Computer Science Quiz
Bits, bytes, binary and the machines that started it all: 15 computer science questions for curious minds.
How many bits are there in one byte?
Got a hunch? Pick the answer that feels right.
8
A byte is eight bits, which gives 256 possible values from 0 to 255. The term was coined at IBM in 1956 and became the standard unit for measuring memory and storage.
Four bits make a nibble, so a byte is exactly two nibbles, which is why one byte is written as two hexadecimal digits.
What does the acronym CPU stand for?
Got a hunch? Pick the answer that feels right.
Central Processing Unit
The central processing unit is the chip that fetches, decodes and executes instructions. It is often described as the brain of the computer, while memory and storage hold the data it works on.
Modern CPUs contain multiple cores, each able to run instructions independently, which is why a quad-core chip can juggle several tasks at once.
What does RAM stand for?
Got a hunch? Pick the answer that feels right.
Random Access Memory
Random access memory is fast, temporary working memory that the processor can read and write at any address in roughly the same time. It is volatile, so its contents vanish when the power is switched off.
The first commercial DRAM chip, the Intel 1103 of 1970, held just 1 kilobit, or 128 bytes.
What is the decimal value of the binary number 1010?
Got a hunch? Pick the answer that feels right.
10
Reading from the right, the binary digits of 1010 stand for 1 times 2, plus 1 times 8, which gives 10. The 1 and 4 columns both hold a zero and add nothing.
Binary is ancient: the Indian scholar Pingala described a two-symbol system more than 2,000 years ago, and Leibniz formalised modern binary in 1703.
In computing, what does the acronym GPU stand for?
Got a hunch? Pick the answer that feels right.
Graphics Processing Unit
A GPU is a processor built to handle the parallel maths behind rendering images, and the same design now powers much of modern artificial intelligence.
Nvidia popularised the term GPU in 1999 when it launched the GeForce 256 and called it the world's first GPU.
Hexadecimal numbers use which base?
Got a hunch? Pick the answer that feels right.
16
Hexadecimal is base 16, using the digits 0 to 9 and the letters A to F. Programmers use it because one hex digit maps exactly to four binary bits, making long binary values much easier to read and write.
Web colours such as #FF0000 for red are hexadecimal: each pair of digits sets the red, green and blue level from 0 to 255.
Who created the Linux kernel, first announced in 1991?
Got a hunch? Pick the answer that feels right.
Linus Torvalds
Linus Torvalds, then a 21-year-old student at the University of Helsinki, posted his hobby kernel to a newsgroup in August 1991. Combined with GNU tools, it grew into the operating system that now runs most servers, supercomputers and Android phones.
Torvalds also created Git in 2005 to manage Linux development, and it is now the most widely used version control system in the world.
Which British mathematician proposed the imitation game, now known as the Turing test, in 1950?
Got a hunch? Pick the answer that feels right.
Alan Turing
Alan Turing's 1950 paper Computing Machinery and Intelligence asked whether a machine could hold a text conversation well enough to be mistaken for a human. He also led codebreaking work at Bletchley Park during World War II.
The ACM's Turing Award, often called the Nobel Prize of computing, has been presented in his honour every year since 1966.
The 1947 Harvard Mark II logbook entry "first actual case of bug being found" was prompted by what?
Got a hunch? Pick the answer that feels right.
A moth
On September 9, 1947, operators found a moth trapped in a relay of the Harvard Mark II and taped it into the logbook. Grace Hopper, who worked on the machine, told the story for decades and helped popularise the term debugging.
The word bug for a mechanical fault is older than computers: Thomas Edison used it in a letter in 1878.
Moore's law, set out by Intel co-founder Gordon Moore in 1965, predicted the regular doubling of what?
Got a hunch? Pick the answer that feels right.
Transistors on a chip
Moore observed that the number of transistors on an integrated circuit was doubling roughly every year, later revised to every two years. The prediction held for decades and drove the industry's planning.
Intel's first microprocessor, the 4004 of 1971, held 2,300 transistors; Apple's M1 chip of 2020 packs 16 billion onto a single piece of silicon.
Which operating system was developed at Bell Labs in 1969 by Ken Thompson and Dennis Ritchie?
Got a hunch? Pick the answer that feels right.
Unix
Thompson and Ritchie built Unix at Bell Labs on a spare PDP-7 after AT&T pulled out of the larger Multics project. Rewritten in C in 1973, it became the ancestor of Linux, macOS, iOS and Android.
Unix time counts the seconds since midnight on January 1, 1970, a starting point known as the Unix epoch.
Which 1945 University of Pennsylvania machine is widely regarded as the first general-purpose electronic computer?
Got a hunch? Pick the answer that feels right.
ENIAC
ENIAC, the Electronic Numerical Integrator and Computer, was completed in 1945 and unveiled in February 1946. It weighed about 27 tonnes, used some 18,000 vacuum tubes and was built to calculate artillery firing tables.
Its six original programmers were all women, including Jean Bartik and Betty Holberton, whose contribution was largely overlooked for decades.
Which 1971 Intel chip is regarded as the first commercially available microprocessor?
Got a hunch? Pick the answer that feels right.
4004
The Intel 4004, launched on November 15, 1971, packed a complete 4-bit central processing unit with 2,300 transistors onto a single chip. It was originally designed for a Busicom calculator.
Federico Faggin, who led the 4004's design, later founded Zilog and created the Z80 processor used in the ZX Spectrum and Game Boy.
Which home computer, launched in 1982, does Guinness World Records list as the best-selling single desktop computer model?
Got a hunch? Pick the answer that feels right.
Commodore 64
The Commodore 64 sold an estimated 12.5 million to 17 million units, far more than any other single model. Its $595 launch price, 64 KB of memory and SID sound chip made it a games machine for a generation.
Commodore founder Jack Tramiel claimed sales of up to 30 million, a figure Guinness treats as unverified.
In the ASCII character set, which decimal code represents the uppercase letter A?
Got a hunch? Pick the answer that feels right.
65
ASCII assigns 65 to uppercase A and runs through 90 for Z. Lowercase a starts at 97, so the two cases differ by exactly 32, which is a single bit in binary.
ASCII code 32 is the space character and 48 is the digit zero, which is why sorting text by code puts digits before letters.
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All Technology quizzes →About the Computer Science Quiz
A byte holds eight bits, the letter A is number 65 in ASCII, and the first computer bug was a real moth taped into a Harvard logbook in 1947. Computer science is full of facts like these, the kind that come up in classrooms, job interviews and pub quizzes alike. This quiz gathers 15 of the best in one place.
Expect questions on hardware acronyms, binary and hexadecimal arithmetic, operating systems, famous machines such as ENIAC and Deep Blue, and the pioneers behind them, from Alan Turing to Linus Torvalds. The first few are warm-ups anyone can get, and the last few will test genuine computer nerds. Great for students, programmers and anyone curious about how computers really work.
You will find 15 multiple choice questions here, each with four options. Difficulty: Medium. Most people finish in about 6 minutes, and every answer comes with a short explanation and one extra fact worth keeping.
How to play
Read the question and pick one of the four answers. The correct answer is revealed straight away with a short explanation, then press Next question to keep going. At the end you get your score out of 15 and a full review of your round. Play again any time and the questions arrive in a fresh order. There is no timer and no account.
Good to know before you play
What topics does this computer science quiz cover?
Hardware basics such as CPU and RAM, binary and hexadecimal numbers, ASCII, operating systems like Unix and Linux, and landmark machines including ENIAC, the Intel 4004, the Commodore 64 and the first GPU.
Is this quiz suitable for beginners?
Yes. The first five questions cover basics most people meet at school, and every answer comes with a short explanation, so you learn something even when you miss one.
How many questions are there?
There are 15 multiple choice questions, each with four options. We count your score at the end and show the correct answer with a fact to remember.
Answer key: all 15 questions with explanations
- How many bits are there in one byte?
8 A byte is eight bits, which gives 256 possible values from 0 to 255. The term was coined at IBM in 1956 and became the standard unit for measuring memory and storage. Four bits make a nibble, so a byte is exactly two nibbles, which is why one byte is written as two hexadecimal digits. - What does the acronym CPU stand for?
Central Processing Unit The central processing unit is the chip that fetches, decodes and executes instructions. It is often described as the brain of the computer, while memory and storage hold the data it works on. Modern CPUs contain multiple cores, each able to run instructions independently, which is why a quad-core chip can juggle several tasks at once. - What does RAM stand for?
Random Access Memory Random access memory is fast, temporary working memory that the processor can read and write at any address in roughly the same time. It is volatile, so its contents vanish when the power is switched off. The first commercial DRAM chip, the Intel 1103 of 1970, held just 1 kilobit, or 128 bytes. - What is the decimal value of the binary number 1010?
10 Reading from the right, the binary digits of 1010 stand for 1 times 2, plus 1 times 8, which gives 10. The 1 and 4 columns both hold a zero and add nothing. Binary is ancient: the Indian scholar Pingala described a two-symbol system more than 2,000 years ago, and Leibniz formalised modern binary in 1703. - In computing, what does the acronym GPU stand for?
Graphics Processing Unit A GPU is a processor built to handle the parallel maths behind rendering images, and the same design now powers much of modern artificial intelligence. Nvidia popularised the term GPU in 1999 when it launched the GeForce 256 and called it the world's first GPU. - Hexadecimal numbers use which base?
16 Hexadecimal is base 16, using the digits 0 to 9 and the letters A to F. Programmers use it because one hex digit maps exactly to four binary bits, making long binary values much easier to read and write. Web colours such as #FF0000 for red are hexadecimal: each pair of digits sets the red, green and blue level from 0 to 255. - Who created the Linux kernel, first announced in 1991?
Linus Torvalds Linus Torvalds, then a 21-year-old student at the University of Helsinki, posted his hobby kernel to a newsgroup in August 1991. Combined with GNU tools, it grew into the operating system that now runs most servers, supercomputers and Android phones. Torvalds also created Git in 2005 to manage Linux development, and it is now the most widely used version control system in the world. - Which British mathematician proposed the imitation game, now known as the Turing test, in 1950?
Alan Turing Alan Turing's 1950 paper Computing Machinery and Intelligence asked whether a machine could hold a text conversation well enough to be mistaken for a human. He also led codebreaking work at Bletchley Park during World War II. The ACM's Turing Award, often called the Nobel Prize of computing, has been presented in his honour every year since 1966. - The 1947 Harvard Mark II logbook entry "first actual case of bug being found" was prompted by what?
A moth On September 9, 1947, operators found a moth trapped in a relay of the Harvard Mark II and taped it into the logbook. Grace Hopper, who worked on the machine, told the story for decades and helped popularise the term debugging. The word bug for a mechanical fault is older than computers: Thomas Edison used it in a letter in 1878. - Moore's law, set out by Intel co-founder Gordon Moore in 1965, predicted the regular doubling of what?
Transistors on a chip Moore observed that the number of transistors on an integrated circuit was doubling roughly every year, later revised to every two years. The prediction held for decades and drove the industry's planning. Intel's first microprocessor, the 4004 of 1971, held 2,300 transistors; Apple's M1 chip of 2020 packs 16 billion onto a single piece of silicon. - Which operating system was developed at Bell Labs in 1969 by Ken Thompson and Dennis Ritchie?
Unix Thompson and Ritchie built Unix at Bell Labs on a spare PDP-7 after AT&T pulled out of the larger Multics project. Rewritten in C in 1973, it became the ancestor of Linux, macOS, iOS and Android. Unix time counts the seconds since midnight on January 1, 1970, a starting point known as the Unix epoch. - Which 1945 University of Pennsylvania machine is widely regarded as the first general-purpose electronic computer?
ENIAC ENIAC, the Electronic Numerical Integrator and Computer, was completed in 1945 and unveiled in February 1946. It weighed about 27 tonnes, used some 18,000 vacuum tubes and was built to calculate artillery firing tables. Its six original programmers were all women, including Jean Bartik and Betty Holberton, whose contribution was largely overlooked for decades. - Which 1971 Intel chip is regarded as the first commercially available microprocessor?
4004 The Intel 4004, launched on November 15, 1971, packed a complete 4-bit central processing unit with 2,300 transistors onto a single chip. It was originally designed for a Busicom calculator. Federico Faggin, who led the 4004's design, later founded Zilog and created the Z80 processor used in the ZX Spectrum and Game Boy. - Which home computer, launched in 1982, does Guinness World Records list as the best-selling single desktop computer model?
Commodore 64 The Commodore 64 sold an estimated 12.5 million to 17 million units, far more than any other single model. Its $595 launch price, 64 KB of memory and SID sound chip made it a games machine for a generation. Commodore founder Jack Tramiel claimed sales of up to 30 million, a figure Guinness treats as unverified. - In the ASCII character set, which decimal code represents the uppercase letter A?
65 ASCII assigns 65 to uppercase A and runs through 90 for Z. Lowercase a starts at 97, so the two cases differ by exactly 32, which is a single bit in binary. ASCII code 32 is the space character and 48 is the digit zero, which is why sorting text by code puts digits before letters.
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