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<br />. . � .. . � . . � �. . 3�, -
<br />� � .� � . - . . � � �a�:
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<br />EX PLA � ATI 0� Q F R E G I STE �tS �P'��915��r Functions as the program address ,;�;
<br />counter. Provides continuity between: individual.'
<br />steps of }�rogram by generating the addresses at � ':
<br />s;
<br />which individual steps are contained. Upon comple-
<br />tion of each sequential step, count in P is advanced '
<br />by one to specify address of next step. Jump instruc-
<br />tions clear P and enter new address in it.
<br />*Index Registers, �'-86 Provide modification af
<br />e�ecution addresses in program loops. Contcnts of an
<br />Index Register can be advanced each pass through
<br />' * a t�op, with an exit initiated on a given threshold.
<br />A-F�egister Principal arithrnetic register. Func-
<br />tions as a 48-bit accumulator in most arithmetic �ltcrnate approach allows an Index Register to be
<br />operations. Quantity zero represented by a binary preset, then rcduced by one count each pass through
<br />zero in each sta�e. Cantents of A may be shifted the �rogram—with an exit after zero.
<br />� - either to the right or left. Shifting may involve only Storage Address Registers, S'-S2 Represent -
<br />the contents of A or may include the conte:�ts of Q. even and odd 16,384-word zr�e��iory units respec-
<br />r� : Leftmost sugn bit extended on shifts to right; bits tively. Receive addresses of instructions from P and
<br />;,..
<br />shifted ofi' the right end of A or Q are dropped. Lcft addresscs of operands from U2.
<br />`��� � shii'ts are circular, with lower order bits being re- Storage Restoratian Regisfer�, Z'-Z2 Represent
<br />�` placed by higher order bits. Multiply, divide, and
<br />� even and odd 1�i,384-word memory units respeo-
<br />€loatin� point instructions are sequence� operations .
<br />involving botli A and �„?. tivcly. Hold th� 48-bit word to be wr� tten in a given
<br />storagc locacion.
<br />*Q-E�egister Assists accum�ulator in performing
<br />R-Register Functions as exchan�e rc�istcr for
<br />more complicated arithmetic operations. Used with
<br />�.� " A ta perform double precision arithmctic. Qmay be transmission involving Ii-Index Registers. Used in
<br />shiftcd right or Ieft, singly or in conjunctian with A. advancing or rcducing count in a given B-Register.
<br />lluring sevcr�,l instructions, used to count repetitive
<br />.: Q alao eontair�s mask in Iogical oJaeration. operations. R used with floatin� painc iizstructions _
<br />Program �Cantrol Rsgister,U' Holds prograrn step in performing arithmetic aperations on the expq- •:
<br />whilc tl�e two insu•uctians containcd in it arc e�ccut- nent or ch�ractcrisiiG.
<br />'= ed. Thc 48-bit itistruction wnrd taken from storagc
<br />, K-Register An cxchangc and auxiliary arithm�-
<br />, �ocation s�ecified by P and entcrcd in U', thc upper tic rcbistcr. All input-aut�ut data passes t��rough X. :
<br />�,: instxuctian being executed firsc. �xcc��tian of lower
<br />,,, ' instr�,ction follows, ea�ept whcn u�per insrruction Externaf �unclior� R�gist�r, 0° Used far ex-
<br />;��.- is a jump or whcn it pt•avides for conditional sk' �- changing contr�l inCormacion with input-output
<br />' ping of lower instruction. �quipmcnt.
<br />Auxiliary Program Gonirof Register, 61� An ac- Output Rsgisiers, 0' thraugh U'' CO' thrnu�h 0'
<br />cumulator used in the modification of execution used for output buf�'cr operations whcrc data is
<br />� a�lcire�.� o#' current instruction. This modification transmittcd ar specd of input-output equipm�nt. `; '�
<br />� consists of addin� contcnts oi an Inde� �Zegister to Wlierc higia-specd transfer is rcquired, output tr�ns-
<br />, execution address of curr ent instruction. fer nperations carricd out via Qg. 4,
<br />*Opera�ional Registers
<br />,
<br />, ;,
<br />:;
<br />, �
<br />, ; � P.�
<br />y. . �. . . . . , . � . . �
<br />t �� �a S � . ' �. . � � . _ 1 ��.
<br />� � ' l�
<br />�it� y.: � � � : ts
<br />C.t�Nti�','r`;� u ��, , �t�'ti k^�,n� � ` ^ ' - -- - . . . � . .. .. . � .. , _. . , .. . , t ._. . . ., _.� , , � ,- . .',t�'�r rt ai ,�, �*(u,�
<br />
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