REF ID:A39568 

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Declassified and approved for release by NSA on 01-26-2015 pursuant to 

E.O. 13526 
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REF ID:A39568 

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larch 12, 19.36 

llod1ticat1oa 1n ConYerter '7Pe 1.1-134-Tl 

(u. a. ?at•t 2,0!8,772 or le.fttllliry 2a, 1336) 

1. In O'. s. Pat.en\ 2,023,772 th• c1pher1na ooaautator 1• atarted 

and stopped, •• controlled bf the openin1 and oloa1ng or the 00111"•rlnc 

oirtNlt (coaμoaed of the nt. or ten oon"-ct leYera and associated twav 

contact points). Since tbe latter ia controlled_. the o1;>her-lt.;y tape, 

the act.loa ot the C01111Utator 11 ve17 irregular. 11.nce the inertia ot 

the eo-utator la oonAdR&ble, 1t is clitflcult to apeed. U_;l the operation ot the 17atec ad still be able to ato; the comutator rap1dl7 and 

accurat•lJ 1n 1t1 dia_rllac•enta. 

2. lheD the 1n41oatlna deYicea are glo• luapa it is or courH 

eesentJ.al either to •tot> tile C01111t1tator long eaoup tor the er• to perceift the obaracter 1llua1nated :ln the indioat1111 lank or to ,?l'oTid• a 

qatem ot Mlt-locklnc relays 1n aeries with each 11.ow la!!\,) so that. it 

a alow i.,.J> rece1Tea a aoaentaey ia;mlae through it, the aell-lock1nt 

relq acta to keep the lup 1lluainatecl lons eaough to pendt or noting 

th• character 1llu111nated. In either oaae this would ooapl1cate the 

aeahania. 

3. I haft oorsce1Te4 ot a aethod of O_;:)eration which not onq OTercoaea the torego1ng obJect1on1 ud d111&dY&nta1e1, bat. alllO aiapl1t1ea 

the 17etea co1U11derabl.7 aad at the aaae tiae ai11plitiea automat.io recording of the resultant•. 

4. The baa1c principle ot the aodif'ication is aa follow•s lutead 

or •PlOJinl the comparing c1l"cu1t to control the atart.ing and atopplac 

of the commutator wheel, let the wheel be k•t't 1n conataat, regular rotaUon, and let the ooaparina circuit. aerel.J deteraine when electric ,t>oteatial 1a applied at the kqboard. Thus, wbea a k417 ot the k97board ia 

depnaaed no current reache1 the indicating bank through the cipher coaautator until the com?Arin& circuit 1a completed. Since the latter 

nent ia controlled bJ" tile oipb•r-kef transmitter, it is obvioua that a 

reeult •ill be 1ndicatecl on tile 1Ddlcat1ng bank once per reTolution of 

the coautator, but the uaot inetant when it will be indicated ia a 

tunct1on or tile character on the ci;>her-kq ta.1.)e. U the ti• req111re4 

tor one ooat>l•t• reYOlution ot the ci~)her co1D11Utator ia resarded. •• 

being divided •i> into 16 equal intel'ftla, the ci.Jher-kq ta,,• Mrelf deterainea at which ot the 26 inter'ftlla the C'•tl&riaon circuit will be 

coa,leted aad therefor• which or the 26 poaaible equivalenta •111 be 
. .. .. • 

REF ID:A39568 

a ,~·nE:t-'..,.\ \or-

., -CGf!rlu11 i ,, ·~ 

1nd1aated tor the ke7 being de;reased. during that reYolution of the c~tator. Sina• tbia action can take place instantaneous]¥, the 

ooautator can be rotated quite rapid.17, and tbouch th• ci,;>her1n1 

action 1• irregular in that aucceasi•• enci~lhenutDte take place at 

irregular instant• ot the 0701• ot rotation within successive r8'Yolut1on• of the C01111Utator, the action 11 ato ra1)1dq perfomed that the 

operator doea not. notice the 1rreplar1v, and a cadence in keyboard 

operation 1a .,Jertect.ly poesi ble. 

s. The llOCU.t1ed circuit arra!Jl•enta are shown in accompa~inc 

Pig. 1. 

6. Obviousl.y', tor thla t7pe or control, glow 11.11p 1ndioat1ons 

are not suitable becaUBe the action 1s too rapid; or it tt is stowed 

down, one loaea ao•t of the advantages or this aoditicatioa. The 

.,ates ia much more suited to automatic recording, by controlling the 

keyboard ot an aaaoc1ated. ty,c)ftriter, or the ;.irinting action ot • rotating t"Jpe wh .. l. 

7. It a rotaUna t7pe wheel is uaed, t.he coa;>ar1aon circuit, in 

addition to 1nclud1na in series r.ith it '!ta tape-step,?ing :aagnet, would 

also include the reia, controllina the time of delivery of the ?rinting imJ:)Uls~. The t7pe wheel 1•ould hDve to be rotated qnchronouel7 with 

the cipb~r who~l. 

11ll1aa l'. J'riedaau. 

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