Microprocessor 8085/8086 Lecturer M A Rahim Khan Computer Engineering and Networks Deptt.

General Definitions A Computer is a programmable machine. The two principal characteristics of a computer are: It responds to a specific set of instructions in a well defined manner. It can execute a prerecorded list of instructions (program). Modern computers are electronic and digital. The actual machinery wires, transistors, and circuits is called hardware. The instructions and data are called software.

General Definitions (cont..) Computers can be generally classified by size and power as follows. Personal computer: A small, single-user computer based on a microprocessor. In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving data. Working station : A powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a higher-quality monitor.

General Definitions (cont..) Minicomputer : A multi-user computer capable of supporting from 10 to hundreds of users simultaneously. Mainframe : A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously. Supercomputer : An extremely fast computer that can perform hundreds of millions of instructions per second.

General Definitions (cont..) Embedded system: A specialized computer system that is part of a larger system or machine. Typically, an embedded system is housed on a single microprocessor board with the programs stored in ROM. Virtually all appliances that have a digital Interface watches, microwaves, VCRs, cars -utilize embedded systems. Some embedded systems include an operating system, but many are so specialized that the entire logic can be implemented as a single program.

General Definitions (cont..) Micro Controller Micro Processor It is a single chip It is a CPU Consists Memory, Memory, I/O Ports to I/O Ports be Connected externally

8085 Microprocessor The salient features of 8085 μp are : It is a 8 bit microprocessor. It has 16 bit address bus and hence can address up to 216 = bytes (64KB) memory locations through A0-A15. The first 8 lines of address bus and 8 lines of data bus are multiplexed AD0 – AD7.

8085 Microprocessor ( cont..) Data bus is a group of 8 lines D0 – D7. It supports external interrupt request. A 16 bit program counter (PC) A 16 bit stack pointer (SP) Six 8-bit general purpose register arranged in pairs: BC,DE, HL. It requires a signal +5V power supply and operates at MHZ single phase clock. It is enclosed with 40 pins DIP ( Dual in line package ).

8085 Microprocessor ( cont..) Memory: Program, data and stack memories occupy the same memory space. The total addressable memory size is 64KB. Program memory – memory. Jump, branch and call program can be located anywhere in instructions use 16-bit addresses, i.e. they can be used to jump/branch anywhere within 64 KB. All jump/branch instructions use absolute addressing.