Registers , System Bus & SMPS

 

Registers in Computer Architecture

Register is a very fast computer memory, used to store data/instruction in-execution.

A Register is a group of flip-flops with each flip-flop capable of storing one bit of information. An n-bitregister has a group of n flip-flops and is capable of storing binary information of n-bits.

A register consists of a group of flip-flops and gates. The flip-flops hold the binary information and gates control when and how new information is transferred into a register. Various types of registers are available commercially. The simplest register is one that consists of only flip-flops with no external gates.

These days registers are also implemented as a register file.

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Loading the Registers

The transfer of new information into a register is referred to as loading the register. If all the bits of register are loaded simultaneously with a common clock pulse than the loading is said to be done in parallel.

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Register Transfer Language

The symbolic notation used to describe the micro-operation transfers amongst registers is called Register transfer language.

The term register transfer means the availability of hardware logic circuits that can perform a stated micro-operation and transfer the result of the operation to the same or another register.

The word language is borrowed from programmers who apply this term to programming languages. This programming language is a procedure for writing symbols to specify a given computational process.

Following are some commonly used registers:

1. Accumulator: This is the most common register, used to store data taken out from the memory.
2. General Purpose Registers: This is used to store data intermediate results during program execution. It can be accessed via assembly programming.
3. Special Purpose Registers: Users do not access these registers. These registers are for Computer system,
• MAR: Memory Address Register are those registers that holds the address for memory unit.
• MBR: Memory Buffer Register stores instruction and data received from the memory and sent from the memory.
• PC: Program Counter points to the next instruction to be executed.
• IR: Instruction Register holds the instruction to be executed.

System Bus Design

• Bus is a communication channel.
• Characteristic of bus is shared transmission media.
• Limitation of a bus is only one transmission at a time.
• A bus which is used to provide the communication between the major components of a computer is called as System bus.

Computer:

System bus contains 3 categories of lines used to provide the communication between the CPU, memory and IO named as:

1. Address lines (AL)
2. Data lines (DL)
3. Control lines (CL) 

1. Address Lines:

• Used to carry the address to memory ad IO.
• Unidirectional.
• Based on width of a address bus we can determine the capacity of a main memory

Example:

2. Data Lines:

• Used to carry the binary data between the CPU, memory and IO.
• Bidirectional.
• Based on the width of a data bus we can determine the word length of a CPU.
• Based on the word length we can determine the performance of a CPU.

Example:

3. Control Lines:

• Used to carry the control signals and timing signals
• Control signals indicates type of operation.
• Timing Signals used to synchronize the memory and IO operations with a CPU clock.

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Switched-Mode Power Supply (SMPS)

Last Updated: July 17, 2020

Definition - What does Switched-Mode Power Supply (SMPS) mean?

A switched-mode power supply (SMPS) is an electronic circuit that converts power using switching devices that are turned on and off at high frequencies, and storage components such as inductors or capacitors to supply power when the switching device is in its non-conduction state.

Switching power supplies have high efficiency and are widely used in a variety of electronic equipment, including computers and other sensitive equipment requiring stable and efficient power supply.

A switched-mode power supply is also known as a switch-mode power supply or switching-mode power supply.

Techopedia explains Switched-Mode Power Supply (SMPS)

Switched-mode power supplies are classified according to the type of input and output voltages. The four major categories are:

• AC to DC
• DC to DC
• DC to AC
• AC to AC

A basic isolated AC to DC switched-mode power supply consists of:

• Input rectifier and filter
• Inverter consisting of switching devices such as MOSFETs
• Transformer
• Output rectifier and filter
• Feedback and control circuit

The input DC supply from a rectifier or battery is fed to the inverter where it is turned on and off at high frequencies of between 20 KHz and 200 KHz by the switching MOSFET or power transistors. The high-frequency voltage pulses from the inverter are fed to the transformer primary winding, and the secondary AC output is rectified and smoothed to produce the required DC voltages. A feedback circuit monitors the output voltage and instructs the control circuit to adjust the duty cycle to maintain the output at the desired level.

There are different circuit configurations known as topologies, each having unique characteristics, advantages and modes of operation, which determines how the input power is transferred to the output.

Most of the commonly used topologies such as flyback, push-pull, half bridge and full bridge, consist of a transformer to provide isolation, voltage scaling, and multiple output voltages. The non-isolated configurations do not have a transformer and the power conversion is provided by the inductive energy transfer.

Advantages of switched-mode power supplies:

• Higher efficiency of 68% to 90%
• Regulated and reliable outputs regardless of variations in input supply voltage
• Small size and lighter
• Flexible technology
• High power density

Disadvantages:

• Generates electromagnetic interference
• Complex circuit design
• Expensive compared to linear supplies

Switched-mode power supplies are used to power a wide variety of equipment such as computers, sensitive electronics, battery-operated devices and other equipment requiring high efficiency.