3. Computer systems

Performance data of a computer


When we use our computer, we don't usually think about what components or hardware it is made of. Sometimes, however, it would be helpful to know what computers are made of and where problems might arise. For example, when we have to decide on a new notebook in the jungle of offers. In the following, we will look at some of the most important components of a computer: the processor, the RAM and the hard disk.

Processor, memory and hard drive
Do I need 8 GB RAM or is only 4 GB enough? A quad-core processor or is a dual-core processor enough? Manufacturers are advertising ever larger numbers and ever more cores. But what really matters?
 
To illustrate what role the different components of a computer play or what 4 processor cores (quad-core) mean, let's compare the roles of the different components with cooks in a commercial kitchen.



Text for the video

Ein Koch

Processor
There is a lot of work to be done in a kitchen. To ensure that customers receive their food on time, the chef has to work quickly. He/she should cut the potatoes as quickly as possible, portion the rice efficiently, etc.
In a computer, this work is done by the processor. A fast processor ensures that calculations are completed quickly. This is important so that our movie or game runs smoothly and we don't have to wait forever when editing our vacation video. The higher the specified gigahertz value (GHz), the more cycles the processor runs through per second (3.2 GHz means that the processor runs through 3.2 billion switching cycles per second). A processor has several cores that can work in parallel. Gibt es an einem Abend nur eine Möhre zu schneiden, bringen natürlich auch viele Köch*innen nichts. The same applies to many  processor cores only make sense if they can also be used in parallel. We are typically talking about dual-core (2 processor cores), quad-core (4 processor cores) or octa-core (8 processor cores).

Eine Arbeitsfläche in einer Küche

Memory (RAM)
There are also plenty of work surfaces in a kitchen. These are important so that a few plates can be left half-finished before they can be delivered. In our computer, the  memory (RAM) takes on this role. If there is not enough workspace, some of the data must be moved to cabinets. If there is not enough memory, some of the data is swapped to the hard disk or written back to it.

Ein Kühlschrank

Hard drive
Large storage cupboards help to store the many supplies you have in a kitchen. A large  hard drive is then relevant for the computer if we have large video or image archives, for example. Here, speed plays a subordinate role. However, there are differences in the speed of storage: we notice it immediately if we have an SSD (SSDs (Solid State Drives) are storage media without moving parts) instead of a traditional HDD (HDDs (Hard Disk Drives) store data on rotating magnetic disks), because the computer starts up or programs load much faster.


Size of hard drives
The storage size of a hard drive (whether HDD or SSD) is typically specified in gigabytes or terabytes (you already know this from the previous chapter).
To get an idea of how much space a terabyte of storage offers, try the following calculation.



Explanation of the solution

We can store approximately 330,000 photos (at 3MB per photo).

One TeraByte corresponds to 1000 GigaBytes, each GigaByte in turn corresponds to 1000 MB. This means that we have a total of 1,000,000 MB to store our photos. In real operation, we “lose” a few GigaBytes because our computers usually calculate with a factor of 1024 (= 2 to the power of 10) GigaBytes per TeraByte etc.) instead of 1000 GigaBytes per TeraByte, 1000 MegaBytes per GigaByte, ....


This page follows ideas by Michael Hielscher and Beat Döbeli Honegger. More can be found in their presentation on informatics systems.