
   ஫ אַ 㯠  

    ஫  אַ 㯠  
(,  DMA - Direct Memory Access) -
稢  ᮪᪮⭮  묨
  ன⢠  -뢮   
 ᯮ짮 業ࠫ쭮 -
,     ᢮ 
  믮 ᫥ ࠫ쭮 
    ᨬ  . 
     ᯮ 
ࠡ   ᪮묨 ⥫ﬨ, 
ॠ ᯮ짮  ࠬ
⥫    ⭮   冷
㣨  ன. ⨬ ਥ⢠
 ᯮ짮    
  ன⢠,  ਭ騬  -
騬   筮 訬 -
ﬨ  ᮪ ᪮.
      PC-    㭪樨
஫     믮  奬
8237     INTEL  (ᮢ᪨  
181037)        8237-4 
8237-5,  ࠡ騥  ⠪⮢ ⮩
4    5   ᮮ⢥⢥ (⠭⭠
奬  8237  ࠡ⠥   3
). ஫  4 ᨬ -
,       㦨-
  ਩ ன⢮.

   1. ਭ樯 ࠡ ஫ 

      ࠡ   ࠧ 2 
横: 横  (Idle cycle)   -
⨢ 横 (Active cycle).   横
ࠧ     ﭨ, -
    ६  ਮ ⠪⮢
  (⨪).   横  -
஫    ॢ  ﭨ
ணࠬ஢   (Program   Condition)
⥬   室 RESET ᨣ -
  ஢, ⥫쭮   300
c    ᫥饩      ᨣ
  ஢  (஢  0)  뢮 CS
(Chip  Select).  ﭨ ணࠬ-
  ஫ 㤥 室  
,   뢮 CS ࠭   ᨣ-
   ஢.   ணࠬ-
஢ ஫ :

    - 砫      -
;
    - 㬥襭   ᫮ -
 ⮢;
    - ࠢ ,

 ⠪ ⠭ ॡ㥬 ०
ࠡ  (ࠧ    横-
᪮  ਮ⮢, ⮨-
,    ࠢ 
    . .).
    㧪    16-ࠧ來   ॣ஢
஫  ⢫ १ 8-ࠧ-
來  -뢮. । -
   ࢮ  (襣)    
  襭  (饭)  ਣ-饫
(ਣ   /᫥,  First/Last
flip-flop),   ᢮   -
ﭨ ᫥ 뢮   ࢮ 
 ⠪ ࠧ   ᫥-
饩  뢮     -
  訩   ᮮ⢥饣 -
.
    ணࠬ஢   
᪨஢  ( ᪨  ⠭-
    ⮬   0), ᫥ 祣 
   ਭ   ᨣ  "  
", 㥬 ⥬ 譨 ன-
,  ஥  㦨  १ 
.    "    "  
  ⠪  樨஢ ⠭   1
        ॣ
ᮢ  ஫.  ᫥  
ᨣ   ஫ 室  -
⨢  横,  ஬ 믮  -
  묨.   ⢫
    ०:
    1)   筮 । (Signle
Transfer  Mode). ᫥  横 -
।  ஫ ᢮ 設 -
,    ࠧ  稭 ஢
ᨣ  ,  ⮫쪮 㦨-
 ⨢ ᨣ , 樨
᫥騩 横 ।.
    2)    筮  ।  (Block
Transfer  Mode).    ⮬ ० 稥
ᨣ   ॡ ⮫쪮  -
 뤠 ஫஬ ᨣ "-
ত    " (DACK), ᫥
祣 設  ᢮   -
襭 । ᥣ .
    3)     ।    ॡ
(Demand  Transfer  Mode).    ०
  ஬   -
묨:  ।    뢭  
,    ⨢ ᨣ , -
ﭨ ண ஢ ᫥ -
 横 ।.  ⮫쪮 ன⢮
    த  ।,  ᨣ
  뢠      ஫
ਮ⠭   ࠡ.     ०
ਬ         묨
ன⢠,    騬  ᢮
६ ࠪ⨪ ࠡ  
 ० 筮 ।.
    4)  ᪠  ० (Cascade Mode).
       ⥬
    ஫   -
,  筮  
.  ⮬ ०    -
饣 ஫ ᯮ    -
஢      ஫஬   ண
஢.   ࠡ  ᪠ ᨣ HRQ
("  墠")  ஫-
   室 DREG ("  -
   ")   饣,    ᨣ  DACK
("⢥ত ") 饣   -
  室 HDLA ("⢥ত  -
") .
      奬  祭 筠
祭  饣 (ࢮ) ஫-
    ய,     
 ᨣ HRQ  HDLA.

            2.  ।

       2.1. । -
         (Memory-to-memory DMA).

    ᯮ      ।  
       㣮.
室   ।  ॣ
㫥  , 室 -  ॣ
ࢮ   .  ᫮  横  
(᫮   1)   ॣ
᫠ 横  1. । ந-
    ᯮ짮 ࠡ祣 ॣ
஫    ⢥  ஬筮
  ࠭ ଠ樨.  -
e -    ᯥ-
樠  ० 䨪樨  (Address
hold),    ஬  祭  ⥪饣
    ॣ  㫥   
,   ⮬  室 
      ⥬  -
⮬  , 室騬  
.

        2.2. ⮨樠
   (⮧㧪, Autoinitialization).

    ᫥  襭  筮  ।
ᯮ짮     ᪨ 
  ९ணࠬ஢  -
襩 ࠡ  .  ⮨樠-
樨  ᪨஢    ᫥ 砭
।  ந室,  ॣ ⥪-
饣     稪 横 ⮬-
᪨   㦠    ᮮ⢥
ॣ஢  砫묨 祭ﬨ. 
ࠧ  த (७) -
 筮 ⠢ ᨣ 
    .

  2.3.  䨪஢ ਮ⮢.

      ⮬  ०  0 ᥣ 
ᨬ ਮ,   3 -  -
.  砥,   -
     ᮪ ਮ-
⮬ 㤥 믮 ࠭, 祬  -
    ਮ⮬.

  2.4. ᪨ ᤢ ਮ⮢.

       "" 設
   ६ ।e
  ᪮쪨  .  ,
  ஬  諠 ।, ⮬-
᪨  ᢠ  訩  ਮ,
᫥  祣  ࠢ   । 砥
  訬 ਮ⮬,  -
ண  ।    .
  ࠧ,  ᫨    砫  ࠡ
।  ਮ⮢  뫮 
(  0 - 訩),  諨 ᨣ
      1-  2- ,
  ᭠砫  㤥  믮 ।
  ࢮ  ,  ⥬    
訩  ਮ (  2, ᮮ⢥-
,  訩,  . . ᤢ ਮ⮢
横᪨)    ।  믮 
2-  ,  ⥬  -
訩  ਮ,  訩 ਮ -
,  ⢥⢥,   3,  
㤥    २⢥ ࠢ
 ।.

      2.5. ⨥ ६ ।
      (Compressed transfer timing).

     砥, ᫨ ६ ࠪ-
⨪  த⢨  -
ன  ᮢ,     ᮪
६  믮  ⠪ ।
 2 横 ⠪⮢    ⠪-
⮢ , 室   横 -
।.

  3. ᠭ ७ ॣ஢ .

    ஫  344  ७
, ࣠   ॣ஢.
ᠭ ७ ॣ஢  ਢ-
  ⠡.

Ŀ
                        來     ᫮   
            ॣ                   ()      ॣ஢ 
Ĵ
  砫쭮               16            4     
 (Base Address Register)                                    
  砫쭮 稪 横     16            4     
 (Base Word Count Register)                                 
  ⥪饣                 16            4     
 (Current Address Register)                                 
  ⥪饣 稪 横       16            4     
 (Current Word Count Register)                              
 稩 ॣ                  16            1     
 (Temporary Address Register)                               
 稩 ॣ 稪 横        16            1     
 (Temporary Word Count Register)                            
  ﭨ                      8             1     
 (Status Register)                                          
                           8             1     
 (Command Register)                                         
  ० (Mode Register)         6             4     
 稩 ॣ                        8             1     
 (Temporary Register)                                       
  ᮪ (Mask Register)          4             1     
  ᮢ                       4             1     
 (Request Register)                                         


      3.1.  砫쭮 
         (Base Address Register).

      ⮬  ॣ  ⮢
 ,  ண 稭 ।-
.  ᮤন 16 ࠧ冷  -
      -
 ࠧ஬ 64.   
  ⢫ १ ᯥ樠
ॣ    (Bank Registers), -
ন  譥 .  -
      ᢮ ॣ 砫쭮
    ॣ  .  
     ⢨
      , 室騬 
祭    .    
⮨    ࠭  稭
  ࠭  ஬,  4 (0, 1,
2, 3; 8, 9, 10, 11  . .).

 3.2. 砫쭮 稪 横
      (Base Word Count Register).

      ⮬  ॣ  砫쭮
᫮  横 ।  ணࠬ-
  .  ᪮ ᫮ ।-
    ६  ࠡ   ⮢
      ॢ蠥  
᫮  横, . . ᫨   100
横 ।,  ࠧ  㤥
ࠢ  1 ,   ᥠ  㤥
। 101  ଠ樨.

      3.3.  ⥪饣 
       (Current Address Register).

    砫쭮  祭   
ॣ ६  ॣ஬ 砫-
 .  쭥襬  室 ।-
 祭 ⥪饣  ⮬-
  㢥稢  㬥蠥 (-
⭮  ࠢ    
 ணࠬ஢  ॣ ०).
᫨   ࠧ襭  ⮨樠,  
᫥  砭 ।  ॣ  -
⮬᪨  ⠭ 祭 
ॣ 砫쭮 .

 3.4.  ⥪饣 稪 横
     (Current Word Count Register).

      ᮤন  ⥪饥  祭
稪 横 (᫮ ⠢ 横
।). ⮡ࠦ   ᫮ 横-
  ᥣ     ᫠ 
  । ⮢ , ⠪ 
 祭  ⮬ ॣ ந-
   横 ।, 㦥 -
 䠪᪮ ।  ,
    ।  䨪  
९   稪  (  
祭  0  0FFFFh).

          3.5.  ०
            (Mode Register).

      ॣ  ० ࠡ
᢮  ஫.

 7 6 5 4 3 2 1 0
ͻ
xx      
Ѽ   ᪫ ⮢:
              
          0-1:  ࠡ:
                00=( )
                10=⥭( )
                11=⨬ 
         2: ⮨樠:
                 0=饭
                 1=ࠧ襭
        3:  ⥪饣   :
                  0=㢥祭
                  1=㬥襭
      4-5:  ।:
                    00=० ।  ॡ
                    01=० 筮 ।
                    10=० 筮 ।
                    11=᪠ ०

          
᢮    ॣ஢, ᠭ  .
஬ ⮣,   ᫥騩  -
஢,    .

          3.7.  
          (Command Register).

 8- ॣ  ࠢ ࠡ⮩
஫.   ணࠬ,  
஫ 室   ﭨ  ண-
ࠬ஢  頥  -
 "Reset"  "Master Clear".  祭
⮢  ॣ   ਢ  -
㭪.

 7 6 5 4 3 2 1 0
ͻ
        
Ѽ   ᪫ ⮢:
            
         0:0= । -
             1=ࠧ
        1:0= 䨪    0
              1=ࠧ
       2:0=ࠧ஢ ஫
               1=஢
      3:0=ଠ쭠 ६ ࠬ
                1=ᦠ⨥ ६ ।,
                  ᫨  0 ⠭,  
     4:0=० 䨪஢ ਮ⮢
                 1=२ 横᪮ ᤢ ਮ⮢
    5:1=० ७ 
                  0=প  ,
                    ᫨  3 ⠭,  
   6:0=⨢ ᮪ ஢ ᨣ 
                   1= DREQ
  7:0=⨢ ᮪ ஢ ᨣ
                      ⢥ত   (DACK)
                    1=



         3.8.  ﭨ
           (Status Register).

      ࠦ  ⥪饥 ﭨ
ᮢ  ।   ᥬ  ६ -
.  0 - 3 ⠭  -
 ᫥ 襭  ।  -
 0-3 ( 0 -  0,   1 - 
1  ..), ᫨   ०  ⮨-
樠樨.        ᫥
   ஫  ᫥ -
 樨 뢠 ﭨ  -
  ﭨ.  4-7 㪠뢠 
   0-3 ⨢   ⥪騩
 ᨣ   .

            3.9.  ᮪
             (Mask Register).

      ⮣ 4-⮢ ॣ
᪨/᪨ ᢮  ,
⮬ 祭 1 ᪨ ,祭
0 ᪨     ࠧ蠥  ਥ
ᨣ   ⮬ .

         3.10.  ᮢ
           (Request Register).

          (DREQ) 
      㦨  ன-
⢮,⠪  ணࠬ.  ணࠬ
 ᨣ     4-
       室   ⠭
ᮮ⢥騩     4-ࠧ來  -
 ᮢ.    
⬥     㫥  祭  
ᮮ⢥騩  ॣ.  -
 頥 ⮬᪨  砭
।      .   
ᮢ    ஫-
.   ⮣, ⮡ ਭ  ண-
ࠬ   ,   -
室  ० 筮 ।.

          3.11. 稩 ॣ
          (Temporary Register).

     8-ࠧ來 ॣ ᯮ-
  ࠭  , ।-
   ०  䨪஢ 
  । -   -
 ࠭ ।  
 ⠫ ० 
।.

        4. ணࠬ ࠢ
             ஫஬ 

    ணࠬ  ࠢ ஫஬
 ⢫ १  --
.    ॣ ஫-
    ⢫  १ ᢮
 -뢮.
     ⠡  ਢ ᠭ ⮢
-뢮, ।祭  ࠢ-
 ஫஬ .  ⠡ 㪠
⮫쪮 訩  , 訩 
   ⮢    . 
ࠢ #77.

Ŀ
Ⳑ                祭                         
Ĵ
#0C 쳇 砫쭮   ॣ 砫쭮     
            ॣ ⥪饣   0         
#2C     1                                
#4C     2                                
#6C     3                                
Ĵ
#0C ⥭⥭ ⥪饣   ॣ ⥪饣       
            0                                   
#2C ⥭⮦   1                                 
#4C ⥭⮦   2                                 
#6C ⥭⮦   3                                 
Ĵ
#1C 쳇  ॣ 砫쭮 稪 横     
          ॣ ⥪饣 稪 横  0         
#3C     1                                
#5C     2                                
#7C     3                                
Ĵ
#1C ⥭⥭ ⥪饣 祭  ॣ ⥪饣     
          稪 横  0                          
#3C ⥭    1                                
#5C ⥭    2                                
#7C ⥭    3                                
Ĵ
#8C 쳇 ॣ                          
#8C ⥭⥭ ॣ ﭨ                      
#9C 쳇  ॣ ᮢ                      
#AC 쳇  ᪨            
#BC 쳇 ॣ ०      
#CC 쳎⪠ () ਣ-饫(ਣ ࢮ/
          ᫥)                                       
#DC 쳏ணࠬ  ஫                     
#EC 쳎⪠ ⮢ ᮪  4-               
#FC 쳇 ॣ ᮪   4-         
#DC                                                         
 ⥭⥭ ࠡ祣 ॣ                       
#FC                                                         
Ĵ
#07 쳇     0                 
#17     1                                
#27     2                                
#37     3                                


     #0C-#7C ।祭   -
  室  祭   ॣ -
砫쭮  ⥪饣 , 砫쭮 
⥪饣 稪  横     4-
.     쬨ࠧ來,
 ॣ,   १  -
   ,  16-ࠧ來,     
ந    ਥ. । ࢮ
 뢮  ॡ㥬  -
   ਣ-饫,  祣
믮  뢮 ந쭮
祭   #CC, ᫥ 祣  ॡ-
  뢮 訩  16-ࠧ-
來  祭  ⥬  訩  
᫥饩  뢮   
 .
    뢮    #8C   
祭  ॣ    (ᠭ
⮢ ॣ  ਢ  .3).
    ⥭      #8C 뢠 -
 ﭨ  (ᠭ ⮢  -
 ﭨ ਢ  .3).
        #9C  ⠭-
       ॣ
ᮢ      . ଠ
 ᫥騩:

 7 6 5 4 3 2 1 0
ͻ
xxxxx        ᪫ ⮢
Ѽ     
             0-1:롮  00-0
                                   01-1
                                   10-2
                                   11-3
            2: 1=⠭    
                      0=    

        #AC  ⠭-
     ᪨   ॣ
᮪        .  ଠ
:    

 7 6 5 4 3 2 1 0
ͻ
xxxxx        ᪫ ⮢
Ѽ     
             0-1:롮  00-0
                                   01-1
                                   10-2
                                   11-3
            2: 1=⠭  ᪨
                      0=  ᪨                                 

       #BC ⠭ -
祭   ॣ ०    4-
 .  0  1   -
(00-0, 01-1, 10-2, 11-3).   2-7
  祭,  । ᮮ-
⢥    0-6 ॣ ०.
(ᠭ ⮢  ॣ ० ਢ-
  .3).
       #DC  ணࠬ
 ஫ (Master Clear).  뢮
          
⦥  䥪,       
஫.  ணࠬ  -
 ॣ ,ﭨ, -
ᮢ  ࠡ稩 ॣ.  뢠-
 ਣ-饫   ᠭ 
 ᮪  ॣ ᮪. ᫥ ண-
ࠬ    ஫ 室 
横 .
    뢮     #EC 頥
ॣ ᮪-뢠   -
    ⠪ ࠧ ࠧ-
  ਥ  ᮢ    ᥬ -
.
    १   #FC    ந-
쭮  祭  ॣ  ᮪  .
 ⮣ 室   0-3 ॣ-
 A ⠭ ॡ㥬 祭 ᮪
 0-3 ᮮ⢥⢥  뢥 
祭  .
          ।祭
    ,  -
ன 㤥 ந . ஬
    訥    
࠭, 稭  2 . ,
  ⥪    ࠡ
⮫쪮     ࠧ஬ 64, 
, ᯥ稢 ४祭 -
 ஥ ⠪,     -
 ࠭, ᠭ  . - ⮩
ᮡ        
⢨     , -
ᥪ騬 ࠭     ⠪
.     ᢮ -
 , ⮬    -
 ᨬ    㣨 -
,      ⮢  ࠭筮  
(#7FFD, #DFFD, #1FFD  ..).

