PAL16R6                                             PAL DESIGN SPECIFICATION
P7082                                                   COLI/VOLDAN 04/05/82
4-BIT COUNTER WITH TERMINAL COUNT LOCK
MMI SUNNYVALE, CALIFORNIA
CLK NC  NC D0 D1 D2 D3 CLEAR /LOAD GND
/OC NC /EP Q3 Q2 Q1 Q0  NC     NC  VCC


/Q0 :=  CLEAR                     ;CLEAR Q0 (LSB)
     +  LOAD*/D0                  ;LOAD D0
     + /LOAD*/Q0*/EP              ;HOLD IF NO EP
     + /LOAD* EP* Q0              ;COUNT IF EP AND Q0=H

/Q1 :=  CLEAR                     ;CLEAR Q1
     +  LOAD*/D1                  ;LOAD D1
     + /LOAD*/Q1*/EP              ;HOLD IF NO EP
     + /LOAD*/Q1*/Q0              ;HOLD IF Q1,Q0=L
     + /LOAD* EP* Q1* Q0          ;COUNT IF EP AND Q1,Q0=H

/Q2 :=  CLEAR                     ;CLEAR Q2
     +  LOAD*/D2                  ;LOAD D2
     + /LOAD*/Q2*/EP              ;HOLD IF NO EP
     + /LOAD*/Q2*/Q0              ;HOLD IF Q2,Q0=L
     + /LOAD*/Q2*/Q1              ;HOLD IF Q2,Q1=L
     + /LOAD* EP* Q2* Q1* Q0      ;COUNT IF EP AND Q2,Q1,Q0=H

/Q3 :=  CLEAR                     ;CLEAR Q3 (MSB)
     +  LOAD*/D3                  ;LOAD D3
     + /LOAD*/Q3*/EP              ;HOLD IF NO EP
     + /LOAD*/Q3*/Q0              ;HOLD IF Q3,Q0=L
     + /LOAD*/Q3*/Q1              ;HOLD IF Q3,Q1=L
     + /LOAD*/Q3*/Q2              ;HOLD IF Q3,Q2=L
     + /LOAD* EP* Q3* Q2* Q1* Q0  ;COUNT IF EP AND Q3,Q2,Q1,Q0=H

 EP :=   CLEAR                    ;INITIALIZE REGISTER
     +  /Q3 + /Q2 + /Q1           ;HOLD IF Q3,Q2,Q1=H


FUNCTION TABLE

CLK /OC CLEAR /LOAD /EP D3 D2 D1 D0 Q3 Q2 Q1 Q0

;CONTROL   ---OPERATION---   DDDD   QQQQ      COMMENTS
;CLK /OC   CLEAR /LOAD /EP   3210   3210    (HEX VALUES)
-------------------------------------------------------------------
  C   L      H     H    L    XXXX   LLLL    CLEAR (0)
  C   L      L     H    L    XXXX   LLLH    COUNT (1)
  C   L      L     H    L    XXXX   LLHL    COUNT (2)
  C   L      L     H    L    XXXX   LLHH    COUNT (3)
  C   L      L     H    L    XXXX   LHLL    COUNT (4)
  C   L      L     H    L    XXXX   LHLH    COUNT (5)
  C   L      L     H    L    XXXX   LHHL    COUNT (6)
  C   L      L     H    L    XXXX   LHHH    COUNT (7)
  C   L      L     H    L    XXXX   HLLL    COUNT (8)
  C   L      L     H    L    XXXX   HLLH    COUNT (9)
  C   L      L     H    L    XXXX   HLHL    COUNT (A)
  C   L      L     H    L    XXXX   HLHH    COUNT (B)
  C   L      L     H    L    XXXX   HHLL    COUNT (C)
  C   L      L     H    L    XXXX   HHLH    COUNT (D)
  C   L      L     H    L    XXXX   HHHL    COUNT (E)
  C   L      L     H    H    XXXX   HHHH    COUNT (F)
  C   L      L     H    H    XXXX   HHHH    HOLD AT TERMINAL COUNT
  C   L      L     L    X    LLLL   LLLL    LOAD (0)
  C   L      L     L    X    LLLH   LLLH    LOAD (1)
  C   L      L     L    X    LLHL   LLHL    LOAD (3)
  C   L      L     L    X    LHLL   LHLL    LOAD (4)
  C   L      L     L    X    HLLL   HLLL    LOAD (8)
  C   L      L     L    X    HHLL   HHLL    LOAD (C)
  C   L      L     L    X    HHHL   HHHL    LOAD (E)
  C   L      L     L    X    HHHH   HHHH    LOAD (F)
  X   H      X     X    Z    XXXX   ZZZZ    TEST HI-Z
-------------------------------------------------------------------


DESCRIPTION

THE 4-BIT COUNTER LOADS DATA, INCREMENTS, OR HOLDS ON THE RISING EDGE
OF THE CLOCK (CLK).

THE COUNTER WILL HOLD WHEN THE TERMINAL COUNT IS REACHED UNTIL NEW DATA
IS LOADED OR THE REGISTERS ARE CLEARED.

THESE OPERATIONS ARE EXERCISED IN THE FUNCTION TABLE AND SUMMARIZED IN THE
IN THE OPERATIONS TABLE:

    /OC  CLK  CLEAR  /LOAD  /EP  D3-D0  Q3-Q0    OPERATION
   --------------------------------------------------------
     H    X     X      X     X     X      Z      HI-Z
     L    C     H      X     X     L      L      CLEAR
     L    C     L      L     X     A      A      LOAD
     L    C     L      H     H     X      Q      HOLD
     L    C     L      H     L     X   Q PLUS 1  INCREMENT
   --------------------------------------------------------