chapter 8.pdf

Section 8.3 Sequential PLDs 587DO NOT COPYPAL16L8PAL16R4PAL16R6PAL16R81111I1CLKCLKCLK219219219219I2 O1I1 IO1I1 IO1I1 O1318318318318I3 IO2I2 IO2I2 O2I2 O2417417417417DOI4 IO3NOTI3 O3I3COPYO3I3 O3516516516516I5 IO4I4 O4I4 O4I4 O4615615615615I6 IO5I5 O5I5 O5I5 O5714714714714I7 IO6I6 O6I6 O6I6 O6813813813813I8 IO7I7 IO7I7 O7I7 O7912912912912DOI9 O8NOTI8 IO8I8COPYIO8I8 O811111111I10OEOEOEPAL20L8PAL20R4PAL20R6PAL20R81111DOI1NOTCLKCLKCOPYCLK2222I2I1I1I13333I3I2I2I2422422422422I4 O1I3 IO1I3 IO1I3 O15 21521521521I5 IO2I4 IO2I4 O2I4 O2620620620620I6 IO3I5 O3I5 O3I5 O37DO19NOT7197COPY19719I7 IO4I6 O4I6 O4I6 O4818818818818I8 IO5I7 O5I7 O5I7 O5917917917917I9 IO6I8 O6I8 O6I8 O61016101610161016I10 IO7I9 IO7I9 O7I9 O71115111511151115I11 O8I10 IO8I10 IO8I10 O813DO14NOT14COPY14I12I11I11I1114232323I13I12I12I1223131313I14OEOEOEFigure 8-19 Logic symbols for bipolar combinational and sequential PLDs.DO NOT COPYAND-OR array with 20 variables and their complements as possible inputs. PAL20R6Figure 8-19 shows logic symbols for all of the PLDs in the table.PAL20R88.3.2DOSequential GAL DevicesNOT COPYThe GAL16V8 electrically erasable PLD was introduced in Section 5.3.3. Two“architecture-control” fuses are used to select among three basic configurationsof this device. Section 5.3.3 described the 16V8C (“complex”) configuration, 16V8Cshown in Figure 5-27 on page 307, a structure similar to that of a bipolarcombinationalDOPAL device, theNOTPAL16L8. The 16V8S (“simple”)COPYconfiguration 16V8Sprovides a slightly different combinational logic capability (see box onpage 589).The third configuration, called the 16V8R, allows a flip-flop to be provided 16V8Ron any or all of the outputs. Figure 8-20 shows the structure of the device whenCopyright © 1999 by John F. WakerlyCopying Prohibited