PAL16X4                                              PAL DESIGN SPECIFICATION
P7026                                                   BIRKNER/COLI 10/31/81
4-BIT UP/DOWN COUNTER WITH SHIFT REGISTER AND COMPARATOR
MMI SUNNYVALE, CALIFORNIA
CLK  I0   I1 B0 B1 B2 B3  I2  CLR GND
/OC /LIO /GE A3 A2 A1 A0 /LE /RIO VCC


IF (/I2* I1*/I0) RIO = (A0)                              ;SHIFT RIGHT OUT

/A0 :=  /I2*/I1*/I0*(/A0)*/CLR                           ;HOLD A0
     +  /I2*/I1* I0*(/B0)*/CLR                           ;LOAD B0 (LSB)
     +  /I2* I1*/I0*(/A1)*/CLR                           ;SHIFT RIGHT
     +   I2* I1*    (/A0)*/CLR                           ;HOLD (INC AND DEC)
    :+:  I2*/I1*/I0*/RIO                                 ;SHIFT LEFT
     +   I2* I1*/I0* RIO                                 ;INCREMENT IF CARRY IN
     +   I2* I1* I0* RIO                                 ;DECREMENT IF BORROW IN     +   CLR                                             ;CLEAR LSB

/A1 :=  /I2*/I1*/I0*(/A1)*/CLR                           ;HOLD A1
     +  /I2*/I1* I0*(/B1)*/CLR                           ;LOAD B1
     +  /I2* I1*/I0*(/A2)*/CLR                           ;SHIFT RIGHT
     +   I2* I1*    (/A1)*/CLR                           ;HOLD (INC AND DEC)
    :+:  I2*/I1*/I0*(/A0)                                ;SHIFT LEFT
     +   I2* I1*/I0*( A0)* RIO                           ;INCREMENT IF CARRY IN
     +   I2* I1* I0*(/A0)* RIO                           ;DECREMENT IF BORROW IN     +   CLR