8085 Microprocessor Basic information & How its work
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The 8085 microprocessor is a programmable device that takes in binary data, performs arithmetic or logical operations according to instructions stored in memory, and produces results. It uses registers like the accumulator, program counter, stack pointer, and general purpose registers. Memory, including ROM and RAM, stores instructions and data for the microprocessor. Assembly language uses mnemonics like "INR A" and "ADD B" to represent machine code instructions in a more readable way.
8085 Microprocessor Basic information & How its work
- 1. 8085 Microprocessor Basic information & How its work Othman M.Hussein M.Ali & Haider Saleem Faculty of Engineering University of Kufa
- 2. Basic Concepts of Microprocessors • Differences between: – Microprocessor. – Microcontroller. Definition of the Microprocessor The microprocessor is a programmable device that takes in numbers, performs on them arithmetic or logical operations according to the program stored in memory and then produces other numbers as a result. MicroprocessorMicrocontroller
- 3. Memory • Memory stores information such as instructions and data in binary format (0 and 1). It provides this information to the microprocessor whenever it is needed. – Read Only Memory (ROM) – Random Access Memory (RAM) (also known as Read/Write Memory).
- 4. • Registers – General Purpose Registers • B, C, D, E, H & L (8 bit registers) • Can be used singly Or can be used as 16 bit register pairs – BC, DE, HL – Special Purpose Registers • Accumulator (8 bit register) – Store 8 bit data – Store the result of an operation – Store 8 bit data during I/O transfer
- 5. • The Program Counter (PC) – This is a register that is used to control the sequencing of the execution of instructions. – This register always holds the address of the next instruction. – Since it holds an address, it must be 16 bits wide. • The Stack pointer – The stack pointer is also a 16-bit register that is used to point into memory. – The memory this register points to is a special area called the stack. – The stack is an area of memory used to hold data that will be retrieved soon.
- 6. The 8085 Machine Language Because it is very difficult to enter the bit patterns correctly, they are usually entered in hexadecimal instead of binary. • For example, the combination 0011 1100 which translates into “increment the number in the register called the accumulator”, is usually entered as 3C. Assembly Language – However, it still is difficult to understand what a program written in hexadecimal does. So, each company defines a symbolic code for the instructions, These codes are called “mnemonics”. – The mnemonic for each instruction is usually a group of letters that suggest the operation performed.
- 7. Using the same example from before, – 00111100 translates to 3C in hexadecimal (OPCODE) – Its mnemonic is: “INR A”. – INR stands for “increment register” and A is short for accumulator. • Another example is: 1000 0000, – Which translates to 80 in hexadecimal. – Its mnemonic is “ADD B”. – “Add register B to the accumulator and keep the result in the accumulator
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