Intel 81342 Developer's Manual page 586

E x a m p l e 1 2 . D D R R e g i s t e r s P r o g r a m m i n g E x a m p l e 4
T h e u s e r w a n t s t o p r o g r a m t h e D D R r e g i s t e r s t o s u p p o r t t w o b a n k s a n d e a c h D D R b a n k
i s 2 5 6 M B y t e s , y i e l d i n g i n a t o t a l m e m o r y o f 5 1 2 G B y t e ( 2 * 2 5 6 M B ) . T h e u s e r w a n t s
t h e D D R m e m o r y s p a c e t o s t a r t a t B E 0 0 0 0 0 0 0 H . T h e 3 2 - b i t m e m o r y r e g i o n i s
1 2 8 M b y t e s ( B a n k 0 i s e n t i r e l y 3 2 - b i t r e g i o n s i n c e h a l f o f t h e b a n k s p a c e i s l o s t ) . T h e
m e m o r y s p a c e s u m m a r y i s :
T h e r e g i s t e r s w o u l d b e p r o g r a m m e d a s f o l l o w s :
B a n k S i z e = 2 5 6 M B , S B S R [ 3 1 : 2 7 ] = 0 0 0 1 0
N u m b e r o f B a n k s = 2 , S B S R [ 2 ] = 0
S 3 2 S R [ 2 9 : 2 0 ] = 0 8 0 H , S 3 2 S R = 0 8 0 0 0 0 0 0 H
S D U B R = 0 0 0 0 0 0 0 B H , S D U B R [ 3 : 0 ] = 1 0 1 1
S D B R = E 0 0 0 0 0 0 0 H , S D B R [ 3 1 : 2 8 ] = 1 1 1 0
S S D B R = N o t A p p l i c a b l e , a s S e c o n d a r y B a n k S i z e i s E m p t y .
S e c o n d a r y B a n k S i z e = E m p t y , S B S R [ 2 1 : 1 6 ] = 0 0 0 0 0 0
I n t h e a b o v e e x a m p l e , a l t h o u g h 3 2 - b i t r e g i o n i s e n a b l e d , t h e e n t i r e D D R m e m o r y s p a c e
N o t e :
i s s t i l l c o n f i g u r e d a s s u p p o r t i n g a 6 4 - b i t w i d e d a t a b u s , t h a t i s S D C R 0 [ 1 ] = 0
E x a m p l e 1 3 . D D R R e g i s t e r s P r o g r a m m i n g E x a m p l e 5
T h e u s e r w a n t s t o p r o g r a m t h e D D R r e g i s t e r s t o s u p p o r t 1 b a n k o f 3 2 - b i t m e m o r y o n l y .
T h e s m a l l e s t D D R 2 s i z e t h a t c a n b e s u p p o r t e d i s 1 2 8 M B y t e s , a s d i c t a t e d b y t h e D D R 2
t e c h n o l o g y . T h e u s e r w a n t s t h e D D R m e m o r y s p a c e t o s t a r t a t B F 8 0 0 0 0 0 0 H . T h e
m e m o r y s p a c e s u m m a r y i s :
T h e r e g i s t e r s w o u l d b e p r o g r a m m e d a s f o l l o w s :
B a n k S i z e = 1 2 8 M B , S B S R [ 3 1 : 2 7 ] = 0 0 0 0 1
N u m b e r o f B a n k s = 1 , S B S R [ 2 ] = 1
S 3 2 S R [ 2 9 : 2 0 ] = 0 0 0 H , S 3 2 S R = 0 0 0 0 0 0 0 0 H
S D C R 0 [ 1 ] = 1
S D U B R = 0 0 0 0 0 0 0 B H , S D U B R [ 3 : 0 ] = 1 0 1 1
S D B R = F 8 0 0 0 0 0 0 H , S D B R [ 3 1 : 2 7 ] = 1 1 1 1 1
S S D B R = N o t A p p l i c a b l e , a s S e c o n d a r y B a n k S i z e i s E m p t y .
S e c o n d a r y B a n k S i z e = E m p t y , S B S R [ 2 1 : 1 6 ] = 0 0 0 0 0 0
E x a m p l e 1 4 . A d d r e s s R e g i s t e r P r o g r a m m i n g E x a m p l e 6
T h e u s e r w a n t s t o p r o g r a m t h e D D R r e g i s t e r s t o s u p p o r t t w o b a n k s a n d e a c h D D R b a n k
i s 5 1 2 M B y t e s , y i e l d i n g i n a t o t a l m e m o r y o f 1 G B y t e s ( 2 * 5 1 2 M B ) . T h e u s e r w a n t s t h e
D D R m e m o r y s p a c e t o s t a r t a t A C 0 0 0 0 0 0 0 H . T h e u s e r w a n t s a 2 5 6 - M B y t e s e c o n d a r y
w i n d o w s t a r t i n g a t 0 C 0 0 0 0 0 0 H . N o t e t h a t t h e s e c o n d a r y m e m o r y w i n d o w o v e r l a p s t h e
p r i m a r y m e m o r y w i n d o w a n d s t a r t s a t t h e b o t t o m o f t h e p r i m a r y m e m o r y w i n d o w i n
t h i s e x a m p l e . T h e r e a r e n o 3 2 - b i t m e m o r y r e g i o n . T h e m e m o r y s p a c e s u m m a r y i s :
T h e r e g i s t e r s w o u l d b e p r o g r a m m e d a s f o l l o w s :
B a n k S i z e = 5 1 2 M B , S B S R [ 3 1 : 2 7 ] = 0 0 1 0 0
N u m b e r o f B a n k s = 2 , S B S R [ 2 ] = 0
S 3 2 S R [ 2 9 : 2 0 ] = 0 H , S 3 2 S R = 0 0 0 0 0 0 0 0 H
S D U B R = 0 0 0 0 0 0 0 A H , S D U B R [ 3 : 0 ] = 1 0 1 0
S D B R = C 0 0 0 0 0 0 0 H , S D B R [ 3 1 : 2 8 ] = 1 1 0 0
S S D B R = C 0 0 0 0 0 0 0 H
S e c o n d a r y B a n k S i z e = 2 5 6 M B , S B S R [ 2 1 : 1 6 ] = 0 0 0 1 0 0
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