Uncategorized

80386DX AND 80486 (32-BIT) MEMORY INTERFACE As with 8- and 16-bit memory systems, the microprocessor interfaces to memory through its data bus and control signals that select separate memory banks. The only difference with a 32-bit memory system is that the microprocessor has a 32-bit data bus and four banks of memory, instead of one […]
Continue reading…

8086, 80186, 80286, AND 80386SX (16-BIT) MEMORY INTERFACE The 8086, 80186, 80286, and 80386SX microprocessors differ from the 8088/80188 in three ways: (1) The data bus is 16 bits wide instead of 8 bits wide as on the 8088; (2) the IO>M pin of the 8088 is replaced with an M> IO pin; and (3) […]
Continue reading…

8088 AND 80188 (8-BIT) MEMORY INTERFACE This text contains separate sections on memory interfacing for the 8088 and 80188 with their 8-bit data buses; the 8086, 80186, 80286, and 80386SX with their 16-bit data buses; the 80386DX and 80486 with their 32-bit data buses; the Pentium–Core2 with their 64-bit data buses. Separate sections are provided […]
Continue reading…

ADDRESS DECODING In order to attach a memory device to the microprocessor, it is necessary to decode the address sent from the microprocessor. Decoding makes the memory function at a unique section or partition of the memory map. Without an address decoder, only one memory device can be connected to a microprocessor, which would make […]
Continue reading…

Memory Interface INTRODUCTION Whether simple or complex, every microprocessor-based system has a memory system. The Intel family of microprocessors is no different from any other in this respect. Almost all systems contain two main types of memory: read-only memory (ROM) and random access memory (RAM) or read/write memory. Read-only memory contains system software and permanent […]
Continue reading…

QUESTIONS AND PROBLEMS 1. List the differences between the 8086 and the 8088 microprocessors. 2. Is the 8086/8088 TTL-compatible? Explain your answer. 3. What is the fan-out from the 8086/8088 to the following devices: (a) 74XXX TTL (b) 74ALSXXX TTL (c) 74HCXXX CMOS 4. What information appears on the address/data bus of the 8088 while […]
Continue reading…

SUMMARY 1. The main differences between the 8086 and 8088 are (1) an 8-bit data bus on the 8088 and a 16-bit data bus on the 8086, (2) an SS0 pin on the 8088 in place of BHE /S7 on the 8086, and (3) an IO/M pin on the 8088 instead of an M/ IO […]
Continue reading…

MINIMUM MODE VERSUS MAXIMUM MODE There are two available modes of operation for the 8086/8088 microprocessors: minimum mode and maximum mode. Minimum mode operation is obtained by connecting the mode selection pin MN>MX to +5.0 V, and maximum mode is selected by grounding this pin. Both modes enable different control structures for the 8086/8088 microprocessors. […]
Continue reading…

READY AND THE WAIT STATE As we mentioned earlier in this chapter, the READY input causes wait states for slower memory and I/O components. A wait state (Tw) is an extra clocking period, inserted between T2 and T3 to lengthen the bus cycle. If one wait state is inserted, then the memory access time, normally […]
Continue reading…

BUS TIMING It is essential to understand system bus timing before choosing a memory or I/O device for inter- facing to the 8086 or 8088 microprocessors. This section provides insight into the operation of the bus signals and the basic read and write timing of the 8086/8088. It is important to note that we discuss […]
Continue reading…