PowerPC and its Architecture

We all know that all the computers works according to their microprocessors. We come to an idea of performance of the computer based on its Processor. Each microprocessor has architecture. Examples of such architectures are Pentium IV, PowerPC etc.

Performance Optimization With Enhanced RISC – Performance Computing is abbreviated as PowerPC. As the name says, it uses the RISC architecture and was developed by the combined alliance of Apple, IBM and Motorola popularly known as “AIM”. It was developed in the year 1991. It was developed on the basis of Power (Performance Optimization With Enhanced RISC) architecture which was developed by the IBM and was the fastest processor at that time.

When we go back to the history of it, IBM first developed Reduced Instruction
Set Computing (RISC) which had reduced the hardware in a great way and RISC will perform very complex operations also by using the simple operations. In the process of development of that they have developed Research Office Products Division Micro Processor which was shortly known as ROMP and used it in their workstation. Though it had given disappointing results, IBM then developed powerful Power architecture which used the most of RISC characteristics. Power architecture had characteristics like Register to Register operations and the instructions have fixed lengths and they are simple.  IBM had first used Power Architecture in RISC system/6000 in the year 1990. But one of the main drawback of Power Architecture is, it is a multi-chip design and to use the architecture widely, single chip design is needed. Then IBM joined hands with Apple and Motorola and developed Single chip, PowerPC architecture.

PowerPC retains the most of the Power Architecture in order to attain compatibility with the already available software and it had many enhancements to make it more efficient.  PowerPC has the superscalar processor architecture, that means it can execute several instructions at the same time. Since it is developed on single chip, it can be used in high end devices also. Since it has employed RISC architecture, the hardware of the architecture is reduced hence, the cost of it is low. It is capable of handly multiprocessors at the same time and it is a 64 bit processor.  Power Architecture had used the instruction format with 3 operands but in PowerPC in most of fields, this 3 operand instruction format was eliminated.  In PowerPC architecture some complex string instructions which are used in Power architecture are eliminated thus making the PowerPC architecture simpler.

There are 3 types of registers present in the PowerPC architecture. They are :

  1.  General Purpose Registers :– These registers are used for all general purpose operations. All integer operations are done by these general purpose registers.

  2.  Floating-Point Registers    :– These registers are used for all the floating point operations.

 3. Special Purpose Registers :– These registers are used for special operations. For example : The Count Register (TCR) which is used to find the loop count. 

There are 3 data types used in the PowerPC architecture. They are :

 1. Fixed Point data types : These include signed and unsigned words, bytes etc. Negative values can be represented using 2’s complement method.

 2.  Floating Point data types : These include both 32 bit single precision floating point data and 64 bit double precision floating point data   

 3. Characters : 8 bit ASCII code is used to store characters.

There are many instructions used in PowerPC architecture, these instructions are also categorized in to several types such as Data movement instructions, arithmetic instructions etc. Examples are Load and store instructions come under Data movement instructions and Add, multiply will come under arithmetic instructions.  There are many instruction formats like D-form, I-form, BD-form etc . All formats are 32-bit long. 

As PowerPC architecture is very fast, it was used in several systems such as PowerPC 601, 603 etc, routers, robotics and they are even used in Video gaming like XBOX consoles etc.