Код
Buff[0] = ((unsigned char[])&A)[0];
Buff[1] = ((unsigned char[])&A)[1];
Buff[2] = ((unsigned char[])&A)[2];
Buff[3] = ((unsigned char[])&A)[3];
Итог
Код
MOV Buff,A
MOV Buff+01H,A+01H
MOV Buff+02H,A+02H
MOV Buff+03H,A+03H
Хотя способов сделать требуемое много.