PAL14L4 PAL DESIGN SPECIFICATION P7058 VINCENT COLI 10/05/81 4-BIT SHIFTER MMI SUNNYVALE, CALIFORNIA D-3 D-2 D-1 D0 D1 D2 D3 NC NC GND S I0 I1 Y3 Y2 Y1 Y0 NC NC VCC /Y0 = /S*/I1*/I0*/D0 ;NO SHIFT (D0) + /S*/I1* I0*/D-1 ;SHIFT 1 PLACE (D-1) + /S* I1*/I0*/D-2 ;SHIFT 2 PLACES (D-2) + /S* I1* I0*/D-3 ;SHIFT 3 PLACES (D-3) /Y1 = /S*/I1*/I0*/D1 ;NO SHIFT (D1) + /S*/I1* I0*/D0 ;SHIFT 1 PLACE (D0) + /S* I1*/I0*/D-1 ;SHIFT 2 PLACES (D-1) + /S* I1* I0*/D-2 ;SHIFT 3 PLACES (D-2) /Y2 = /S*/I1*/I0*/D2 ;NO SHIFT (D2) + /S*/I1* I0*/D1 ;SHIFT 1 PLACE (D1) + /S* I1*/I0*/D0 ;SHIFT 2 PLACES (D0) + /S* I1* I0*/D-1 ;SHIFT 3 PLACES (D-1) /Y3 = /S*/I1*/I0*/D3 ;NO SHIFT (D3) + /S*/I1* I0*/D2 ;SHIFT 1 PLACE (D2) + /S* I1*/I0*/D1 ;SHIFT 2 PLACES (D1) + /S* I1* I0*/D0 ;SHIFT 3 PLACES (D0) FUNCTION TABLE S I1 I0 D3 D2 D1 D0 D-1 D-2 D-3 Y3 Y2 Y1 Y0 ;CONTROL INPUTS OUTPUTS ; I I DDDD D- YYYY ; S 1 0 3210 123 3210 COMMENTS ------------------------------------------------------------ L L L HHHL HHH HHHL NO SHIFT L (I=0) L L H HHHL HHH HHLH SHIFT L 1 PLACE (I=1) L H L HHHL HHH HLHH SHIFT L 2 PLACES (I=2) L H H HHHL HHH LHHH SHIFT L 3 PLACES (I=3) L L L LLLH LLL LLLH NO SHIFT H (I=0) L L H LLLH LLL LLHL SHIFT H 1 PLACE (I=1) L H L LLLH LLL LHLL SHIFT H 2 PLACES (I=2) L H H LLLH LLL HLLL SHIFT H 3 PLACES (I=3) L L L LLLL HHH LLLL NO SHIFT L's (I=0) L L H HLLL LHH LLLL SHIFT L's 1 PLACE (I=1) L H L HHLL LLH LLLL SHIFT L's 2 PLACES (I=2) L H H HHHL LLL LLLL SHIFT L's 3 PLACES (I=3) L L L HHHH LLL HHHH NO SHIFT H's (I=0) L L H LHHH HLL HHHH SHIFT H's 1 PLACE (I=1) L H L LLHH HHL HHHH SHIFT H's 2 PLACES (I=2) L H H LLLH HHH HHHH SHIFT H's 3 PLACES (I=3) H X X LLLL LLL HHHH STROBE TEST WITH S=L H X X HHHH HHH HHHH STROBE TEST WITH S=H ------------------------------------------------------------ DESCRIPTION THE 4-BIT SHIFTER ACCEPTS A 4-BIT DATA WORD (D) AND SHIFTS THE WORD 0, 1, 2, OR 3 PLACES TO OUTPUTS (Y). THE NUMBER OF PLACES TO BE SHIFTED IS DETERMINED BY TWO CONTROL LINES (I1,I0) WHICH ARE ENCODED IN BINARY WITH I0 REPRESENTING THE LSB. A STROBE LINE (S) IS PROVIDED TO GATE THE OUTPUTS OFF (Y=H) WHEN THE STROBE INPUT IS HIGH. OPERATIONS TABLE: S I1 I0 D3-D-3 Y3-Y0 OPERATION -------------------------------------------- H X X X H STROBE HIGH L L L D D NO SHIFT L L H D S(D)1 SHIFT 1 PLACE L H L D S(D)2 SHIFT 2 PLACES L H H D S(D)3 SHIFT 3 PLACES -------------------------------------------- TWO OR MORE 4-BIT SHIFTERS MAY BE CONNECTED TO IMPLEMENT LARGER SHIFTERS. SHIFTING CAN BE LOGICAL, WITH ZEROES PULLED IN AT EITHER OR BOTH ENDS OF THE SHIFTING FIELD; ARITHMETIC, WHERE THE SIGN BIT IS REPEATED DURING A SHIFT DOWN; OR END AROUND, WHERE THE DATA WORD FORMS A CONTINUOUS LOOP.