data segment data ends stack segment dw 100 dup (? tos label ord stack ends code segment maIn proc ar assume cs: code, ds data ss: stack start mov ax. stack mov SS ax mov sp, offset tos push ds sub ax, ax push ES ax PSP mov ax, data moV ds, ax Cs→ ret main endp code ends end start 77 data segment …… data ends stack segment dw 100 dup (?) tos label word stack ends code segment main proc far assume cs:code, ds:data, ss:stack start: mov ax, stack mov ss, ax mov sp, offset tos push ds sub ax, ax push ax mov ax, data mov ds, ax …… ret main endp code ends end start PSP DS→ ES SS→ CS→