TO 

REF ID:A71ia2 

.._, 

AJU,I?~nTOtr HALL STATION 

Date ------ Fll>H 

--~Comm.anding O.f'ticer ______ _ 

Executive Ofticer --Asst. Executive o-n-1-c_e_r ____ _ __ Jt.djutant,__ _________ _ 

JaSSt. J\C.(jutant 

--Cl :ie f B Section ------------ f7 ~e C Section h Cot. C. ,,f .. C • ef, D Section --- __ Cl def / E Section_. --------- ______ _ 

Cl.ief, 1'' section 

-o.o. ot Trbops --------

Dir. ot Com. Jti&earch 'WuL. B;M --Pe'rsonnel Officer ----U• ---'}uartormaster ---Provost Harsh_,il ________ _ 

-lPile Roon ---- .... ________________ _ 
1111-¥1032- ... 

IN RllPLY RID'lllt. 'IO WAR DEPARTMENT SPSIS•3 

SPSIS.461 Codes OFFICE OF THE CHIEF SIGNAL OFFICER 

WASHINGTON 

Subject: 

'l'o: 

Use of SIGABA in Canjunoticm with Standard 

IBM Codat,pe Units. 

Colonel Cook 

Jlaroh is. 1943 

1. A demonstration was held at Arlingtcm Ball Statian. M'.aroh 16• 

1943, at l·~ with tbe tollaring perscma present: Major Kulm, lfa.jor 

Roaen, Captain Cooley, Captain Giles, Lt. Hardie, Lt. Shinn and 

Mr. A. c. Holt of Interna.tianal Businesa Machines, Ino. 

2. In order to set up this equipment tor experimentation the 

following obangea in the SIGABA 119re neoeasar71 

a. Clutch !rip Maga.et operatian (exclusive of tbe look-up 

oirouTt) ta.ken an7 tram the SI GA.BA print circuit and given to the 

IBM Operating Unit. 

b. •3'/'/ ohm. resistor inserted in aeries w1 th the SI GABA print 

oircuTt to CClllpensate for change !.• 

c. •Double-pole double-throw toggle switch inserted in the above 

cirouTts to provide tor operatiaa. with the IBM equipment or tor normal 

independent SIGABA operation. 

s. Aa a result of tbe above changes it is poasible to take radio 

type tape directly tram the enciphering operation. ot the SIGABA as 

•11 a.a getting a page copy of the enciphered :message eliminating the 

necessity tor pasting up tape. en deciphering, radio type tape ia 

taken directly tro.m the radio circuit el1.minating the retning operat:l.an.. Decipherment is autC1D&tic ttirough the SIGABA giving a page oopy 

of the clear text eliminating the pasting operation.. 

4:. Daring the dem.cm.stratiaa. the following obaerva.tima •re 

made: 

a. Jlaohin.e haa a rumdng speed ot tram 2s; to nj characters 

per mTnute Oil autCID&tic cleoiphennant. 

eclassified and approved for release by NSA on 07-02-2014 pursuant to E.O. 

3526 

• Standard TeletJPe SIGABA Parts 
SPSIS.461 Cod.ea 

(Mar. 18.1943) 

b. The maohine oan be run steadily tor eight hours whereas e'V'9Jl a 

good 'Opera tor oould not operate a SI GABA staadil7 for tba t number of 

hours. 

o. An operator would ordinaril7 be required to sit at the maohin.e 

therel'ore it would not reduce need tor persannel. 

d. It does not take any langer tor a good ID8D to paste up tbe same 

length message. Also any addi ti ans or deletian.s can be made by the clerk 

mider normal independent SIGABA operatian whereas en the machine changes 

cannot canveniently be made • 

.!• It is aubject to the normal errors in tape and messages. 

t. There is a cansiderable amount ot equipment tied up which oould 

better be used elsewhere • 

.1• Wiring changes w011ld have to be made in any SIGABA used in 

can.junction with this set-up. 

h. About the only argument tor the machine ia the time saving 

factor. and that seems queaticnable. 

1. An actual teat oan be determined cnly by placing the machine 

in thi' Code Center worlc1ng under heavy 'traf'f'io ocm.ditio.ns. 

SE&l\El 

- 2 -

~~ ..... ,-'~~-~-...... 

Frank B. Rowlett• 

Major• Signal Corp a