箭10.10

    ; source     module 1
    ;***************************************************
     global     segment public
     extrn      var1:word,var2:word
     global     ends
    ;***************************************************
     local_data   segment
     .
     .
     .
     local_data   ends
    ;***************************************************
     code      segment
         assume cs:code,ds:local_data,es:global
    ;---------------------------------------------------
     main      proc far
  start:
     mov       ax,local_data
     mov       ds,ax
     mov       ax,global
     mov       es,ax
     .
     .
     .
     mov       bx,es:var1
     add       es:var2,bx
     .
     .
     .
     mov       ax,4c00h
     int       21h
     main      endp
    ;----------------------------------------------------
     code      ends
    ;***************************************************
     end       start

    ; source     module 2
    ;**************************************************
     global     segment public
     public     var1,var2
     var1      dw ?
     var2      dw ?
     .
     .
     .
     global     ends
    ;**************************************************
     .
     .
     .
    ;**************************************************
     end