;chapter 4 exercise 4.1 page 65

mov ax, 0FFFFh' = -1; ax = FFFFh

inc ax; = 0000h
move ax, 0ffffh 
inc al; ax = ff00h
mov ax 0ffffh
inc ah; ax= 00ffh
mov ax 1234h
sub ax, 35h; ax= 11ffh

mov ax, 1234h
sub al 35h; ax= 12FFh

mov ax, 1234h
neg ax; ax = EDCCh
mov ax, 1234h
neg al; ax = 12CCh
mov ax, 1234h
mov al, -1; ax = 12ffh

inc ax; ax= 1300h;
mov ax, 12ffh
inc al ; ax =  1200h
mov ax, 1200h
dec ax; ax = 11ffh
mov ax, 1200h
dec al; ax = 12ffh;
mov ax, 1234h
sub ax, ax; ax 0000h;
mov ax 1234h
sub al, al; ax = 1200h;