KCMX will delay the sampling for 300 µsec. If the enter signal is still false at the completion of this time period, the KCMX will return a data word of all ONES to the computer for that address. If at any time during this delay the enter signal becomes true, the KCMX will sample the data and gate the data into the computer input register and transfer it to the computer with an input  data  request  (IDR).  The  12  data  bits  from addresses 63-71 will occupy the lower 12 bits of the computer input word. Address 72 data bits occupy the entire 30-bit word. Digital Input Channels and Digital Output Channels The KCMX is capable of receiving and transmitting data over four 30-bit CDS I/O channels (DIC1 through DIC4 and DOC1 through DOC4). The input channels are assigned KCMX addresses 73 (DIC1) through 76 (DIC4). The DIC/DOCs (figure 13-11) maybe used for input only devices, output only devices, or a DIC/DOC pair  (DIC1/DOC1,  DIC2/DOC2,  and  so  forth),  which can communicate with an I/O device. The  KCMX  DIC/DOCs  allow  the  computer controlling the KCMX to communicate with four or more digital devices. The KCMX may function as a computer   or   as   a   peripheral   device   when communicating  with  the  external  digital  devices. Devices linked by the DIC/DOCs will conform to standard  CDS  format  30-bit  parallel  transfers  using either computer or peripheral control logic signals. The DIC/DOCs themselves can be manually set to one of two data transfer formats designated peripheral (PERIPH) or computer (COMPUTE). (Both types of transfers  involve  30-bit  parallel  data.  Computers generate  function  codes,  while  peripherals  generate interrupts; peripherals generate requests such as output data  requests  (ODRs),  while  computers  generate acknowledgments such as output data acknowledges (ODAs), and so on.) In the peripheral format, the KCMX appears as a piece of peripheral equipment to an external computer. In the computer format, the KCMX  appears  to  be  a  computer  to  the  external peripheral device. The  DIC/DOC  interfaces  have  limitations. External  functions  can  only  be  transmitted  from  the controlling  computer  over  the  DOCs.  Interrupts  can only be received by the controlling computer from an external device over the DICs. Devices connected using  output  only  or  input  only  configurations  may require a DIC/DOC pair to be connected to allow both computer control by external function and device interrupt capabilities. In other words, a single DIC or DOC  hookup  loses  the  external  function  control capability   (DIC   only)   or   the   external   interrupt capability (DOC only). DIGITAL  OUTPUT  CHANNELS  (DOCs).— The cabling for each of the four DOCs is the same as that of a computer or peripheral output channel. A manual switch for each DOC selects either peripheral or computer interfacing for the device connected on that channel. DOC  Computer  Operation.—  The KCMX acts as an interface between the external device (peripheral) and the controlling computer. The KCMX accepts data one word at a time in a buffer from the controlling computer. Up to the first seven words of the buffered data  may  be  external  function  commands  for  the external equipment. External function commands sent by the controlling computer to the KCMX set up the buffer size (number of data words) and the number of external  function  command  words  in  the  buffered  data. The KCMX generates the external function signals for the  external  function  commands  setting  up  the  external equipment and then transmits the remainder of the buffered words as normal computer output data. A maximum of 255 computer words (external functions and data) may be sent by the controlling computer in a single  buffer. DOC  Peripheral  Operation.—  In  the  DOC peripheral operation format, the KCMX acts as an interface  between  the  external  device  (computer)  and the controlling computer. The data buffer from the controlling  computer  is  inputted  to  the  external computer as interrupts or data words. The controlling computer’s  external  function  commands  define  the number of interrupt words (maximum seven) that precede the data words in its output buffer. DIGITAL  INPUT  CHANNELS.—  The four digital input channels (DICs) are interrogated by the controlling computer on a regular basis. Each DIC is assigned an address (DIC1 address 73 through DIC4 address 76). If the data word being received by the KCMX is not an external interrupt or external function, the   KCMX   will   wait   until   the   DIC   address   is interrogated  before  sending  the  data  word  to  the controlling computer and indicating acceptance of the word to the external device. 13-18