# Glossary

### ALU

ALU - Arithmetic Logic Unit.
Performs simple math calculations.

### ASIC

ASIC - Application Specific Integrated Circuit.
A chip designed for a specific application.

### Cache

A small memory area that holds copies of recently accessed areas of main memory. This is usually kept inside or nearby the CPU. This permits the CPU to quickly retrieve data that resides in the cache. Typically a CPU can obtain data that resides in cache in 1 cycle, while it will typically take 8 or more cycles to obtain it from mainstore.

### Wafer Cost

It's cost depends on equipment cost, process cost, service costs, quality and etc. A regular wafer is about \$1000 to \$5000. The cost fluctuates up and down from generation to generation.

### Die Cost

The cost of a wafer divided by the average number of usuable chips per wafer.

### Die Size

The size of an individual chip on a wafer. The smaller it is, the more cost effective it is.

### Hypothesis

A theory meant to be be either proved or disproved.

### Interlock

An instruction not being able to continue for some reason. An example would be where one of its operands is the result of another instructions action that hasn't completed yet.

### I-Unit

I-Unit (or I-U) Instruction Unit.
The section of a microprocessor that handles the overall execution of instructions.

### Moore, Gordon E. Doctor

Dr. Gordon E. Moore is Chairman Emeritus of Intel Corporation. Gordon cofounder Intel in 1968 and was CEO from 1979 to 1987. He is the originator of the now legendary Moore's Law, named after him in 1965, and it is still being used to this day.

### Moore's Law

Dr. Gordon E. Moore discovered that the number of transistors on a chip doubles about every 18 months. Historically, this has been found to allow computers to double their performance every 18 months.

### Opcode

Opcode - Operation Code.
Afield within an instruction that determines what operation(s) an instruction is to perform.

### Operand

A value that an instruction is to perform an operation on.

### Operating System (OS)

A program that provides services for applications. One of the main things that an operating system does is it hides machine specific details. It does this by presenting a common view of the services it provides.

### Resource

What a computer or instruction needs to perform an action.

### RR Format

RR Format - Register Register Format.
A S/370 architecture instruction format where both operands come from registers.

### RX Format

RX Format - Register Index Format.
A S/370 architecture instruction format where one of the operands comes from a register and the other operands is located in memory. Besides the normal base and displacement fields for specifying an operand located in memory, this format also allows the use of an index.

### S/370

S/370 - System 370.
An system architecture used by machines designed by IBM.

### Yield

The yield is the part of the die that is good and can be used.
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