文档介绍：课前****题: 课前****题: ??1 1、已知: 、已知: 18 18 10 10 =00010010 =00010010 2 2求其相反数的补码表示: 求其相反数的补码表示: -18 -18 10 10 =( ) =( ) 2 2 ??2 2、写出、写出-49 -49 10 10的二进制原码、补码的二进制原码、补码表示。表示。??3 3、已知: 、已知: 10011101 10011101 2 2是某个数的是某个数的补码,问其用十进制的表达为? 补码,问其用十进制的表达为? ??4 4、分别以符号、分别以符号- -数值数制、反码、数值数制、反码、补码将补码将-39 -39 表示为一个表示为一个 8 8位数。位数。??1 1、已知: 、已知: 18 18 10 10 =00010010 =00010010 2 2求其相反数的补码表示: 求其相反数的补码表示: -18 -18 10 10 =( =( 11101110 11101110 ) ) 2 2 ??2 2、写出、写出-49 -49 10 10的的8 8为二进制原码、为二进制原码、补码表示。补码表示。 10110001,11001111 10110001,11001111 ??3 3、已知: 、已知: 10011101 10011101 2 2是某个数的是某个数的补码,问其用十进制的表达为? 补码,问其用十进制的表达为? -99 -99 ??4 4、分别以符号、分别以符号- -数值数制、反码、数值数制、反码、补码将补码将-24 -24 表示为一个表示为一个 8 8位数。位数。 10011000,11100111,11101000 10011000,11100111,11101000 Sum up for plement Sum up for plement ( ( 总结总结) ) 1. 1. Positive number has the same Positive number has the same : : Sign-Magnitude, Sign-Magnitude, Ones Ones ’’–– Complement, Complement, and Two and Two ’’ s- Complement s- Complement ( ( 正数的原码、反码、补码相同正数的原码、反码、补码相同) ) Sum up for plement Sum up for plement ( ( 总结总结) ) Complement Number Systems signed-magnitude system (010001) (101111) (010001) (1 10001) +17 10 -17 10不变+17 10 -17 10 符号位改变符号位不变其余按位取反加 1. 连同符号位一起按位取反加 1. 连同符号位一起按位取反加 1. 符号位改变 Sign extension Sign extension ( (符号位扩展符号位扩展) ) ?? We can convert an We can convert an n n -bit -bit two two ’’ s s complement number complement number X X into an into an m m -bit -bit one, but some care is needed. one, but some care is needed. ?? If If m m > > n n , we must append , we must append m m - - n n copies copies of of X X’’ s s sign bit sign bit to the left of to the left of X X . That is, . That is, we pad a positive number with 0s and we pad a positive number with 0s and a a negative one with 1s; this is called negative one with 1s; this is called sign exte