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����� �S�um�nar�
<br />of �uffier 0 eratio
<br />. . ' r .:tt �- qr
<br />pn tween 1604's or between one 16Q4 and peripheral
<br />e The Model 1604 buffer control continuallv inter- equipment having comparable speed.
<br />,
<br />roga#es all communication channels to determine • Only one instruction is required for a block of
<br />if, a periplieral equipment is ready to send or input or output data. A 4$-bit word is transferred
<br />receive information. in or out in 4.8 microseconds.
<br />� If a peripheral equipment has data ready for e All transfer operations are carried out via chan-
<br />transfer, inCerrogation waits momcntarily while a nel 7.
<br />word is being buffei�ed. The bufTer control then re- �u� _
<br />,
<br />sumes interrogating the communication channels. mary of Prograr� Interrupt
<br />�Buffering initiates comm>>nication between com- �The Model 1604 recognizes an interrupt signal;
<br />puter. memory, the three 6ufier input channels,
<br />which may be either a signal indicating that a
<br />peripheral equipment has cornpleted sending or ; `'
<br />and the three buffer output channels. These buf �
<br />' � fer informaCion in and aut asynchronously with receiving in formation or it may be a fault. condi-
<br />the main computer program. tion, e.g., an overfl�w. ;
<br />�
<br />`�
<br />sA s�.',--outine determines what has caused.the in�.
<br />` The . three buffered input channels and the three ;
<br />bufFered output channels, the interrupt line, and terrupt, e.g., what specific peripheral equipment s:
<br />: the real-time clock are r�.pidly scanned by a scanner is causing the interrupt and on which channel the .'i
<br />interrupt is taking place. , r'
<br />A, which looks for action reques�:s from alI channels.
<br />TheMe action requests are initiated by the peri�heral �The subroutine takes action with the originating:; ;
<br />� : A
<br />< equipment by indicafior "flags:" A complete scan is peripheral equipment by first removing the inter-,
<br />, ,
<br />` made in 3.2 microseconds, which corr�sponds to the rlapt signal to prevent re-reco�.iition. . ��
<br />, , �
<br />phase rate af magnetic core memory. r The appropriate condition is set up in compliance �' :,'F t
<br />' When a request is detected by the scanner, the with the interrupt. If it has come from .a peri :,: __'
<br />� � �
<br />� main 'computer prQgram is halted momentarily to pheral equipment, the action is completed=a£ter : ����
<br />�
<br />move the data between merriory and the requesting Which there is a reLurn ta the main;; Gorrmputer ;: "�
<br />charinel. The rriain program proceeds immediately program. ;
<br />' ' ' . . . :��{4�i
<br />, after, this action unless the scanner detects that ., t�
<br />Su�nmary of Exter�al Fun�t�an s,� f�
<br />'' another channel has requested servicing. For exam- �����
<br />r � ` �' , . . . - , . � . . . . . � : � : , �' �. �' -... 9;
<br />pl�, �if.the` system includes:six `1607 magnetic tape eThis instruction provides control and: communl- ;` ;,;��';,
<br />; syste;ms; all three buffered input channels and aIl cation between : the NlodeT 1604 'and periplieral � `'
<br />t4�
<br />three. buffered output channels of the 1 G04 can 'op- equipment. It contains, eight sub-instructions , `
<br />" ;7�wao
<br />'x �erate:in�the.buffer mode, simultianeously servicing at which select �nd.sense peripheraTequipments, or `°`h ;;
<br />,�fu11 t�Pe-rate three 1;607 magnetic tape units oper- activate buffer channels. � ��'�¶�
<br />�: � ;�
<br />� ating,� in t�ie. read mode and three 1607 ma netic � � ,}`�� i'�
<br />g o The select sub-instruction 74.0 is� interpreted as ` �,�t
<br />1 �;tape unifis oper�ting in the write nnode: ` - ��
<br />follows (see illustration next a e' the `l�ftmc�st 6� �'�
<br />P , g ) ,.
<br />,
<br />bits are the operation code,' the next 3 bits c�esi � �� S'`i�
<br />,, � g � ���„
<br />' � 'Sumrr�ar� of Ni�h' �p�e� nate' that this is a select sub=instruction,:the nFxt 3�' �``��..��
<br />wr
<br />��`r��s��r d'9��r�}��n bits are the channel or internal condition selection `, 4'',�E���
<br />,, � �' code, the next 3 bits are the equipment selection '_''"�'�
<br />, � �' , ; � � � � � �� .�,
<br />�t �� �
<br />• Tkie mair� computer program performs the high- eode, and .the last 9 bits specify. th. e operation, for '' "F�'�
<br />, N � ��.
<br />�' ��' sp�ed 'input-output transfer of information be- the selected equipment, s��
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