Connecting Intel 386EX to External Device

From: Ravi kumar.N (ravikumar.n_at_sunlux-india.com)
Date: 08/30/04 

Date: 30 Aug 2004 00:11:52 -0700

Respected Experts,
                 In the given figure assume one box as Intel 386EX
embedded processor and the other one as external device(eg: memory).

               Intel 386EX processor External decice(eg:memory)
                .------------. .-------------.
                . . . .
                . W/r#. . .
                . . . .
                . rd# .------------ .rd# .
                . wr# .------------ .wr# .
                . . . .
                .------------. .-------------.
               
  
  The rd# of processor is connected to rd# of external device.
  The wr# of processor is connected to wr# of external device.

 Intel has provided 3 pins on chip .i.e. w/r#, rd#, wr# for
controlling of read and write cycle.

 1) what is the purpose of providing 2 sets of control signals.i.e.
w/r# and rd#, wr#.

2) Is there any significance of w/r#.

3) Which is the better way of connecting 386EX to external device.

4) who controls these 3 pins. Is it possible to control these pins by
the user.

5) what happens if w/r# is left floating.
  
6) We suspect some timing problem in read and write cycle, so is it
necessary to make rd# and wr# as a function of w/r# to avoid timing
problems.

 With regards
 Ravi Kumar.N

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