pep9课下作业

(1)编写一个伪代码算法，读入三个值，输出它们的和。

    Set sum to 0
    Set counter to 0
    Set limit to number of values to sum
    WHILE(counter<limit)
    Read num
    Set sum to sum + num
    Set counter to counter + 1
    Write sum

（2）用PEP/9 机器指令实现（1）中的算法，提交测试结果截图。

（3）用PEP/9 汇编语言实现（1）中的算法，提交测试结果截图。

    BR      main        
sum:      .WORD   0x0000
num:      .BLOCK  2
limit:    .BLOCK  2
counter:  .WORD   0x0000

main:     DECI    limit,d

loop:     DECI    num,d
          LDWA    num,d
          ADDA    sum,d
          STWA    sum,d
          LDWA    counter,d
          ADDA    1,i
          STWA    counter.d
          CPWA    limit,d
          BREQ    finish
          BR      loop;

finish:   DECO    sum,d
          STOP
          .END