# HW 3: Time for a Time Out!¶

Warning

At the bottom of this assignment are instructions telling you how to set up the file to submit. Not doing that properly will result in no credit!

We need to understand some time sensitive terminology, and get a feel for speed!

In this course, you are going to see just how fast things move inside your system. To make sense of this, you will do a bit of research on the Internet to come up with the numbers.

## How to do this homework¶

Warning

Get in the habit of reading assignments carefully. There are many things you need to do to complete each assignment properly. If needed, take a red pen and underline every requirement in this assignment. Before you submit it for grading, review your list and check off every line you underlined to be sure you did the job correctly.

To complete this homework, you will need to dig some numbers out from the Web, and calculate other numbers. For each number you use as an answer, I want a reference (URL) showing where you found the information, or the expression you evaluated with the calculator (something like 5280*12). Show that information in parentheses after your answer. If you get several answers from a single reference, include that reference only once.

## Some background¶

First, it is important to understand that our computers are driven by electricity, which you might think of as the flow of electrons through wires. Actually, it is the movement of an electromagnetic wave that is important, not the movement of electrons themselves. In doing your research, you might discover that electrons do not move much, but those waves really fly!

## What You Need to Determine¶

Warning

You will need a calculator to do this work, in addition to data from the Web!

Here are the pieces of information I want you to locate. You need to edit the places where <??> is shown below. (leave the angle brackets in place,they are used in grading):

### Basic measurement units:¶

• 1 meter = <??> inches
• 1 mile = <??> feet
• 1 mile = <??> meters
• Circumference of the Earth = <??> miles

### Basic terminology¶

We prefix numbers in the world of science with some basic terms. Determine what these mean:

• yotta something = <??> times something
• kilo something = <??> times something
• <??> something = 100 times something
• <??> something = 10 times something
• something = something (duh!)
• milli something = 1/<??> of something
• micro something = 1/<??> of something
• nano something = 1/<??> of something
• <??>something = 1/1000000000000 of something

### From Physics¶

• What is the speed of light

• = <??> mps (miles per second)
• = <??> kps (kilometers per second)

### Speed of Electronic Signals¶

Assuming electronic waves move through wire at the speed of light:

• How far an electronic signal can move through a wire:

• In one nanosecond = <??> inches
• In one microsecond = <??> feet
• In one millisecond = <??> miles
• In one second = <??> miles
• In one second = <??> times around the Earth!

### From our World of Processors¶

One last piece of the puzzle. I would like to see if you can figure out how fast a signal moves between transistors in a typical Pentium processor. To figure that out, we need to figure out how far apart they are. We will keep this simple.

We will look at numbers for the Intel Haswell line of processors. Unfortunately, most manufacturers use the metric system to report how big (or small) things are, so all of the numbers in this section will be in meters (or smaller).

Dig out data for the Haswell Processor. Specifically, use this version:

• Intel i7-7700, 7th Generation Pentium chip

• Manufacturing Process = <??>nm
• Transistor Count = <??> transistors
• Die Size: <??>mm^2

Lookup this information on the chip:

• Number of cores = <??>
• Number of threads = <??>
• Maximum (turbo) clock frequency = <??> GHz.
• Maximum memory = <??> GB.

Assuming that the chip is square, and that there are, say, 1,400,000,000 transistors on the chip, we can take the square root of 1.4 billion to see how many transistors must be on each side of the square. If the actual chip has a surface area of 264 square millimeters, figure out how long each side is, and using your numbers from above, figure out how long it takes for an electronic signal to move the distance between two adjacent transistors. (Be sure to check the equation you used to figure this out. Many students mess this one up!)

• Distance between transistors = <??> nanometers.

As a check (ballpark, at least), see if your calculations match the manufacturer’s current technology. They report their ability to squeeze transistors together in nanometers. Are your numbers close?

Note

Remember that there must be room for all the “wires”, actually called traces, needed to move signals from one place to another. So, it might seem like there is plenty of room left for that, in actual fact, we are reaching the limits on how small we can manufacture things. That is, unless we come up with a new technology!

Finally, calculate the time it will take for an electron to move between two adjacent transistors.

• Time to move electrons between adjacent transistors = <??> picoseconds.

## Counting up¶

As a last bit of trivia, lets see how big a 64-bit integer really is.

The current Pentium processor uses 64-bit “registers”. Assuming your processor is ticking away at a rate of 2.7 GHz, how long will it take to reach the biggest number the register can hold (Hint: the biggest number is 2^64 - 1):

• Time until the register hit the maximum value = <??> years

## References¶

Remember to include documentation on your sources.

## What to turn in¶

The file you submit is to be written using the reStructuredText markup language.