Inside a Computer and Binary

In this week’s classes, we learned what is inside a computer to see how it works by going deep into the role of CPU and the binary system. To understand that better, we did two roleplaying activities to imitate how the CPU and the binary number system work. We also practiced how to convert binary to and from decimal.

Functions of CPU, CU, ALU, Register, and Bus

CPU refers to the Central Processing Unit which is like the brain of a computer. It fetches and executes a sequence of stored instructions called a program from the memory. CU refers to Control Unit which decides and tells other parts of the CPU what to do. It also controls the work time and the instructions sent to the processor and peripheral devices. ALU refers Arithmetic Logic Unit which does the calculations (arithmetic) and deals with logic in a computer. The Register functions as a memory storage location within a CPU but it can only store memory temporarily. The Bus carries the message to communicate with other parts of the computer.

How Does a Computer Work

When you click your mouse, you send the input message to the computer. When your message is received, it would be handled by the basic input-output subsystem. This subsystem would then send a message to the CPU to process it. The CPU would fetch and execute these instructions from memory. Within the CPU, CU fetches information from the Register and memory and tells ALU what to do through the Bus. After ALU has done its calculations, it would send the result by the Bus to display it on your screen as the output.

Binary Number System

Before talking about the binary number system, it’s quite crucial to learn about the meaning of data and information. Data can be seen as the raw materials which are the binary numbers computer works with. Information is words, numbers and pictures that human can understand. It’s unnecessary and would take too much space for computers to use the language human use, so computers use binary number system as data and convert it into information which human can read. Binary number system expresses number with only 2 symbols: generally 1 and 0. It is a positional notation with a radix of 2.

How to Convert Binary To and From Decimal

1. Write down the binary number,
2. List the powers of two from right to left,
3. Write the digits of the binary number below their corresponding powers,
4. Add the powers which have number “1” below them,
5. The final answer is the decimal way to express the binary number.

For example, for binary number 110011:

As there is the number “1” below 64, 32, 2 and 1, we add them together: 64+32+2+1=99, which 99 is the decimal way to express 110011.

Roleplaying Activities

To understand how the CPU and the binary number system better, we did 2 roleplaying activities to imitate how they work. 

In the first roleplaying activity, I played the role of the Display. I filled the boxes followed the instruction that the Bus carried to me. There were many times I found that I couldn’t fill the boxes that they told me to fill because they may not exist on the table I received or I had already filled them, but I couldn’t say anything to tell CU and ALU the error. After the roleplaying activity, I really get what it means by different components of CPU do their jobs separately and how each component communicates with the others through the Bus. I realized the importance of a pre-set method to handle errors such as what I had met. 

In the second roleplaying activity, I played the role of an ordinary audience instead of a volunteer. I watched how the addition of the dots can represent a number as the binary number system can do. Then we flipped cards to represent the “1” and “0” in the binary system to count numbers from 1 to 20 with our partners. I started to learn how to convert a binary number to decimal through these activities.

ASCII and UNICODE research

ASCII, American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Originally based on the English alphabet, ASCII encodes 128 specified characters into 7-bit integers. 95 of the encoded characters are printable: these include the digits 0 to 9, lowercase letters a to z, uppercase letters A to Z, and punctuation symbols. In addition, the original ASCII specification included 33 non-printing control codes which originated with Teletype machines. For example, lowercase i would be represented in the ASCII encoding by binary 1101001 = hexadecimal 69 (i is the ninth letter) = decimal 105.

Unicode is a computing industry standard for the consistent encoding, representation, and handling of text expressed in most of the world’s writing systems. The standard is maintained by the Unicode Consortium, and as of June 2018 the most recent version, Unicode 11.0, contains a repertoire of 137,439 characters covering 146 modern and historic scripts, as well as multiple symbol sets and emoji. 

ASCII can encode 128 characters while Unicode can encode 137,439 characters. ASCII is based on English while Unicode allows computers to be multilingual since it can express text in most of the world’s writing systems. It is very interesting to notice that the first 128 Unicode code points are the ASCII characters.