Topic 2 Main How Work Last Next

Day V – More on Computer Speed  +  Networks
(Day 5 is also pretty full, so there’s not much time for getting off track.  Note though that a sixth day will be for review.)

Unit-end Review of Rational:

20. How can the amount of RAM affect a computer’s speed?

The amount of RAM affects the size and number of applications that can be open at once.  But the amount of RAM can also affect the overall speed of the computer.  The more RAM there is, the more of each program can be loaded to RAM from the hard drive.  You see, even when there’s not enough room for all of an application to load in RAM memory, it may still be able to run, but with a minimum amount of the program being loaded into RAM.  Then, when other parts of the program are needed, a lot of time is wasted swapping data between the RAM and the slower hard drive.  (That’s the most common reason for the momentary spinning beach ball on a Mac.)  Better to have all of an open program loaded in RAM memory from the start.


21. So what about the hard drive itself, and overall computer speed?

One last hardware piece affecting computer speed is the hard drive itself.  If it is a conventional hard disk drive (rather than SSD), the rotational speed (measured in revolutions per minute – rpm) when reading and writing data can be a factor, though the speed is fairly standard.  But, secondly the amount of free space available on the hard drive can often affect computing speed.  Fragmentation of files when a hard drive is just about full can be an issue, since the file cannot be read easily from one place - though modern operating systems do a good job of "optimizing" this situation. Another problem can be when there is not a lot of room left virtual memory. "Virtual memory" is where part of the hard drive can used as if it were RAM. Again, modern computers do a good job at managing all this, but the old rule of thumb of not letting your storage get full still holds true to one extent or another.

(Analogy for fragmentation: taking a group of kids to a big stadium that is already quite full)

**See “Criteria For Buying a Desktop Computer” on for more.


22. What the heck is this "system bus", which has an affect on computer speed?

The system bus is the pathway of wires connecting the CPU to the other major components of the computer (bus actually stands for bidirectional universal switch).  So the system bus is the system of wires that transfer data around the computer (as opposed to the wires which are for power.) The speed of the system bus, just like CPU speed, is measured in Hertz (Hz) (cycles per second), with modern computers’ system buses usually operating within the range of 266 MHz to 1.6 GHz or more. But do note that though it affects a computer's speed, it's something that cannot be changed or upgraded, without changing the ertire motherboard.

(Analogy: multi-lane highway vs. a two-lane highway)


23. How do I know if I have a good graphics card?

With almost all laptop computers it is impossible to upgrade the graphics card, but Macbooks and Macbook Pros have a good one. Meantime, with a desktop computer, you are unlikely to ever consider upgrading it. But the two possible exceptions are if you play a lot of 3D computer games, or if you do a lot of video editing.  The two major brand names of higher end graphics cards are AMD (“Radeon” series), and Nvidia (“GeForce” series).  If you have either of these makes, you’re probably ready for high end graphics processing; but if you are still experiencing slower graphics rendering than you like, then you could up-grade or even add in another graphics card. You will want to maximize the amount of memory the card has; it will be up to a dozen Gigabytes in 2020.


24. What about connecting between computers, and to the Internet & speed?

Not only can patterns of 0s and 1s be transferred between different parts of the same computer, they can also be transferred between different computers within: a classroom, a school, or around the world. Transmission rate between computers within a Local Area Network (LAN) is measured in terms of the number of Megabits (not Megabytes) transmitted per second (Mbps). Our school LAN uses a network technology called Ethernet, in our case, transferring data at speeds of up to 5 Gbps within the high school building, as of mid-August 2020.

Throughput to and from the Internet is generally not as fast as through LANs.  Typical cable modem connections (which use TV cable lines), DSL connections (which use digital telephone lines) and other “broadband” technologies currently offer between 5 and 50 Mbps.  But do note that these values are theoretical upper limits, with real-time downloading and uploading being only 10-15 percent of that limit.

(Internet resource: Speedtest.net to measure the speed of your internet access at home.)


Review & Consolidation Day (useful if there will be a test)

A sixth day would be for review, with two additional activities: looking for and at related YouTube videos, and going to CNet.com to look up the specifications of various computers.

The following from the YouTube series Crash Course Computer Science makes for a great - if condensed! - summary of a lot of what has been covered by this unit.