Introduction to Bioinformatics - North South University(1)

							           Lecture 12
8086/8088 Hardware Specifications
     and Memory Interface
            Presented By
         Dr. Shazzad Hosain
        Asst. Prof. EECS, NSU
8086 Microprocessor                        8088 Microprocessor
                      8.1: Barry B. Brey
      Chapter 9: Memory Interface
 Address Pins
• 1K Memory has A0 – A9
• 4K Memory has A0 – A11


  Output/Data Pins
• O0 – O7 for 8 bit computer
• O0 – O15 for 16 bit computer
           Address Decoding
• Why need address decoding?
  – 8086/8088 has 20 address pins
  – But EPROM, the memory device has less space
  – For example, 2716 EPROM is a 2K memory device
          NAND Gate Decoder
• Decode memory address locations FF800H – FFFFFH
         1111   1111   1000   0000   0000   =   FF800H
         1111   1111   1111   1111   1111   =   FFFFFH




                                      Figure: 9-12
                 More Example
• Develop a NAND gate decoder so that it decodes the memory
  range DF800H – DFFFFH
The 3-to-8 Line Decoder (74LS138)
• Develop a 64K memory bank using eight 2764 EPROMs, where
  each 2764 EPROM is a 8K memory device and it address the
  memory locations F0000H – FFFFFH

1111 0000 0000 0000 0000 = F0000H
1111 0001 1111 1111 1111 = F1FFFH
1111   0010   0000   0000   0000   =   F2000H
1111   0011   1111   1111   1111   =   F3FFFH
1111   0100   0000   0000   0000   =   F4000H
1111   0101   1111   1111   1111   =   F5FFFH
1111   0110   0000   0000   0000   =   F6000H
1111   0111   1111   1111   1111   =   F7FFFH
1111   1000   0000   0000   0000   =   F8000H
1111   1001   1111   1111   1111   =   F9FFFH
               *
               *
1111 1110 0000 0000 0000 = FE000H
1111 1111 1111 1111 1111 = FFFFFH
1111 0000 0000 0000 0000 = F0000H
1111 0001 1111 1111 1111 = F1FFFH
1111   0010   0000   0000   0000   =   F2000H
1111   0011   1111   1111   1111   =   F3FFFH
1111   0100   0000   0000   0000   =   F4000H
1111   0101   1111   1111   1111   =   F5FFFH
1111   0110   0000   0000   0000   =   F6000H
1111   0111   1111   1111   1111   =   F7FFFH
1111   1000   0000   0000   0000   =   F8000H
1111   1001   1111   1111   1111   =   F9FFFH
               *
               *
1111 1110 0000 0000 0000 = FE000H
1111 1111 1111 1111 1111 = FFFFFH
      A13
      A14
      A15




A16



A17
A18
A19
                    References
• Chapter 8, 9 The Intel Microprocessors – by Barry B.
  Brey