Super computer

A commercial computer with vector instructions and pipelined floating point arithmetic operations is referred to as a super computer.Super computers are very powerful,high performance machines used mostly for scientific computations.super computers also use special techniques for removing the heat from circiuts to prevent them from burning up because of their close proximity.super computers are suitable for normal everyday processing of a typical computer installation.

Parallel processing

Parallel processing is a term used to denote a large class of techniques that are used to provide simultaneous data processing tasks for the purpose of increasing the computational speed of a computer system.Instead of processing each instruction sequentially as in a conventional computer , a parallel processing system is able to perform concurrent data processing to achieve faster execution time.for example while an instruction is being executed in the alu the next instruction can be read from memory . The system may have two or more alu 's and be able to execute two or more instructions at the same time.furthermore the system may have two or more processors operating concurrently.The purpose of parallel processing is to speed up the computer processing capability & increase its throughput,that is the amount of processing that can be accomplished during a given interval of time .The amount of hardware increases with parallel processing and with it the cost of the system increases.

Cisc

The design of an instruction set for a computer must take into consideration not only machine language constructs but also the requirements imposed on the use of high level programming languages .The translation from high level to machine level programs is done by means of  a compiler program.one reason for  the trend  to provide a complex instruction set  is the desire to simplify the compilation and improve the overall computer performance.
The task of a compiler is to generate a sequence of machine instructions for each high level language statement.
The task is simplified if there are machine instructions that implement the statements directly.The essential goal of a cisc architecture is to attempt to provide a single machine instruction for each statement that is written in a high level language.examples of cisc architectures are the digital equipment corporation VAX computer and the IBM 370 computer .
Another characteristic of cisc architecture is the incorporation of variable length instruction formats

Reduced instruction set computer

An important aspect of computer architecture is the design of the instruction set for the processor.The instruction set chosen for a particular computer determines the way that machine language programs are constructed .
early computers had small and simple instruction sets forced mainly by the need to minimize the hardware used to implement them.as digital hardware became cheaper with the advent of integrated circuits ,computer instructions tended to increase both in number  and complexity.Many computers have insruction sets that include more than 100 and some times even more than 200 instructions.
These computers also employ a variety of data types and a large number of addressing modes. 

Arithmetic and logic operations

The number of instructions available in a computer may be a few hundred in a large system or a few dozen in a small one.Some computers perform a given operation with one machine instruction;others may require a large number of machine instructions to perform the same operation  . Some computers have machine instructions to add,subtract,multiply and divide.others such as the basic computer have only one arithmetic instruction,such as add.operations not included in the set of machine instructions must be implemented by a program.
operations that are implemented in a computer with one machine instruction are said to be implemented by hardware.operations implemented by a set of instructions that constitute a program are said to be implemented
by software.some computers provide an extensive set of hardware instructions designed to speed up common tasks .others contain a smaller set of hardware instructions and depend more heavily on the software implementation of many operations

Assembly language

A programming language is defined by a set of rules.Users must conform with all format rules of the language if they want their programs to be translated correctly.Almost every commercial computer has its own particular assembly language.The rules for writing assembly language programs are documented and published in manuals which are usually available from the computer manufacturer.
The basic unit of an assembly language program is a line of code.The specific language is defined by a set of rules that specify the symbols that can be used and how they may be combined to form a line of code.we will now formulate the rules of an assembly language for writing symbolic programs for the basic computer.

Machine language

A program is a list of instructions or statements for directing the computer to perform a required data processing task.There are various types of programming languages that one may write for a computer,but the computer can execute programs only when they are represented internally in binary form. programs written in any other language must be translated o the binary representation of instructions before they can executed by the computer.
binary code: this is a sequence of instructions and operands in binary that list the exact representation of instructions as they appear in computer memory.
octal or hexadecimal code: this is n equivalent translation of the binary code to octal or hexadecimal representation

Bus and Memory Transfers

A typical digital computer has many register and paths must be provided to transfer information from one register to another . The number of wires will be excessive if seperate lines are used between each register and all other registers in the system.A more efficien scheme for transferring information between registers in a multiple register configuration is a common bus system. A bus structure consists of a set of common lines one for each bit of aregister, through which binary informatio is transferred one at  a time .control signals determine which register is selected by the bus during each particular register transfer.
one way of constructing a common bus system is with multiplexers.The multiplexers select the source registre whose binary information is then placed on the bus.

Computer register are designated by capital letters to denote the function of the register.for example ,the register that holds an address for the memory unit is ususlly called a memory address regster and is designated by the MAR.other designations for register are PC ,IR and R1 . The indivdual flip flops in an n-bit register are numbered in sequence from 0 through n-1,starting from 0 in the rightmost position and increasing the numbers toward the left.The most common way to repreent a register is  by a rectangular box with the name of the register inside.Information transfer from one register to another is designated in symbolic form by means of a replacement operator.

Register Transfer Language

A digital system is an interconnection of digital hardware modules that accomplish a specific information -processing task. Digital systems vary in size and complexity from a few integrated circuits to a complex of interconnected and interacting digital computers.Digital system design invariably uses a modular approach.The modules are constructed from such digital components as registers,decoders,arithmetic elements and control logic.The various modules are interconnected with common data and control paths to form a digital computer system.Digital modules are best defined by the registers they contain and the operations that are performed on the data stored in them.The operations executed on data stored in registers are micro operations.A micro operation is an elementary operation performed on he information stored in one or more registers.