Microprocessor & Interfaces

  ADDRESSING MODES OF 8085 To perform any operation, we have to give the corresponding instructions to the microprocessor. In each instruction, programmer has to specify 3 things: Ø    Operation to be performed. Ø    Address of source of data. Ø    Address of destination of result. The method by which the address of source of data or the address of destination of result is given in the instruction is called Addressing Modes.  The term addressing mode refers to the way in which the operand of the instruction is specified. Intel 8085 uses the following addressing modes: 1.       Direct Addressing Mode 2.       Register Addressing Mode 3.       Register Indirect Addressing Mode 4.       Immediate Addressing Mode 5.       Implicit Addressing Mode or Implied Addressing 1. Direct Addressing Mode:- In this mode, the address of the ...

  Introduction to Microprocessor A microprocessor is a multipurpose, programmable, clock-driven, register-based electronic device that reads binary instructions from a storage device called memory, accepts binary data as input and processes data according to those instructions and provides result as output. Figure:- Traditional block diagram of a computer Figure:- Block diagram of computer with the Microprocessor (MPU) Generation of Microprocessor 1st Generation : This was the period during 1971 to 1972 of microprocessor’s history. In 1971, INTEL created the first microprocessor 4004 that would run at a clock speed of 108 KHz. During this period, the other microprocessors in the market including Rockwell international PPS-4, INTEL-8008 and National semiconductors IMP-16 were in use. But, all these were not TTL compatible processors. 2nd Generation : This was the period during 1973 to 1978 in which very efficient 8-bit microprocessors were implemented like Motorola 6800 and 6801, IN...

Pin Configuration and Function of 8085 Properties:-  • It is an 8-bit microprocessor  • Manufactured with N-MOS technology  • 40 pin IC package  • It has 16-bit address bus and thus has 216 = 64 KB addressing capability.  • Operate with 3 MHz single-phase clock • +5 V single power supply  The logic pin layout and signal groups of the 8085microprocessor are shown in Fig. All the signals are classified into six groups:  • Address bus  • Data bus  • Control & status signals  • Power supply and frequency signals  • Externally initiated signals  • Serial I/O signals Figure: - The 8085 Microprocessor Pin Configuration and Signals The Intel 8085A is a new generation, complete 8 bit parallel central processing unit (CPU). The 8085A uses a multiplexed data bus. The address is split between the 8bit address bus and the 8bit data bus. Figures are at the end of the document.  Pin Description  The following describes the funct...

Architecture of 8085 Microprocessor The block diagram explaining the architecture of Intel 8085 Microprocessor is shown in Fig.2.2. It is available generally as a 40 pin IC package and uses +5V for power. It can run at a maximum frequency of 3 MHz The modified versions of the 8085 processor have these minimum common features and functional similarities. 8085 is called as an 8-bit processor since its data length is 8-bit and has a data bus of 8-bits wide. It has an addressing capability of 16-bit. i.e., it can address 216 = 64 K bytes of memory (1 K byte =1024 byte).8085 consists of various units and each unit performs its own functions. The various units of a microprocessor are listed below · Accumulator · Arithmetic and logic Unit · General purpose register · Program counter · Stack pointer · Temporary register · Flags · Instruction register and Decoder · Timing and Control unit · Interrupt control · Serial Input/output control ·...