Logic Circuit

• Inputs to the Logic Circuit

  • address lines A15 - A2(the I/0 address space is 216 addresses, and A1 and A0 are used for the chip’s address lines)
  • the 8088’s IO/M lineHIGH denotes an IO instruction (IN, OUT)LOW denotes a memory access instruction (i.e., MOV)

• Output of the logic circuit

  • a single low value from the 15 inputs (a NAND or OR gate) to activate the Chip Select

• The connections for A15-A2 fix the chip’s address in I/O space

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