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File List  |  1987-09-25  |  3.3 KB  |  91 lines
  1. PAL16R6
  2. PAL FOR NSC810 TO PC BUS INTERFACE  J.R. DRUMMOND 4/2/87
  3. CONTROLS BUS ACCESS
  4.  
  5. CLK /BS   /IOR   /IOW  RESET  A4    A3     A2    A1    GND
  6. /OC SELB  ADENB  ALE   RDB    WRB   DATENB RES   READY VCC
  7.  
  8.  
  9. IF (VCC)    /SELB  =    BS * /A4 * IOR  +  BS * /A3 * IOR
  10.                       + BS * A4 * A3 * /A2 * /A1 * IOR
  11.                       + BS * /A4 * IOW  +  BS * /A3 * IOW
  12.                       + BS * A4 * A3 * /A2 * /A1 * IOW
  13.  
  14. IF (/SELB)  /READY =  RDB * /WRB * /ALE  +  DATENB * /RDB * WRB * /ALE
  15.                       + DATENB * RDB * WRB * /SELB
  16.  
  17.             /RES    :=   /RESET
  18.  
  19.             /ADENB  :=            DATENB * RDB * WRB * ALE
  20.                        + ADENB * DATENB * RDB * WRB * /ALE
  21.  
  22.  
  23.             /ALE    :=  /DATENB  +  /WRB  +  /RDB
  24.                         +  /ADENB * DATENB * RDB * WRB * /SELB
  25.  
  26.             /RDB    :=  /ADENB * DATENB * RDB * WRB * /ALE * /SELB * IOR
  27.                       +  /RDB * WRB * /ALE * /SELB * IOR
  28.  
  29.             /WRB    :=   /ADENB * DATENB * RDB *  WRB * /ALE * /SELB * IOW
  30.                       +   ADENB * DATENB * RDB * /WRB * /ALE * /SELB * IOW
  31.  
  32.             /DATENB :=  RDB * /WRB * /ALE
  33.                       +  /DATENB * RDB * WRB * /ALE * /SELB * IOW
  34.                       +  /RDB * WRB * /ALE * /SELB * IOR
  35.  
  36.  
  37. DESCRIPTION
  38.  
  39.                      ------u------
  40.           CLK      1-|           |-20     VCC
  41.                      |           |
  42.           /BS      2-|           |-19     READY
  43.                      |           |
  44.           /IOR     3-|          R|-18     RES
  45.                      |           |
  46.           /IOW     4-|          R|-17     DATENB
  47.                      |           |
  48.           RESET    5-|          R|-16     WRB
  49.                      |   16R6    |
  50.           A4       6-|          R|-15     RDB
  51.                      |           |
  52.           A3       7-|          R|-14     ALE
  53.                      |           |
  54.           A2       8-|          R|-13     ADENB
  55.                      |           |
  56.           A1       9-|           |-12     SELB
  57.                      |           |
  58.           GND     10-|___________|-11     /OC
  59.  
  60.  
  61.      ADEN DATEN RD WR /ALE
  62.  
  63.   +->  1   0   0   0   0
  64.   |              |
  65.   |              | BS * IOW + BS * IOR
  66.   |              |
  67.   |    1   0   0   0   1
  68.   |              +-------------------------------+
  69.   |              |                               |
  70.   |              |  BS.IOW                       | BS.IOR
  71.   |              |                               |
  72.   |    0   0   0   1   1               0   0   1   0   1
  73.   |    0   1   0   1   1                         |
  74.   |              |                               |
  75.   |              |                               |
  76.   |    0   1   0   0   1 <-+ BS * IOW  0   1   1   0   1 <-+ BS * IOR
  77.   |              |         |                     |         |
  78.   |              +---------+                     +---------+
  79.   |              |                               |
  80.   |              +-------------------------------+
  81.   |              |
  82.   |    0   0   0   0   1
  83.   |              |
  84.   +--------------+
  85.            WRITE CYCLE                 READ CYCLE
  86.  
  87. READY ASSERTED AT LOOP POINT IN BOTH CYCLES AND BEYOND
  88.  
  89. ADDRESSES 00000 -> 11001 ARE DECODED
  90.