Intel 81342 Developer's Manual page 903

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U A R T s — I n t e l 8 1 3 4 1 a n d 8 1 3 4 2
T a b l e 5 7 3 . U A R T x M o d e m S t a t u s R e g i s t e r
T h i s r e g i s t e r p r o v i d e s t h e c u r r e n t s t a t e o f t h e c o n t r o l l i n e s f r o m t h e m o d e m o r d a t a s e t
( o r a p e r i p h e r a l d e v i c e e m u l a t i n g a m o d e m ) . I n a d d i t i o n t o t h i s c u r r e n t s t a t e
i n f o r m a t i o n , t h e M o d e m S t a t u s r e g i s t e r a l s o p r o v i d e s c h a n g e i n f o r m a t i o n . T h e c h a n g e
b i t i s s e t t o a l o g i c 1 w h e n t h e c o n t r o l i n p u t f r o m t h e M o d e m c h a n g e s s t a t e . T h e c h a n g e
b i t i s r e s e t t o a l o g i c 0 w h e n t h e p r o c e s s o r r e a d s t h e M o d e m S t a t u s r e g i s t e r .
N o t e : W h e n t h e c h a n g e b i t ( b i t 0 ) i s s e t t o l o g i c 1 , a M o d e m S t a t u s i n t e r r u p t i s g e n e r a t e d
w h e n b i t 3 o f t h e I n t e r r u p t E n a b l e R e g i s t e r i s s e t .
T a b l e 5 7 4 . U A R T x M o d e m S t a t u s R e g i s t e r - ( U x M S R )
s
3 1
t e
P
b u
r v
I O r i
t t
A
s
t e
I
b u
P C
n a
r i
t t
A
U n i t #
0
1
B i t
31:5
4
3:1
0
D e c e m b e r 2 0 0 7
O r d e r N u m b e r : 3 1 5 0 3 7 - 0 0 2 U S
2 8 2 4
r v r v r v r v r v r v r v r v r v r v
n a n a n a n a n a n a n a n a n a n a
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I n t e l X S c a l e C o r e i n t e r n a l b u s a d d r e s s
+ 2 3 1 8 H ( D L A B = x )
+ 2 3 5 8 H ( D L A B = x )
D e f a u l t
000 0000h Reserved
Clear to Send (CTS): This bit is the complement of the Clear to Send (CTS#) input.
This bit is equivalent to bit RTS of the Modem Control register when LOOP in the
MCR is set to 1.
0
2
0 = CTS# pin is 1
1 = CTS# pin is 0
000 Reserved
2
Delta Clear To Send (DCTS):
0
0 = No change in CTS# pin since last read of MSR
2
1 = CTS# pin has changed state
2 0 1 6 1 2
r v r v r v r v r v r v r v r v r v r v
n a n a n a n a n a n a n a n a n a n a
A t t r i b u t e L e g e n d :
R V = R e s e r v e d
P R = P r e s e r v e d
R S = R e a d / S e t
D e s c r i p t i o n
I n t e l
8 4
r v r v r v r v r v r v r o r v r v r v
n a n a n a n a n a n a n a n a n a n a
R W = R e a d / W r i t e
R C = R e a d C l e a r
R O = R e a d O n l y
N A = N o t A c c e s s i b l e
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8 1 3 4 1 a n d 8 1 3 4 2 I / O P r o c e s s o r s
D e v e l o p e r ' s M a n u a l
0
r o
n a
9 0 3