XR88C681CP Datasheet, PDF (46/99 Pages) Exar Corporation – CMOS DUAL CHANNEL UART (DUART)

XR88C681
-"   6 '%   6" /.1  ./
'% 1  / %' $ - + (!$ ( % (%
' $ &   7.5 (  (  B   (% ( (% (- "
  C( D $ (% %'$  $ ( % <  - 1 3 
  '  $+( (( % %   $   7.5 J 
' ( Table 14 B    ==/• , % (  (%
$" ( % %  '  % & %((    +  
==6• ,"  $ E(%  &  $$%% '  $  ''3
-   + 
, $
Pin Number
<
6
/
>
=

1
1
MN/MX = 1 (Min Mode)
89
89
B
.#
.
27
92
#7
MN/MX = 0 (Max Mode)
).0
).0
9
:



)
)
Table 14. MN/MX Mode and Function of Pins 24-31 of 8086 CPU Device.
B  7.5 (% "   ==/• , (% ( - (   C!D
$  (% $ (% (  $$ +  '!
('( % (  ('   ==/• , E(% % +
  ==> (' $ '%% 7, #  (% $" 
%'( % '    === (% E($  - 
  &  $ #. '  % %(- %
  ==/• , ' ( %  (  E% ( %4 #7
 $ 7# 7# (%   '( (- C  %3D ( 
E% ( L  $ #7 (%   C%3D ( 
E% (  #+   ==/• , (% ( - (   C( D
$"     #7 #  '3 $- ( (%
(  ,( < % Figure 20 8" (+  
==/• , (% ( - (   C!D $"     #7
%(-  %  $($ +   " "  $  ( % (
  === % '  Table 15 % %   '%%
%%  $ === '( % %$    " "  $
 C!D $ %% %(- %
S2
S1
S0
























Processor State
#  '3 $-
$ #. ,
B( #. ,
8

$ ''%%
$ &
B( &
,%%(
8288 Active Output
#7
#

#B

7 




B

7 
Table 15. 8086 Processor State/8288 Bus Controller Active Output as a function of S0, S1 and S2
 
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