Модуль ввода-вывода МПС. Совмещенная карта. Адресный селектор. Порты ввода и вывода. Одноразрядный порт, страница 2

                                                                                                                                                                                                                                                                                                                                                                                   A0                           CS 01H                                                                                                                                                     1                                                                                                                                                                                                                                                                                                                                                          A1                          CS 02H                                                                                                                                                     1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            A2                                                                                                                                                                                                        CS 04H                                                                                                                                                       1                                                                                                                                                                                                                                                                                                                                                                                                              

A7                       CS80H

              1                                       

 

МП может прочитать данные из порта только в определенные моменты времени (когда    IOR=0 ).

Только в эти моменты данные из порта должны поступать на ШД, В остальное время выходы порта

                в 3-м состоянии  (IOR=1,CS=1) .Особенностью порта вывода является то, что входы порта подключаются к ШД ,принимая информацию от ШД только кратковременно , когда (  IOW=0,CS=0    ), При этом полученные данные должны запоминаться ( фиксироваться в порту вывода ). Повторное изменение содержимого портов осуществляется при новом выводе данных в порт.

Порты вывода не должны иметь третье состояние ,                          KP580ИР82

 Порты ввода ,а),                                                                                            ИР83            ШД   

                                                                      ШД          б),

DI      RG      DO     DO                                   DI     RG       DO

                                 0                     0                                                0                    0                                                                    

                                 1                     1      D1                                      1                   1

ОТ ВУ                                                             ОТ ВУ

                                                                D7                                      7                     7