whichmoves to and fro in front of the station-ary paper carriage.A range of additional optional featureshas been planned to enable themachine to be used in specialised high-speed telecommunications and dataprocessing applications.

The machine has been designed tooperate continuously for long periodsand to function reliably with the mini-mum of maintenance attention. Withsuitable lubricants and ribbon, it willremain serviceable at temperatureswithin the range -25°C to -55°C.Although the Model 444 is basically a5-unit, start-stop, two shift machineoperating on International TelegraphAlphabet No 2, provision has beenmade in the receiving mechanism for athird shift to which access is made viaone of the optional secondaries (F, G orH) or by the 'all space' code SSSSS.Provision has also been made forsubsequent adaptation to 6-unitoperation (with shift) throughout theReceiver, Keyboard, Transmitter, TapePunch Unit, and Tape Reader Unit.

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ConstructionRobust 'unit construction' for easymaintenance and accessibility. Eachmajor unit is carried on its own castingor frame, and is secured by no morethan four screws. Where appropriate, egon the motor unit, the screws have beenmade captive. Abutments are providedto locate the units accurately.All units are interchangeable withoutneed to re-adjust except in isolatedcases. Individual components havebeen designed for easy assembly withthe minimum number of adjustments.Units can be dismantled and thenreassembled without need for readjust-ment.The number of different fabricated partsis approximately 1,250 for a basictransmitter/ receiver version of themachine fitted with a synchronousmotor. A further 160 parts are involvedin the Tape Reader unit, and 220 partsin the Tape Punch unit.

SpeedsMachine is designed for 50 baud and 75baud operation, ie 66 and 100 wordsper minute respectively. Conversionfrom 50 baud to 75 baud operation bychanging motor and hours countergearing. This conversion can be carriedout without removing the motor ordisturbing adjacent units.

Signal DivideThe transmitters associated with thekeyboard and with the tape reader unitare both designed for 7 1/2 unit opera-tion. The teleprinter receiver is designedto accept 7 or 7; unit signals at 50bauds, and at 75 bauds. 8 1/2 unitsignals are used for 6-unit applications.

AlphabetsPrinting in all common Indo-Europeanlanguages is possible up to a maximumof 56 graphics on two-shift version.Semitic languages such as Hebrew andcursive scripts such as Arabic, bothinvolving a right-to-left type baskettraverse action, can be catered for. Useof a third shift increases possiblegraphics to 84. Nonfeeding type barscarrying 'accents only' are possible.

OptionalsThe basic Model 444 machine consistsof a 5-unit, 50 baud or 75 baudreceiving mechanism fitted with a 3-rowor 4-row keyboard, the answer-backfacility, an end-of-line warning lamp, thetwo-colour printing facility, and a motorhours counter.Optional units and facilities that can befitted to the basic machine include aTape Punch unit, a Tape Reader unit,an automatic motor switch, a motor on-speed relay, paper-out contacts, a coderecognition unit (stunt box), an auto-matic carriage-return line-feed facility, a5- or 6-unit parallel input unit, and aparallel 5or 6-wire output from the coderecognition unit.Special facilities envisaged for Model444 will include horizontal (repeatspace) tabulation, and provision for aparallel 5or 6-wire output direct from thekeyboard transmitter (as distinct fromthe multi-wire output from the coderecognition unit). The machine can besupplied as a transmitter-receiver, or asa receiver only. Answer-back andparallel input unit can be fitted tomachines without keyboards.

Dimensions and WeightExternal overall dimensions of themachine in its sound-reducing cover arewidth 20½ inches 52.0 cmdepth 25 5/8 inches 65.1 cmheight 12¾ inches 32.4 cmWeight of a keyboard machine with aTape Reader and a Tape Punch and thesoundreducing cover is approximately82 pounds (37.2 kg). This figure doesnot include the weight of the paper rolland the tape reel. The sound-reducingcover and its base tray weigh approxi-mately 25 pounds(11.3 kg).

Receiving Electromagnetand OrientationThe standard polarised receivingelectromagnet is designed to respondto doublecurrent signals, but can beconverted for single-current use byattaching biassprings to its armature. Manualorientation adjustment determinesselection instant over -60% of a codeelement length. Scale is calibrated toread receive margin directly.

Line Current and MarginLine current for the polarised electro-magnet working on double currentsignals is 20 mA (80-80V). Singlecurrent working (using bias springs) willrequire 40 mA (120V). The receivemargin is at least -42% at 50 bauds,and --38% at 75 bauds.

CircuitsFull Duplex, Half Duplex, or Simplex(single or double current) with electricallocal record facilities. Local circuitry forModel 444 is similar to that used forCreed Model 7 and Creed Model 54;the new machine is therefore inter-changeable with these earlier ma-chines. It will not be interchangeablewith Creed Model Seventyfive circuitrybecause of the mechanical local recordfeature of that machine, althoughModel 444 can work to a ModelSeventy-five or to any other make ofteleprinter which conforms to CCITTstandards.

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Local RecordElectrical local record on double-currentcircuits is obtained by leaking signalsfrom send line back to local electro-magnet. The leak resistor is by-passedand incoming signals connected directlyto electromagnet by an automaticsendreceive switch. Single-currentcircuits obtain local copy by inclusion ofreceive electromagnet coils in loopcircuit. In both these modes an accu-rate local copy is proof of accuratetransmission.

DriveTransmitting and receiving mechanismsare driven by a single 3000 rpm or3750 rpm electric motor. Receiveremploys three cam shafts (selector,main receive cam shaft, and typebasketfeed shaft) each making half a revolu-tion for each character. The keyboardtransmitter has a single cam shaftwhich, for maximum accuracy, makesone complete revolution for eachtransmitted character.Both the ratchet and the friction type ofclutch is used on the machine. Theratchet clutches incorporate africtiondriven element which providesthe homing torque, helps to equalisethe idling/ running load, and reducesimpact when the drive is engaged.

Motor RangeSeries wound, 3750 rpm, ac single-phase governed motors for any singlevoltage in range 100-125V (5-voltsteps), 200-250V (10-volt steps), at 40,50 and 60 cps. Series wound 3000 rpmd.c. governed motors initially for BritishPost Office, 3750 rpm do motorsavailable in future, if required. Rangeenvisaged is 100-125V (5-volt steps),160V, 200-240V (10-volt steps).Synchronous motors for 50 cps (3000rpm) and 60 cps (3600 rpm) supplies,and any single voltage in range 110-125V (5-volt steps), 200-250V (10-voltsteps).

Power and SignallingConnectionsSeparate captive cables are providedfor motor power (3-way), and forsignalling circuits (40-way). Provisionfor an additional 40-way plug andcaptive signals cable for code recogni-tion contacts, if capacity of standardcable is exceeded. Electrical connec-tions from the base tray, in which thepower and signalling cables terminate,to the teleprinter mechanism are madevia a 40-way Plessey series 110 jack-inconnector for the signals wiring, and a6-way Painton Multicon connector (withtwin earth pins) for the motor powersupplies. Power supply from theteleprinter main base to the motor unitis via another 6-way Painton Multiconconnector. The signals and motorconnectors are located at the rear ofthe machine main base adjacent to themotor gearing. Space has been leftaround all unit connectors so thatalternative types of plug with a largernumber of pins can be fitted whenrequired.

MaintenanceRoutine maintenance for 50-baudmachines will consist of inspection,cleaning, and lubrication after each1000 hours of operation, or at intervalsof one year, whichever is earlier. Theoverhaul interval is 5000 hours or 5years, whichever is earlier. Mainte-nance intervals for 75baud working areto be 500 hours initially, with overhaulat 3000 hours or 3 years.All lubrication points requiring attentionat the routine maintenance interval canbe reached without dismantling. Onlytwo lubricants: a light oil and a greasewill be required. It will not be necessaryto relubricate shielded motor bearingsas the original lubricant inserted by thebearing manufacturer will last until thebearings are replaced at 5000 hours.All field maintenance can be carried outwith common tools. Gauges will beavailable to simplify certain adjust-ments. Main cover and lid are securedto the base tray by two Oddie clipswhich require a quarter-turn with ascrewdriver to release them and soenable the cover to be lifted off. Therelease of two sliding latches, and thedisconnection of the internal power andsignals plugs at the rear of the mainbase, enables the complete receivingand transmitting mechanisms to belifted out of the base tray, while theinput sockets and their cabling remainclamped inside the tray.

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Printing MechanismThe printing mechanism of Model 444employs a moving typewriter-style typebasket, and a stationary platen unitwhich bears the paper roll. The typebasket can hold up to 28 type barseach carrying two characters, so givinga maximum capacity of 56 characters.Provision has been made for increasingthis capacity by the use of a third shiftposition.A type bar is selected by allowing it todrop into a slot across an arrangementof five castellated comb bars carried onthe type-basket carriage unit andcontrolled by five vanes which arepivoted on the frame of the machine.These vanes are in their turn controlledby the selection mechanism and theincoming signals which it registers. Thedownward movement of the selectedtype bar brings it into the path of a printbail which lifts the bar out of its basketand so impresses the type against theribbon to create an image on the paper.Each character is printed as soon as itis received and the whole printing lineis visible while it is being printed.The case shift action is obtained byraising the rod on which the type barspivot so as to bring the letters to theprinting line, and by lowering the pivotagain to bringfigures, symbols, and punctuationmarks to the printing line.

The typebasket unit runs on threeparallel rails (two guide rails and theshift rail), and is returned to thebeginning of the line by a helical springwhich is progressively extended as thebasket moves along the printing line.On receipt of a 'carriage return' signalthe feed mechanism is disengaged andthe basket is drawn rapidly back to theleft-hand margin position where theimpact is absorbed by an air dashpot.The 'carriage return' time (about 200 msat normal temperatures) is shortenough to permit a 'carriage return, linefeed, print' sequence at speeds up to75 bauds. It is not therefore necessaryon this machine for a dummy 'lettershift' combination to be inserted after a'carriage return, line feed' sequence toallow the carriage time to return from along line.Printing is through a half-inch widetypewriter ink ribbon which is wound ona flanged spool of the type used onCreed Model 47 and Model Seventy-five machines. The European standardtypewriter spool DIN 2103 can also beused. The automatic ribbon feedchangeover mechanism will be oper-ated by either a plain or an eyelettedribbon. A mechanically-operatedautomatic two-colour printing facility isstandard; transmitted copy normallybeing printed in red, and receive copyin black.

The printing action and the letter feedaction can be made inoperative, eitherindividually or jointly, on up to maximumof ten combinations. These normallyinclude Carriage Return, Line Feed,Bell, WRU, Letters, Figures and AllSpace. The remaining three combina-tions are available for accents ordiacritical signs. An eleventh combina-tion, with print suppression only, isnormally allocated to Letter Space.Letter spacing, ie the distance betweencentre lines of adjacent characters onthe same line, is io inch nominal.Line length is adjustable from 69 to 75characters. The letter feed and dashpotmechanisms can be reversed to providethe right-to-left traverse required fornon-roman alphabets.

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StationeryBritish, European, and American paperrolls, both in their normal andreversewound forms, can be accommo-dated inside the sound-reducing cover.Maximum width for paper rolls is 82inches (216 mm). Maximum diameter ofroll5 inches (127 mm). Paper guide can beset by operator to accept either 8.3 inch(210 mm) or 82 inch (216 mm) widepaper. Provision for external papersupply, and for sprocket-feed printedstationery. Provision for small sprocket-feed packs within cover; a drop-incontainer can be substituted for papertube.Machine can be fitted with a friction-feed platen, or with a dual-purposefriction/ sprocket feed platen withretractable pins which is capable ofbeing set to accept either plain paper ormarginally-punched printed stationery.Platen units can be interchangedwithout dismantling other units frommachine. Platen material is Langitex ason previous Creed teleprinters. Anexternal knob is provided to turn theplaten and so advance the paper.Platens will accept friction-feed paper,either single-ply or up to 6-ply, with orwithout interleaved carbon sheets, andalso carbonless multi-plies such asNCR paper. Print force is adjustable bymechanic and can be set to print up tosix carbon copies.

Line length adjustable from 69 to 75characters. Left-hand margin is 0.55inch (13.9 mm) minimum from edge ofpaper to centre line of first character,and can be adjusted inwards over 4character spaces. Right-hand margin isalso 0.55 inch(13.9 mm) minimum for a 75-characterline on 82 inch (216 mm) wide paper.This setting can also be adjustedinwards over 4 character spaces. (69-character line will normally be set to0.75 inch (19 mm) lefthand margin on8.3 inch (210 mm) paper). Threedegrees of line feed by operator setting:1/6 inch, ,'- inch, and 1/3 inch, ie4.23 mm, 6.35 mm, and 8.46 mmrespectively.

Note 1 Run-out occurs on last key depressed, ie to start continuous transmission,depress the selected key, release it, and then depress the run out key.

Note 2 This override key prevents operation of mechanical and/or electromagnetic'Perf Off' facility. It is an optional facility.

Note 3 Operating this key releases the tape so that it can be pulled through thepunch mechanism.

Note 4 These keys operate their respective functions without sending signals toline. Manual carriage return is standard; key will return carriage even if motor isswitched off. Manual line feed and shift control keys will only operate the receiver ifit is already cycling, ie they cannot initiate a cycle. These keys are intended only foremergency use to correct corruptions, or to remedy the omission of a shift, CR, orLF signal by the distant operator.

Operator's Manual Controls

Keyboard: Maximum of 59 key buttons, plus two shift pads and aspace bar.

Platen Controls: Platen pressure roller ON/OFF control lever Line feedcontrol leverPaper guide-face setting Platen knob

Functional keys: HERE IS keyRUN OUT key (see Note 1)CARRIAGE RETURN key

Optionals: LINE FEED keyLETTER SHIFT key (see Note 4)FIGURE SHIFT key

Tape Punch Unit: PERF OFF key PERF ON key BACK SPACE key ONOVERRIDE key (see Note 2)TAPE RELEASE key (see Note 3)Catch to release panel covering cuttings box

Tape ReaderUnit:

TRANSMITTER ON keyTRANSMITTER OFF keyTape gate release push buttonSingle-shot button (optional)

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CoverA three-piece metal cover consisting ofa base tray, a cover unit proper, and acounterbalanced lid totally enclose theteleprinter mechanism and so reducemachine noise to a minimum. The TapeReader unit, the Tape Punch unit, an 8-inch diameter tape reel, and a paperroll up to 5-inch diameter (or alterna-tively a small sprocket-feed pack) canall be accommodated within this cover.The fitting of the Tape Reader and TapePunch units only affects the keyboardmask, which is readily interchangeable.Receiver-only applications are satisfiedby filling the keyboard aperture of thestandard cover with a dummy panel.All three cover units, which togetherweigh about 25 pounds, are aluminiumpressure die castings some 1/10 inchthick, and are lined with sound-reducingplastic foam to give good noise insula-tion. The joints between the tray andcover, and between the cover and lidare sealed with a rubber strip.The lid is lightly spring-loaded towardsthe closed position, and is also stable inthe fully-opened position to give easyaccess to the tape reel, paper roll andribbon.The operator views the printing positionthrough a 12-inch wide transparentplastic visor which has been designedso that reflections from room lighting donot reach the operator's eyes. A paperknife is incorporated in the top face ofthis visor. Recessed hand-holds areprovided at the left-hand and right-handsides of the base tray. By lifting thefront of the machine slightly, its weightis transferred from its four rubber feet totwo rollers located at the rear of thebase tray so enabling the machine tobe wheeled to a new position. The entrypoints of the power and signal cords,which are located at the rear of thebase tray, are recessed so that thecables will not be trapped when themachine is moved in this fashion.Cables can be completely concealed ifa suitable hole is provided in the desktop. Provision has been made to extendthe Tape Punch unit cuttings chutethrough the base tray into a largecontainer inthe desk.

The cover and external controls weredesigned by David Mellor R.D.I.,Des.R.C.A.

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Governed MotorsA full range of 3750 rpm ac, and 3000rpm dc, governed motor units has beendesigned. As these units contain all theassociated electrical equipment suchas governing resistor, on-speed relay,and radio interference suppressioncomponents, and plug directly into themain base wiring, it is a simple opera-tion to exchange a motor unit, ortosubstitute one of a different type orvoltage.The motor unit also contains themicroswitch associated with theautomatic motor switch facility. Thisswitch is operated by a lever from amechanical time delay mechanismlocated on the teleprinter main base.The motor and its governor areprotected by a metal cover which isforce ventilated through louvres at therear of the base tray. This covercompletely encloses the motor andgovernor, and is retained by a singlescrew; live surfaces such as brushboxes, which would otherwise beexposed when the main cover isremoved, are protected by individualplastic covers. In addition to reducingradio interference and noise, andpreventing accidental contact withrotating parts, this overall coverprevents brush dust from finding its wayon to the teleprinter mechanism andalso prevents the motor ventilationsystem from drying out the lubricants.Governed motors will reach correctoperating speed within 1½ seconds atnormal temperatures and nominalsupply voltage. A centrifugal governor(see section headed 'Governor')compensates for temperature variationsand for supply voltage variations of±10% holding motor to within ±0.1% ofthe correct speed. Speed remainsstable within ±0.5% over 1000 hours ofcontinuous running.

Brush life averages 2000 hours whenthe machine is operating at 50 bauds.Brushes are similar to those used onCreed Model Seventy-five but arelonger (¾ inch (19.1 mm) effective) andhave a greater working area. Eachbrush is linked to the power supply byan insulated pigtail, and is held againstthe 45-segment commutator by a spiralspring designed to maintain almostuniform pressure as the brush shortens.Brushes are held in brass boxes carriedon an adjustable plastic moulding andare sited so that the brushes trail. Theeffect of commutator rotation, brushspring pressure, and the offset position-ing of the brush boxes combine topress the brushes against the side oftheir boxes so reducing vibration andsparking.Bearing life of 10,000 hours fixes themotor overhaul interval during whichoperation the commutator will needresurfacing. The two double-shieldedball bearings (British Standard type BRL012) used in the motor are lubricatedby the manufacturer and do not requireany further attention until the 10,000hour interval at which they are replaced.A manually-reset current overloadprotection device is provided asstandard equipment.Resilient rubber mountings locatedbetween the main motor framework andits cradle help to reduce motor noiseand vibration.A black and white 8-segment strobedisc viewed through a 125 dvs (250 cpsshutter speed) tuning fork is providedas a visual speed check.Motor insulation standards are to BritishStandard 2757 Class E.

Synchronous MotorCapacitor-start, capacitor-run motorunits constructed and ventilated asgoverned motors described above, ieunit contains associated electricalequipment, microswitch, overloadprotection, etc. Absence of brushesenables motor overhaul interval to beextended to 10,000 hours at which timethe bearings are replaced. Insulation,resilient mounting, bearings, and otherapplicable data as for governed motors.The motor reaches synchronous speedwithin 12 seconds. The space previ-ously taken up by centrifugal governoris now occupied by a fan.

GovernorA centrifugally-operated governorsimilar in design to those used onprevious Creed teleprinters is em-ployed. This device holds the motorspeed constant to within -0.1% ofnominal in the face of supply voltagevariations of -10%.The governor spring is anchored on abi-metallic bar which flexes to compen-sate for the increase in length of thespring as the motor temperature rises.The manually set speed-adjustmentscrew on the governor spring anchor iselectrically insulated from the mainsupply whatever the position of thegovernor contacts. Governor contactsare tungsten and are 'in (6.35 mm) indiameter.Fins on the outside of the plasticgovernor cover act as a fan to force airover the motor windings and commuta-tor.

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KeyboardsCode selection by action of plain (ieuncontoured) keybars on an arrange-ment of castellated comb bars whoseassociated parallelogram linkages slideto the left or right depending uponcoding.3- or 4-row full or partial shift lockkeyboard arrangements possible. Basicdesign is for a 63-slot board with 59key positions plus two shift keys and aspace bar. The slots for the shift keysand the space bar cannot normally beused for additional keys because of cut-out in standard mask.The standard 4-row layout will have 57operating keys and three pads (ielozenged-shaped keys) for space, lettershift and figure shift. This layoutincludes two spare positions which arenormally filled by non-operating keybars bearing square flat-topped keybuttons which fill up the keyboard maskopening. The maximum number ofoperating keys for a 4-row layout istherefore 59 keys plus 3 pads. Therewill also be a condensed 4row layoutwith 44 keys and one pad. The 3-rowlayout will have 34 keys plus 1 pad, andwill be derived from the condensed 4-row layout by filling the top bank of thekeyboard with square flat-topped

dummy key buttons.Pitch of keys is 3/4 inch (19.1 mm)horizontally and vertically. Slope is 15degrees. Average key pressure is lessthan 6 ounces. Key stroke is 3/16 inchon the top row of keys, and 5/16 inchon the space bar, The individualcylindrical key buttons are inch indiameter.Two basic versions of the keyboardmask are available: the first a plainmask with no apertures for tape units,the second with two apertures, one forthe Tape Reader, the other for the TapePunch. Dummy panels are used to fillthe remaining aperture if only one ofthese optional units is required. Each ofthese masks will have three variations:one with no aperture at all for thekeyboard (suitable for a Receiveronlymachine, or for adaptation to specialkey arrangements), one with a largeaperture to accommodate a 4-row fullshiftlock keyboard, and one with aslightly smaller aperture suitable for acondensed 4-row partial shift-lockboard.The standard keybuttons will normallybe matt black injection-moulded plasticand will have their white characters pre-formed and cast into them at themoulding stage. This method ofmanufacture ensures that the legibilityof the key tops will not be affected even

by prolonged use.Alternative colours, in both keybuttonsand their characters, can be provided.The upper case character on a key canbe in one colour, the lower casecharacter in another colour, and thekeybutton itself in yet another colour.For example, one of these non-standardkeybuttons might be in green, with awhite upper case 'figure' and a blacklower case 'letter'.Special 'organ-type' keys to control theTape Reader and the Tape Punch, andalso to give direct manual control ofsome machine functions, protrudethrough horizontal slots in the front faceof the keyboard mask immediatelyabove the keyboard. These keys aregrouped according to their use and allare within

Typical three- and four-row keyboards.

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easy reach of the operating position.For the British Post Office machinesthese keys will carry plain-languagelegends such as PERF ON, and RUNOUT. As an alternative, a range of keyshave been designed which carry theinternationallyused symbols whichindicate the purpose of each keydiagrammatically, and so avoid theneed for alternative keys to cater forforeign language machines.A storage keyboard for Model 444 isnot envisaged at present.

TransmitterThe Model 444 has a singlechangeover contact, cam-controlled,striker transmitting mechanism which iscapable of generating accurate double-current signals or, by a simple readjust-ment, biasfree single-current signals. Anautomatic send-receive switch isprovided for operation of half-duplex or2-wire circuits. The transmitting mecha-nism is designed for long-term stability,and to be easily adjustable without useof special tools or test equipment.Maximum start-stop synchronoustransmitter distortion figures whenkeying each character separately are:±3% for 50-baud operation ±5% for 75-baud operation A special device is fittedto ensure that Send/Receive switch willreturn to receive at the end of a cycle,however slowly the cycle may havetaken place. This device also provides ashort delay on return to avoid splits inthe stop signal at cadence or near-cadence speed keying.(The Tape Reader unit has its owntransmitter whose contacts, for BritishPost Office applications, will be inseries with those of the KeyboardTransmitter. In these applications theTape Reader will also control the send/receive switch associated with theKeyboard Transmitter).

Noise ReductionSound and vibration reducing measuresinclude the overall metal cover andbase tray with its absorbent lining, therubber mountings and overall metalcover for the motor, and the resilientrubber mountings between the tele-printer main base and the tray.

Electrical SafetyPrecautionsThe machine satisfies the requirementsof the British Post Office SpecificationD1921 A (Protection Requirements forTelecommunication Equipment), therelevant requirements of the European'Commission Equipment Electrique'(CEE) for Electric Motor OperatedAppliances, and British Standard BS613 in respect of leakage current fromthe radio interference suppressioncircuitry to frame.

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Range At mains On send and Noise fieldterminals receive lines at 10m

200 Kc/s-1 Mc/s 500 uV max 10 mV max 50 uV/m max

1 Mc/s-3 Mc/s 100 uV max 3 mV max 30 uV max

3 Mc/s-100 Mc/s 100 uV max 100 uV max 20 uV/m max

100 Mc/s-220 Mc/s 315 uV max 200 [kV max 40 uV/m max

Radio Interference and Spark Suppression

*measurements taken on equipment complying with British Standard 727

Circuitry providing a degree of suppression sufficient to satisfy the requirements ofthe British Post Office, and also those of the European postal administrations, isemployed on Model 444. All transmission contacts are provided with spark quenchcircuitry. Separate interference suppression provision for the Keyboard Transmitter,the Tape Reader, the motor governor contacts and brushes, and for the brushes ofcommutator motors. Maximum levels* of radio interference tolerated by British PostOffice are indicated in the table below. The radiointerference suppression arrangements for Model 444 will satisfy these require-ments.

Motor Control SwitchA mechanically-operated unit whichswitches off the motor automatically ashort time after the end of the mes-sage. At 50 bauds this interval is about72 seconds, and at 75 bauds is 48seconds. The teleprinter motor isstarted again when a space element isreceived from line, or when the 'letters'key on the local keyboard is operated.The microswitch which breaks themotor power circuit is located within themotor unit, and is operated by a levercontrolled from a mechanical time delaymechanism located beneath and drivenfrom the main cam sleeve.The motor switch mechanism can bedisabled by mechanic when notrequired, or the switch can be short-circuited without causing damage.

Answer BackA simple Answer Back device is builtinto keyboard transmitter unit. Aninterchangeable 20-character plasticward drum with break-out projections isused for coding purposes so eliminatingneed to supply a range of pre-cut metalwards.Full freedom of coding on all 20positions of this ward drum, ie it will notbe necessary to have the fixed charac-ter (normally all-mark or all-space) at

the beginning and/or the end of ananswer back cycle to prevent mechani-cal interference with the transmitter, asis required with some other teleprinters.The Answer Back device has a cadencespeed drive, and so transmits to line atthe same speed as the associatedkeyboard transmitter. This featureenables a motor speed check to bemade on a distant and unattendedmachine. The Answer Back mechanismoperates only once for each WRUsignal received, although it will cyclecontinuously while the 'Here Is' is helddown.Answer-back 'off-normal' contacts areprovided. At 50 baud working thesecontacts operate within the ninemillisecond interval between start ofrotation and first start transit. Contactsrestore immediately following end offifth element of the last character. OnBritish Post Office machines a WRUcontact will be connected in tandemwith the 'Off Normal' contact to providean earlier warning of impending answer-back operation.All keys on keyboard are locked duringanswer-back transmission, with theexception of the letter shift key whichmay be depressed but is ineffective. OnBritish Post Office machines, the'letters' key will also be locked. The'Run Out' key, mounted above the mainkeyboard, is not locked while theanswer-back unit is operating, butoperation of this key will not affectanswer-back transmission.The delay between the start transit ofan incoming WRU signal, and the starttransit of the first answer-back code isapproximately 240 milliseconds at 50bauds.The Answer-Back mechanism and theassociated Keyboard Transmittermechanism can be fitted to aReceiveronly version of the machine, ifrequired.

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Tape Punch UnitThis unit, and its associated drivemechanism, is mounted on the left-hand side of the machine within thecover, and so does not increase theoverall width of the machine. It pro-duces 5-track, ',; 6 inch wide tape at themaximum speed of the associatedmachine. The tape, which is fully-punched, feeds out from the punchtowards the operator from beneath aVshaped tear-off face. The unit isoperated from the receiving mecha-nism. It therefore records receivedmessages directly, and transmittedmessages indirectly via the electricallocal record path.

Provision has been made for automaticsuppression of punching on up to fourselected codes which can be in eitheror in both shifts. Two of these codescan be employed for mechanical controlof the 'Perf On' and 'Perf Off' keys.There is also provision for the remotecontrol of the 'Perf On' and 'Perf Off'keys via two electromagnets, one foreach key. If necessary, the unit canpunch all 32 combinations.Centre feed hole tape punching isstandard.A single make contact set (operatingpoint adjustable) which is wired out tothe signals plug provides an alarm for a'tape reel low' condition. Provision canalso be made for sensing the tape

some six inches before the punchingpoint. Absence of tape at this sensingpoint operates another contact set.The Tape Punch and its associateddrive mechanism can be fitted by thecustomer in the field as the necessarydrive cams will be included in the maincam shaft assembly when the machineis built. The controls of the Tape Punchunit are listed in the section headed'Operator's Controls'.

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Tape ReaderThis unit, which is mounted at therighthand side of the keyboard, will read5-track, 11/16 inch fully-punched andchadless tape at the maximum speed ofthe associated teleprinter. It is providedwith its own cam-driven striker transmit-ter complete with radio interferencesuppression circuitry. The tape feedsfrom right to left and a deflector isprovided to guide the tape away fromthe keyboard and towards the operatorafter it has been read. When the unit isON, the teleprinter keyboard is me-chanically inhibited, ie the keybars arefree but ineffective.

The Reader's transmitter has no Send/Receive Switch of its own but sharesthe keyboard's transmitter send/receiveswitch which it controls by means of apush rod. By disabling this controllinkage and also the keyboard inhibitiondevice, and by suitably modifying theexternal electrical control unit, the TapeReader unit can signal to line while theteleprinter receiver, the Tape Punch,and the keyboard are being used off-line to prepare tape. Under thesecircumstances the incoming line willgenerally be terminated by an alarmrelay and a circuit arranged to giveprecedence to the incoming call byoperating the electromagnet whicharrests the Tape Reader. For singlecurrent circuits this electromagnet is inseries with the line, and reacts to thecall or 'spacing start' signal from thedistant station. For double-currentcircuits, this break-in electromagnet isoperated from the control box by arelay. Off-line operation is not possiblewith the British Post Office version ofModel 444 as they require keyboardinhibition on all machines. Electricalindication of the 'Transmitter On'condition is provided by a single

changeover contact set operated by the'On' key. Another changeover contactset indicates when the electromagneticbreak-in mechanism is used or when'tape out' is sensed. Both sets ofcontacts are wired out to the signalsplug and restore when the 'TransmitterOff' key is operated.No 'tight tape' mechanism is provided. A'tape out' sensing mechanism isprovided which senses the tape onceeach cycle at a point just behind thereading line, ie the unit will read the lastcode in the tape and then come to rest.The controls of the Tape Reader unitare listed in the section headed'Operator's Controls'.The unit can be fitted by the customerin the field, as the necessary wiring anddrive will be included when the standardmachine is built.

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Code Recognition Unit(stunt box)The code recognition unit or 'stunt box'provides means whereby 44 codecombinations, in either or in both shifts,can be recognised mechanically andcaused to operate an individual contactset. These contact sets can then beused to control switching operations, toswitch tape units on or off, to changeprinting colour, etc. Except for 'Bell' and'WRU', which are changeovers atBritish Post Office request, the remain-der of these contact sets are normallyfleeting single-make, and all operate forsome 55 milliseconds in each cycle at50 bauds. The 'make' time will bereduced at higher operating speedsand will be of the order of 37 ms at 75bauds. No latching contacts have beenprovided.Contacts of the stunt box can also beused to convert incoming 5-unit (or 6-unit) signals into a parallel 5-wire (or 6-wire) output with shift indication.An additional 40-way signals cord canbe provided for the outgoing wiringassociated with the code recognitioncontacts. Two versions of the stunt boxare envisaged; a 'full' version, and a'basic' version.

The full stunt box code bar coding willprovide:• a make contact to operate on each

of the 32 codes with contactsoperating in both shifts

• a make contact to operate in the'figures' case for codes 6, 7 and 8(F, G and H secondary)

• a changeover contact to operate inthe 'figures' case for codes 4 and 10(WRU and Bell)

• five make contacts to give a parallelcode output

• one make contact to indicate the'figure shift' condition

• one contact to operate as a clockpulse making once every receivecycle and having the same timing asthe other contacts.

Note that the contacts themselves willonly be fitted as required. Arrangementscan be varied widely to suit customer'sspecial requirements.The basic stunt box code bar codingwill only provide contacts for the F, Gand H secondaries, and for codes 27 to32 inclusive (ie the usual functionalcodes). This basic version is to theBritish Post Office Telex requirements,and in this case only the bell and WRUcontact sets will be fitted.

Motor On-SpeedIndicationFor governed motors a relay can beprovided within the motor unit toindicate when the motor shaft hasreached governed speed. On synchro-nous motors a centrifugally-operatedswitch is used to indicate when themotor has reached 75% of synchronousspeed.Output form for both the governed andthe synchronous motors on-speedindication is a single changeovercontact set which is wired out to thesignals plug.

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FinishPlating and other finishes have beendesigned to provide protection ad-equate for indoor use and for storage intemperate climates. This protection issimilar in degree to that provided oncurrent Creed equipment.Subject to certain limitations the finishon Model 444 will also be adequate forgeneral use in tropical climates,although it will not meet all the require-ments of some armed forcestropicalisation specifications. Fortropical service the standard finisheswill have to be supplemented bytreating all unplated parts with acorrosion-inhibiting oil after anydegreasing solvents have been used,and by the use of dessicants and anairtight container when the machine isput into store.Visible steel parts of the platen andoperator's controls will be stainlesssteel or matt chrome plate. Parts of themechanism which are normally freefrom oil are passivated zinc plate, whilesteel working parts have a black oxidefinish followed by treatment withcorrosion-inhibiting oil. Certain steelparts which require a wearresistantsurface are hard chrome plated. Finishto machine cover is a stoved epoxyenamel which is not affected by Creedlubricants or by ordinary solvents suchas white spirit or trichloroethylene usedat room temperatures. This finish willgive a degree of protection in tropicalenvironments superior to that obtainedfrom the hammer-effect enamel atpresent used on Model Seventy-five.The standard colour for the cover willbe the British Post Office Light FrenchGrey, with dark grey for the base tray.The keyboard keybuttons will be mattblack with white legends, and theorgan-type function control keysmounted above the keyboard are blackwith a white legend.

PackingThe machine will be shipped inside itssilencing cover and tray, secured bynuts screwed to extensions of the twospigots whose primary purpose is tolocate the main base casting in thecover tray. When the securing nuts onthese spigots are tightened up, themain base is pulled down against itsresilient mountings until the four plasticfeet on the underside of the basecasting make contact with the base tray.This procedure retains the teleprintersecurely inside the cover. A third fixingpoint is provided by a bolt which screwsthrough the base tray into the motorunit base. The silencing cover and lid isthen placed over the machine, securedby its two Oddie clips, and the lid isclosed.

Hours CounterAn hours counter unit is mounted at thefront of the receiver main base and isvisible to the operator through a smallplastic-filled window located above thekeyboard at a point adjacent to thefunction control keys. It records thelength of time the motor is running, upto 9999 hours, and then resets to zero.The driving gears to the counter mustbe changed for different machinespeeds.

End-of-Line WarningThe standard equipment for end-of-linewarning is an amber lamp mountedabove the keyboard in line with thefunction control keys and the window ofthe motor hours counter. This lamp willlight when the typebasket is nearing theend of the printing line, and its mecha-nism can be set by the mechanic tosignal at the 54th, 55th, or 56thcharacter of a 69-character line.A mechanically-operated single-strokebell can also be provided within thesoundreducing cover to signal when thetypebasket is nearing the end of a line.The bell operating point is adjustable bythe mechanic over the range givenbelow.

line length earliest bell lat-est bell75 characters 55 6669 characters 53 64

The bell can also be arranged to ringwhenever the secondary code of J(MMSMS) is registered by the receiver.

Two-Colour PrintingAn automatic change of printing colouris used to discriminate betweenmessages sent by local keyboardortape reader, and messages receivedfrom line. Provision has been made forremote control of printing colour bymeans of an electromagnet. Two-colourprinting is a standard facility.

J BellSecondary interpretation of J code(MMSMS) operates single changeovercontact in the code recognition unit(stunt box) for some 55 ms (at 50bauds) and then restores. Simultaneousmechanical operation of End-of-Linewarning bell, if required.

Third ShiftProvision has been made for the use ofthree shifts on a 5- or 6-unit input. Forthis mode of operation three charactersare fitted to each type bar in the basketinstead of the usual two, so increasingthe number of possible graphics to 84(3 x 28). Access to this third shift will bevia combination 32 SSSSS, or by anyother selected code operating either inletter shift or figure shift, or both shifts.This three-shift facility would enable afull alphabet of capital and small letters,numerals, symbols and punctuationmarks to be printed from a 5-unit input.It will also accommodate the largealphabets required by some accentedlanguages, and by data processingsystems.A 'double shift' operation is not neces-sary to gain access to the third shift asthe mechanical construction of themachine is such that any shift can beattained directly from any other.There is no provision for a full shift lockfacility on the third shift in the mechani-cal design of the keyboard.

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Automatic CR/LFAn automatic carriage-return and linefeed facility will be made available.

Combined CR/LFThe carriage return and the line feedfunctions can be combined into one keyand one combination, if required. Thecombined functions can be restricted toone shift if need be.

Paper-Out ContactsProvision can be made for the paper tobe sensed after it leaves the roll andbefore it passes round the platen roller.The absence of paper at this point canbe made to operate a single makecontact which is wired out on thesignals plug.

Parallel Output (fromcode recognition unit)A special version of the keyboardtransmitter capable of generating aparallel 5or 6-wire (each with a tripsignal) output for data processingapplications isplanned as an alternative to thestandard serial output.(A 5- or 6-wire parallel output can alsobe obtained from the stunt box. Seesection headed 'Code Recognition').

Horizontal TabulationA horizontal tabulation facility isplanned. This will be under the controlof a special 'TAB' key which will lockdown and repeat .space' until releasedby a pre-set projection on a program-ming device. The programming deviceon the sending machine will thereforecontrol the format throughout the circuit.

Six-Unit OperationSpace has been left throughout themachine for additional components toprovide for six-unit operation, includingthe Tape Punch and the Tape Readerunits. This six-unit operation can extendthe maximum number of printedcharacters to 84 (28+28+28)

Parallel InputA 5- or 6-unit plus trip parallel input unitis available. This unit is located adja-cent to the keyboard transmitter andcontrols the teleprinter receiver throughthe electrical local record.

Parallel Output (fromkeyboard transmitter)A 5- or 6-wire parallel output can beobtained by serial-to-parallel conversionwithin the receiver and code recognitionunit (stunt box).

Copy HolderTwo forms of copy holder are available:a simple spring wire clip on the right-hand front face of the cover unit asshown on the illustration on page one,and the transparent plastic lecternshown above. The lectern has ahorizontal spring-loaded cursor whichserves as a retainer for messages andalso as a line guide. The whole lecternassembly can slide 5 inches to the rightif the operator requires an unobstructedview of the printing line.

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List of Units keyboard unit

main base unit

keyboard transmitter and answer back

electromagnet and selector unit

side frame (left-hand)

side frame (right-hand)

main camshaft unit link unit

code control unit (code recognition)

function unit

type carriage unit

carriage feed unit

platen unit

hours counter

manual control unit (function keys)

motor unit

layshaft (links motor to main camshaft)

dashpot unit

tape reader unit

tape punch unit

tape punch drive

arm assembly cover unit

signals RIS unit

Model 444 Block Diagram (facing page)note 1 Print suppression lever inhibits print action on functions.note 2 Carriage feed trip lever inhibits normal trip to Feed unit on functions.note 3 Function unit provides power to execute functions.

Creed & Company Limited • Hollingbury • Brighton • England • Telephone: Brighton 507111 • Telex 87169(c) 1966 by Creed & Company Limited Creed policy is one of continuous improvement and the right is reserved to revise equipment specifications and details published without prior notice

CREED PUBLICATION 041-033-1E Printed in England