The Advent of Digital Signal Processors

A DSP is a specialized microprocessor optimized for the needs of digital signal processing. Their goal is usually to filter, compress or measure real-world analog signals.

Most CPUs can run DSP logic effectively but the rise in DSP specialized processors is due to their power-efficiency and consequent applicability to mobile phones. They use special memory architectures enabling efficient parallel processing.

Multiply-accumulate operations feature heavily in DSP chips. Multiply-accumulate refers to multiplying two numbers and adding the output to an accumulator. Hardware that does this is known as a MAC, or MAC unit, and the operation is known as a MAC operation. It therefore computes and stores the value of a+(b*c) in the accumulator a. When performed with two floating point numbers, it can be performed with 2 roundings, or 1 rounding, the later known as fused multiply-add (FMA) or fused multiply-accumulate (FMAC).

Qualcomm's Snapdragon chip has DSP modules built in. 

The Itanium Architecture and What it Tries to Achieve

Itanium's architecture is explained here. But just for handy reference, here are the main highlights.

ia64 -

GOAL NUMERO UNO - is to support 64 bit addressing and 64 bit data types

Peformance and ease of use are obvious secondary goals. But also ease of interfacing with IA-32 is an important design goal.

The Usefulness of Semiconductors in Computers

Why are semiconductors so critical and useful in building computers?

First off, let's revise what a semiconductor actually is. A semiconductor (such as silicon, germanium and gallium arsenide) have conductivity in between a good conductor (metal such as copper) and an insulator (think of it as a mean value theorem type result applied to electrical conductivity). Why is that useful?  To understand this, contemplate the following ditty praising the usefulness of semiconductors:

"Black and White are Boolean True,
But semiconductors have interim hue".

Semiconductor conductivity can be adjusted by a process known as doping; involving adding impurities into "the crystal lattice". This in turn allows the creation of p-n junctions, which are then used to create transistors and diodes.

More about p-n junctions

P-n junctions are the boundary between p-type and n-type semiconductors.  The are used to produce diodes that allow current to flow in one direction but not the other. Bias means applying a voltage across a p-n junction, forward bias means applying it in the direction of easy current flow, and reverse bias applying it in the opposite direction. In forward bias, the p-side is connected to the positive terminal of the battery and the n-side is connected to the negative terminal.

Transistors

The creation of transistors came eight years after the creation of PN barriers. Transistors can act as electronic switches in off/on state.

Logic Gates

Logic gates are created with diodes and transistors.

Now we have established why semiconductors are important, we can review some of the key milestones in their discovery and development that yielded the modern computer revolution.

1939 - Russell Ohl discovers the "PN barrier" later to be termed "PN junction". All diodes including LEDs are descendants of Ohl's work.

1947 - John Bardeen, Walter Brattain and William Shockley develop the transistor
1951 - Manufacture of transistors
1958 - First semiconductor Integrated Circuit

Where can we find more information about semiconductors and their role in business and society at large?

One useful source is the Semiconductor Industry Association (SIA).

Basic Terms and Concepts Defined

Von Neumann Model - Input Device, Output Device, CPU and Main Memory
Turing Machine - theoretical computer with infinite memory
Harvard Architecture - separate storage and pathways for instruction and data
MIPS - millions of instructions per second
MFLOPs - millions of floating point operations per second
Logic gates - physical device implementing a Boolean function: combines or more logical inputs into a single logical output
EDVAC - one of the world's earliest electronic computers
Integrated Circuit (IC) - bunch of electronic circuits on a single chip (several billion transistors in a very small surface area)
Switch - in electrical engineering, a switch is a component that can break an electrical circuit.