PAL20X8 PAL DESIGN SPECIFICATION P7020 (SN54/74LS498) UDI GORDON 02/20/81 OCTAL SHIFT REGISTER MMI SUNNYVALE, CALIFORNIA CLK I0 D0 D1 D2 D3 D4 D5 D6 D7 I1 GND /OC RILO Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0 LIRO VCC /Q0 := /I1*/I0*/Q0 ;HOLD Q0 + /I1* I0*/Q1 ;SHIFT RIGHT :+: I1*/I0*/LIRO ;SHIFT LEFT + I1* I0*/D0 ;LOAD D0 /Q1 := /I1*/I0*/Q1 ;HOLD Q1 + /I1* I0*/Q2 ;SHIFT RIGHT :+: I1*/I0*/Q0 ;SHIFT LEFT + I1* I0*/D1 ;LOAD D1 /Q2 := /I1*/I0*/Q2 ;HOLD Q2 + /I1* I0*/Q3 ;SHIFT RIGHT :+: I1*/I0*/Q1 ;SHIFT LEFT + I1* I0*/D2 ;LOAD D2 /Q3 := /I1*/I0*/Q3 ;HOLD Q3 + /I1* I0*/Q4 ;SHIFT RIGHT :+: I1*/I0*/Q2 ;SHIFT LEFT + I1* I0*/D3 ;LOAD D3 /Q4 := /I1*/I0*/Q4 ;HOLD Q4 + /I1* I0*/Q5 ;SHIFT RIGHT :+: I1*/I0*/Q3 ;SHIFT LEFT + I1* I0*/D4 ;LOAD D4 /Q5 := /I1*/I0*/Q5 ;HOLD Q5 + /I1* I0*/Q6 ;SHIFT RIGHT :+: I1*/I0*/Q4 ;SHIFT LEFT + I1* I0*/D5 ;LOAD D5 /Q6 := /I1*/I0*/Q6 ;HOLD Q6 + /I1* I0*/Q7 ;SHIFT RIGHT :+: I1*/I0*/Q5 ;SHIFT LEFT + I1* I0*/D6 ;LOAD D6 /Q7 := /I1*/I0*/Q7 ;HOLD Q7 + /I1* I0*/RILO ;SHIFT RIGHT :+: I1*/I0*/Q6 ;SHIFT LEFT + I1* I0*/D7 ;LOAD D7 IF(/I1*I0) /LIRO = /Q0 ;LEFT IN RIGHT OUT IF(I1*/I0) /RILO = /Q7 ;RIGHT IN LEFT OUT FUNCTION TABLE I1 I0 D7 D6 D5 D4 D3 D2 D1 D0 CLK /OC RILO LIRO Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0 ; DATA IN Q OUT ;INST D7----D0 CLK /OC RILO LIRO Q7----Q0 COMMENTS ----------------------------------------------------------------------- HH LLLLLLLL C L Z Z LLLLLLLL LOAD ZEROS LL XXXXXXXX C L Z Z LLLLLLLL HOLD HL XXXXXXXX C L L H LLLLLLLH SHIFT LEFT IN A H HL XXXXXXXX C L L L LLLLLLHL SHIFT LEFT IN A L HL XXXXXXXX C L L L LLLLLHLL SHIFT LEFT IN A L HL XXXXXXXX C L L L LLLLHLLL SHIFT LEFT IN A L HL XXXXXXXX C L L L LLLHLLLL SHIFT LEFT IN A L HL XXXXXXXX C L L L LLHLLLLL SHIFT LEFT IN A L HL XXXXXXXX C L L L LHLLLLLL SHIFT LEFT IN A L HL XXXXXXXX C L H L HLLLLLLL SHIFT LEFT IN A L HL XXXXXXXX C L L L LLLLLLLL SHIFT LEFT IN A L LL XXXXXXXX X H Z Z ZZZZZZZZ TEST HI-Z HH HHHHHHHH C L Z Z HHHHHHHH LOAD ONES LL XXXXXXXX C L Z Z HHHHHHHH HOLD LH XXXXXXXX C L L H LHHHHHHH SHIFT RIGHT IN A L LH XXXXXXXX C L H H HLHHHHHH SHIFT RIGHT IN A H LH XXXXXXXX C L H H HHLHHHHH SHIFT RIGHT IN A H LH XXXXXXXX C L H H HHHLHHHH SHIFT RIGHT IN A H LH XXXXXXXX C L H H HHHHLHHH SHIFT RIGHT IN A H LH XXXXXXXX C L H H HHHHHLHH SHIFT RIGHT IN A H LH XXXXXXXX C L H H HHHHHHLH SHIFT RIGHT IN A H LH XXXXXXXX C L H L HHHHHHHL SHIFT RIGHT IN A H LH XXXXXXXX C L H H HHHHHHHH SHIFT RIGHT IN A H LL XXXXXXXX X H Z Z ZZZZZZZZ TEST HI-Z ----------------------------------------------------------------------- DESCRIPTION THIS PAL IS AN 8-BIT SHIFT REGISTER WITH PARALLEL LOAD AND HOLD CAPABILITY. TWO FUNCTION SELECT INPUTS (I0,I1) PROVIDE ONE OF FOUR OPERATIONS WHICH OCCUR SYNCHRONOUSLY ON THE RISING EDGE OF THE CLOCK (CLK). THESE OPERATIONS ARE: /OC CLK I1 I0 D7-D0 Q7-Q0 OPERATION ----------------------------------------------- H X X X X Z HI-Z L C L L X L HOLD L C L H X SR(Q) SHIFT RIGHT L C H L X SL(Q) SHIFT LEFT L C H H D D LOAD ----------------------------------------------- TWO OR MORE OCTAL SHIFT REGISTERS MAY BE CASCADED TO PROVIDE LARGER SHIFT REGISTERS. RILO AND LIRO ARE LOCATED ON PINS 14 AND 23 RESPECTIVELY, WHICH PROVIDES FOR CONVENIENT INTERCONNECTIONS WHEN TWO OR MORE OCTAL SHIFT REGISTERS ARE CASCADED TO IMPLEMENT LARGER SHIFT REGISTERS.