Pep/9课下作业

（1）编写伪代码算法，读入三个值，输入它们的和。

 Set sum to 0
 Read num1
 Set sum to sum + num1
 Read num2
 Set sum to sum + num2
 Read num3
 Set sum to sum + num3
 Write sum

(2)机器指令

 12 00 0B 00 00 00 00 00 00 00 00 C1 00 03 31 00
 05 61 00 05 31 00 07 61 00 07 31 00 09 61 00 09
 E1 00 03 39 00 03 00 zz

（3)汇编语言

               BR      main
     sum:     .WORD   0x0000
     num1:    .BLOCK  2
     num2:    .BLOCK  2           
     num3:    .BLOCK  2

     main:    LDWA    sum,d
              DECI    num1,d
              ADDA    num1,d
              DECI    num2,d
              ADDA    num2,d
              DECI    num3,d
              ADDA    num3,d
              STWA    sum,d
              DECO    sum,d
              STOP
              .END