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Asked: 2022-03-31T11:07:05+05:30 In:

Elaborate the functioning of following bits of Control Word register of 8255 in IO mode: D0 D1 D2 D3 D4

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Elaborate the functioning of following bits of Control Word register of 8255 in IO mode:

  1. D0
  2. D1
  3. D2
  4. D3
  5. D4
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    2. Bit D0 :
      • To make Port CLower as input port this bit set to 1.
      • To make Port CLower as output port this bit set to 0.

       

      Bit D1:
      • To make Port B as input port this bit set to 1.
      • To make Port B as output port this bit set to 0.

       

      Bit D2:
      • If this bit set to 0, the port B will operate in mode 0.
      • If this bit set to 1, the port B will operate in mode 1.

       

      Bit D3:
      • To make Port CUpper as input port this bit set to 1.
      • To make Port CUpper as output port this bit set to 0.
      Bit D4:
      • To make Port A as input port this bit set to 1.
      • To make Port A as output port this bit set to 0.

       

      Bits D5 and D6 :
      • These two bits mainly used for determining the I/O mode of port A.
      •  for 00, it is m0 mode, for 01, it is m2 mode and 10 or 11, it is m2 mode.
      Bit D7:
      • 1 for IO mode and 0 for BSR mode
      • 5

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