Announcements

Project 1b is due Monday

Tests are graded, expect them back shortly. (I was pleased with the results.)

Computer Basics

How exactly does a computer work?

Integrated Circuits

Integrated circuits (ICs) are the power source of the information revolution

When computers were made of discrete parts, wires of every transistor (3), capacitor (2), resistor (2), etc. had to be hand-connected

Labor intensive, expensive, error prone, unreliable, cumbersome, …

Integrated circuits solved that by 2 ideas

Integration -- circuits built as a unit from like parts

Photolithography -- printing process to make chips

Photolithography

Consider process for depositing wires

Remove Resist

Semiconductors

Silicon, a semiconductor -- sometimes conducts and sometimes does not

When semiconductors do and don’t conduct can be controlled

The degree to which semiconductors conduct can be enhanced

Ex.: Use control to test Thai AND cuisine

Field Effect

Charged objects are familiar -- use a nylon comb on a dry day

A charged field can control whether a semiconductor conducts or not

The plan

The control wire’s charge is the key

Neutral control wire, wire does not conduct

Charged control wire, implies wires conduct

MOS TRansistors

The field effect idea is implemented in metal-oxide-semiconductor transistors

Operation

The two cases are, the gate is neutral or the gate is charged

Computers ...

Deterministically execute instructions to process information

“Deterministically” means that when a computer chooses the next instruction to perform it is required by its construction to execute a specific instruction based only on the program and input it is given

Fetch/Execute Cycle

Computer = instruction execution engine

The fetch/execute cycle is the process that executes instructions

Anatomy of a Computer

Memory ...

Programs and their data must be in the memory while they are running

Control

The Fetch/Execute cycle is hardwired into the computer’s control, i.e. it is the actual “engine”

Indirect Data Reference

Instructions tell where the data is, not what the data is … contents change

ALU

The Arithmetic/Logic Unit does the actual computation

Input/Output

Input units move data from memory to outside world; output units bring data from outside world into memory

Most peripheral devices are “dumb” meaning that the processor assists in their operation

Disks are memory devices because they can output information and input it back again

The PC’s PC

The program counter (PC) tells where the next instruction comes from

Instructions are a word long, so add 4 to the PC to find the next instruction

Clocks Run The Engine

The rate a computer “spins around” the Fetch/Execute cycle is controlled by it’s clock rate

Current clocks run 2-3 GHz

In principle, the computer should do one instruction per cycle, but often it fails to

Modern processors try to do more than one instruction per cycle, and often succeed


	Project 1b is due Monday
		Tests are graded, expect them back shortly. (I was pleased with the results.)


Integrated circuits (ICs) are the power source of the information revolution
	When computers were made of discrete parts, wires of every transistor (3), capacitor (2), resistor (2), etc. had to be hand-connected
	Labor intensive, expensive, error prone, unreliable, cumbersome, …
	Integrated circuits solved that by 2 ideas
		Integration -- circuits built as a unit from like parts
		Photolithography -- printing process to make chips


	Silicon, a semiconductor -- sometimes conducts and sometimes does not
			When semiconductors do and don’t conduct can be controlled
			The degree to which semiconductors conduct can be enhanced
			Ex.: Use control to test Thai AND cuisine


	Charged objects are familiar -- use a nylon comb on a dry day
			A charged field can control whether a semiconductor conducts or not
			The plan

			The control wire’s charge is the key
			Neutral control wire, wire does not conduct
			Charged control wire, implies wires conduct


	The field effect idea is implemented in metal-oxide-semiconductor transistors


	The two cases are, the gate is neutral or the gate is charged


	Deterministically execute instructions to process information
			“Deterministically” means that when a computer chooses the next instruction to perform it is required by its construction to execute a specific instruction based only on the program and input it is given


	Computer = instruction execution engine
			The fetch/execute cycle is the process that executes instructions


	Programs and their data must be in the memory while they are running


	The Fetch/Execute cycle is hardwired into the computer’s control, i.e. it is the actual “engine”


	Instructions tell where the data is, not what the data is … contents change


	Input units move data from memory to outside world; output units bring data from outside world into memory
			Most peripheral devices are “dumb” meaning that the processor assists in their operation
			Disks are memory devices because they can output information and input it back again


	The program counter (PC) tells where the next instruction comes from
			Instructions are a word long, so add 4 to the PC to find the next instruction


	The rate a computer “spins around” the Fetch/Execute cycle is controlled by it’s clock rate
			Current clocks run 2-3 GHz
			In principle, the computer should do one instruction per cycle, but often it fails to
			Modern processors try to do more than one instruction per cycle, and often succeed