IC Technolgy

Before we go in detail of IC technology first of all we have to understand what is IC,IC directly implies the Integrated Circuit.An IC,often called a chip,is a semiconductor device consisting of a set of connected transistors and other devices.Every processor must eventually implemented on an integrated circuit(IC).IC technology involves the manner in which we map a digital implementation onto an IC.A number of different processes exists to build semiconductor,the most popular of which is complementary metal oxide semi conductor(CMOS).IC technology is independent from processor technology that means any type of processor can be mapped to any type of IC technology.Now the main question that arises in front of us is what are the differences between the different IC technologies.

To understand the difference between different IC technologies we must first recognize that semiconductors consists of numerous layers.The bottom layers form the transistors.The middle layers form logic components.The top layers connect these components with wires.One way to create these layers is by depositing photo-sensitive chemicals on the chip surface and then shining light through masks to change region of the chemicals.Thus,the task of building the layers is actually one of designing appropriate masks.A set of masks is often called layout.

Single Purpose Processors

A single purpose processor is a digital circuit designed to execute exactly one program.An embedded system designer may create a single purpose processor by designing a custom digital circuit.Alternatively,the designer may purchase a predesigned single purpose processor.Many people refer to this part of the implementation simply as the hardware portion,although even software requires a hardware processor on which to run.A single purpose processor when used in embedded systems,it has both advantages and disadvantages over the general purpose processors.If we look at the advantages of the single purpose processor,then by using single purpose processor performance may be fast,size is small,less power consumption and low unit cost for large quantities.On the other hand its disadvantages are very high design time,high NRE costs,low flexibility and high unit cost for small quantities.

General Purpose Processors

A general purpose processor is a programmable device that is suitable for a variety of applications.The most important feature of these processors is program memory,that means the designer of such processors does not know what program will run on that processor,so the program cannot be built into the digital circuit.Another important feature of these processors is general datapath that means the datapath must be general enough to handle a variety of computations,so such a datapath typically has a large register file and one or more general purpose arithmetic logic units(ALUs).An embedded system designer,however need not be concerned about the design of general purpose processor.An embedded system designer simply uses a general purpose processor,by programming the processor's memory to carry out the required functionality.Using a general purpose processor in an embedded system may result in several design benefits.