▁uses ▁a ▁ 3 6 - bit ▁segment ed ▁virtual ▁address ▁space . ▁ ▁We ’ ll ▁look ▁later ▁at ▁the ▁address ing ▁architecture . ▁ ▁The ▁ 2 2 0 0 ▁Series ▁is ▁a ▁C IS C ▁architecture ▁system . ▁ ▁Not ▁only ▁are ▁there ▁a ▁large ▁number ▁of ▁instructions ▁( current ▁count ▁is ▁about ▁ 2 4 5 ) ▁but ▁many ▁of ▁them ▁have ▁address ing ▁variants . ▁ ▁Some ▁of ▁the ▁variants ▁are ▁encoded ▁directly ▁in ▁the ▁instruction ▁format ▁( partial ▁word ▁references ) ▁and ▁some ▁are ▁dependent ▁on ▁Process or ▁State ▁Register ▁settings . ▁ ▁Many ▁instructions ▁also ▁perform ▁very ▁complex ▁functions ▁such ▁as ▁one ▁that ▁implements ▁a ▁large ▁part ▁of ▁the ▁CO B OL ▁EDIT ▁verb . ▁ ▁The ▁above ▁figure ▁shows ▁some ▁of ▁the ▁building ▁blocks ▁of ▁the ▁architecture . ▁ ▁" Data " ▁and ▁" CO MM " ▁are ▁two ▁of ▁the ▁primary ▁examples ▁of ▁software ▁sub system s ▁that ▁live ▁in ▁a ▁protection ▁ring ▁between ▁that ▁of ▁a ▁user ▁application ▁and ▁the ▁Exec . ▁ ▁There ▁are ▁many ▁other ▁such ▁sub system s ▁and ▁users ▁write ▁their ▁own . ▁ ▁Memory ▁and ▁Address ing ▁ ▁Level ▁▁ ▁As ▁was ▁mentioned ▁earlier ▁the ▁ 2 2 0 0 ▁Series ▁uses ▁a ▁ 3 6 - bit ▁segment ed ▁virtual ▁address . ▁ ▁The ▁original ▁notion ▁of ▁a ▁segment ed ▁space ▁came ▁from ▁the ▁earliest ▁implementation ▁that ▁emphas ized ▁code ▁and ▁data ▁separation ▁for ▁performance ▁and ▁the ▁use ▁of ▁shared ▁code ▁banks . ▁ ▁Over ▁the ▁years