PAL20X4 PAL DESIGN SPECIFICATION P7060 MIKE VOLPIGNO 11/20/81 4-BIT COUNTER WITH TRANSPARENT LATCH MMI FIELD APPLICATIONS ENGINEER NEWTON, MASSACHUSETTS CLK /CLR /CNT /LD D0 D1 D2 D3 /LEN SEL /LOC GND /OC /CO Y3 Y2 Q3 Q2 Q1 Q0 Y1 Y0 /CI VCC /Q0 := CLR ;CLEAR COUNTER (Q0) + /CLR*/LD*/Q0 ;COUNT/HOLD (LSB) :+: /CLR* LD*/Y0 ;LOAD COUNTER FROM LATCH + /CLR*/LD* CNT* CI ;COUNT /Q1 := CLR ;CLEAR COUNTER (Q1) + /CLR*/LD*/Q1 ;COUNT/HOLD :+: /CLR* LD*/Y1 ;LOAD COUNTER FROM LATCH + /CLR*/LD* CNT* CI* Q0 ;COUNT /Q2 := CLR ;CLEAR COUNTER (Q2) + /CLR*/LD*/Q2 ;COUNT/HOLD :+: /CLR* LD*/Y2 ;LOAD COUNTER FROM LATCH + /CLR*/LD* CNT* CI* Q0* Q1 ;COUNT /Q3 := CLR ;CLEAR COUNTER (Q3) + /CLR*/LD*/Q3 ;COUNT/HOLD (MSB) :+: /CLR* LD*/Y3 ;LOAD COUNTER FROM LATCH + /CLR*/LD* CNT* CI* Q0* Q1* Q2 ;COUNT IF(VCC) CO = CNT* CI* Q0* Q1* Q2* Q3 ;CARRY OUT IF(LOC) /Y0 = LEN*/D0*/SEL ;SELECT DATA (D0) + LEN*/Q0* SEL ;SELECT COUNTER (Q0) + /LEN*/Y0 ;LATCH OUTPUT (Y0) IF(LOC) /Y1 = LEN*/D1*/SEL ;SELECT DATA (D1) + LEN*/Q1* SEL ;SELECT COUNTER (Q1) + /LEN*/Y1 ;LATCH OUTPUT (Y1) IF(LOC) /Y2 = LEN*/D2*/SEL ;SELECT DATA (D2) + LEN*/Q2* SEL ;SELECT COUNTER (Q2) + /LEN*/Y2 ;LATCH OUTPUT (Y2) IF(LOC) /Y3 = LEN*/D3*/SEL ;SELECT DATA (D3) + LEN*/Q3* SEL ;SELECT COUNTER (Q3) + /LEN*/Y3 ;LATCH OUTPUT (Y3) FUNCTION TABLE CLK /OC /CLR /LD /CNT /LOC /LEN SEL D3 D2 D1 D0 /CI /CO Q3 Q2 Q1 Q0 Y3 Y2 Y1 Y0 ;C COUNTER CONTROL LATCH CONTROL DATA CARRY COUNT LATCH ;L / / / / / / DDDD / / QQQQ YYYY COMMENTS ;K OC CLR LD CNT LOC LEN SEL 3210 CI CO 3210 3210 (HEX VALUES) ------------------------------------------------------------------------------- ;TEST COUNTER X X X X X L L L HHHH X X XXXX HHHH SELECT DATA (F) X X X X X L H X HHHH X X XXXX HHHH LATCH DATA (F) C L L X X L H X XXXX X X LLLL HHHH CLEAR COUNTER C L H H L L H X XXXX L H LLLH HHHH INCREMENT (1) C L H H L L H X XXXX L H LLHL HHHH INCREMENT (2) C L H H L L H X XXXX L H LLHH HHHH INCREMENT (3) C L H H L L H X XXXX L H LHLL HHHH INCREMENT (4) C L H H L L H X XXXX L H LHLH HHHH INCREMENT (5) C L H H H L L H XXXX L H LHLH LHLH SELECT COUNTER C L H H H L H X XXXX L H LHLH LHLH LATCH COUNTER C L H H L L H X XXXX L H LHHL LHLH INCREMENT (6) C L H H L L H X XXXX L H LHHH LHLH INCREMENT (7) C L H H L L H X XXXX L H HLLL LHLH INCREMENT (8) C L H H L L H X XXXX L H HLLH LHLH INCREMENT (9) C L H H L L H X XXXX L H HLHL LHLH INCREMENT (A) C L H H L L H X XXXX L H HLHH LHLH INCREMENT (B) C L H H L L H X XXXX L H HHLL LHLH INCREMENT (C) C L H H L L H X XXXX L H HHLH LHLH INCREMENT (D) C L H H L L H X XXXX L H HHHL LHLH INCREMENT (E) C L H H L L H X LLLL L L HHHH LHLH INCREMENT (F) C L H H L L H X HHHH L H LLLL LHLH INCREMENT (0) C L H L X L H X XXXX X X LHLH LHLH LOAD Q FROM Y C L H H H L H X XXXX X H LHLH LHLH HOLD (/CNT=H) C L H L X L L L HLHL X X HLHL HLHL LOAD Q FROM D C L H H L L H X XXXX H H HLHL HLHL HOLD (/CI=H) ;TEST LATCH X X X X X L L L LHHH X X XXXX LHHH SELECT DATA (7) X X X X X L H X HHHL X X XXXX LHHH LATCH DATA (7) X X X X X L L L HLHH X X XXXX HLHH SELECT DATA (B) X X X X X L H X LHLL X X XXXX HLHH LATCH DATA (A) X X X X X L L L HHLH X X XXXX HHLH SELECT DATA (C) X X X X X L H X LLHL X X XXXX HHLH LATCH DATA (C) X X X X X L L L HHHL X X XXXX HHHL SELECT DATA (D) X X X X X L H X LLLH X X XXXX HHHL LATCH DATA (D) ;TEST HI-Z X H X X X X X X XXXX X X ZZZZ XXXX TEST HI-Z COUNT X X X X X H X X XXXX X X XXXX ZZZZ TEST HI-Z LATCH ------------------------------------------------------------------------------- DESCRIPTION THIS PAL DESIGN SPECIFICATION DESCRIBES A 4-BIT COUNTER WITH A 4-BIT TRANS- PARENT LATCH. THE LATCH OUTPUTS (Y3-Y0) WILL FOLLOW EITHER THE DATA INPUTS (D3-D0) OR THE COUNTER STATES (Q3-Q0), DEPENDING ON THE SELECT LINE (SEL), PROVIDING THE LATCH ENABLE IS TRUE (/LEN=L). THE OUTPUTS WILL BE LATCHED AT THE LEVEL OF THE INPUTS WHICH WERE SELECTED WHEN THE LATCH ENABLE IS FALSE (/LEN=H). THE COUNTER IS FULLY SYNCHRONOUS WITH THE RISING EDGE OF THE CLOCK (CLK) AND CAN BE SYNCHRONOUSLY LOADED FROM THE LATCH OUTPUTS. A SYNCHRONOUS OVERRIDING CLEAR (/CLR) IS ALSO PROVIDED. OPERATIONS TABLE: -COUNTER CONTROL- --LATCH CONTROL-- DATA CNTR LATCH CLK /OC /CLR /LD /CNT /LOC /LEN SEL /CI D3-D0 Q3-Q0 Y3-Y0 OPERATION ------------------------------------------------------------------------------- X H X X X X X X X X Z X HI-Z (COUNTER) C L L X X X X X X X L X CLEAR C L H L X L H X X X Y Y LOAD FROM LATCH C L H L X L L L X D D D LOAD FROM DATA C L H H H X X X X X Q X HOLD C L H H L X X X L X Q PLUS 1 X INCREMENT C L H H L X X X H X Q X HOLD X X X X X H X X X X X Z HI-Z (LATCH) X X X X X L H X X X X Y LATCH OUTPUT X X X X X L L L X D X D SELECT DATA X X X X X L L H X X Q Q SELECT COUNTER -------------------------------------------------------------------------------