Digital Electronics and Microprocessor - I

The 8085 is an ____ general purpose microprocessor that can address _____ Kbyte of memory.

8-bit, 64

M-8085: It has ____ pins and uses _____ for power. It can run at a max frequency of 3 MHz.

40, +5V

The pins on the chip can be grouped into 6 groups:

1. address bus

2. data bus

3. control and status signal

4. power supply and frequency

5. Externally initiated signals

6. Serial I/O ports

M-8085: List the 3 register types

1. Temporary Register

2. General Purpose Register

3. Special Purpose Register

There are _____, ______(W and Z) temporary registers used to hold 8-bit data/address during execution of some instructions.

2, 8-bit

General purpose registers:

B,C,D,E,H,L

The ________ pair workds as a memory pointer.

H-L

General purpose registers can hold _____ data. Apart from that function these registers can also be used to work in pairs to hold _________ data.

8-bit, 16-bit

Memory pointer holds the _____________________________.

address of a particular memory location

Special purpose registers:

1. Accumulator

2. Status or Flag register

3. Instruction register

4. program counter

5. stack pointer

The ____________ is an 8-bit register that is part of the ALU.

Accumulator

The accumulator is used to store _____ data and to perform _______________.The result of the operation is stored in the accumulator.

8-bit, arithmetic/logical operations

The _____________ also reads data from input device and similarly can transfer data to output device.

accumulator

The _________________ register is a group of flipflops used to give status of different operations result and is connected to the ______.

Status/Flag, ALU

Flags:

1. Zero(Z)

2. Carry(CY)

3. Sign(S)

4. Parity(P)

5. Auxiliary Carry (AC) flags

A ___________ register contains a number of flags either to indicate certain conditions arising after arithmetic and logical operations or to control certain operations.

flag

Program counter:

1. 16 bit register

2. deals with sequenccing the execution of instructions

3. is a memory pointer

4. holds 16 bit addresses

Stack Pointer

• 16 bit register that is used as a memory pointer

• maintains the address of the last byte that is entered into the stack

M-8085 has 3 types of instruction sets:

1. 1 byte instruction

2. 2 byte instruction

3. 3 byte instruction

the first byte is always the ___________.

Opcode

Opcode:

The ffirst part of the instruction which specifies the task to be performed.

Operand:

Is the second part of the instruction which specifies the data to be operated.

Classification of instruction sets:

1. Data transfer instructions

2. Arithmetic instructions

3. Logical instructions

4. branching instructions

5. control instructions

Duality Principle:

Interchanging the binary operators OR and AND and replacing ones with zeros and zeros with ones is called the duality principle.

Types of addressing modes:

1. Direct addressing

2. Register addressing

3. Register indirect addressing

4. Immediate Addressing

Implicit Addressing:

• These instructions operate on the content of the accumulator.

• Don’t need the address of the operand.