1. Lecture 12 8086/8088 Hardware Specifications and Memory Interface Presented By Dr. Shazzad Hosain Asst. Prof. EECS, NSU

2. 8086 Microprocessor8088 Microprocessor 8.1: Barry B. Brey

3. Chapter 9: Memory Interface 1K Memory has A 0 – A 9 4K Memory has A 0 – A 11 Address Pins O 0 – O 7 for 8 bit computer O 0 – O 15 for 16 bit computer Output/Data Pins

4. 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

5. NAND Gate Decoder Decode memory address locations FF800H – FFFFFH 1111 1111 1000 0000 0000 = FF800H 1111 1111 1111 1111 1111 = FFFFFH Figure: 9-12

6. Develop a NAND gate decoder so that it decodes the memory range DF800H – DFFFFH More Example

7. The 3-to-8 Line Decoder (74LS138)

8. 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 ****

9. 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 ****

10. A 13 A 14 A 15 A 16 A 17 A 18 A 19

11. References Chapter 8, 9 The Intel Microprocessors – by Barry B. Brey