.data             ;data segment

TestValue_00 byte 0       ;an 8-bit variable
TestValue_01 word 0       ;a 16-bit variable
TestValue_02 dword 0      ;a 32-bit variable

.code

start:

mov dh, byte ptr [ds:TestValue_00]     ;load the value stored at the address "TestValue_00"
mov ax, word ptr [ds:TestValue_01]     ;load the value stored at the address "TestValue_01"