Layman's Guide to Computing

[LMG S10] Issue 120: Drivers, the glue between hardware and firmware

May 15, 2021

Previously: Solid-state disks are much faster than hard disks because they have no moving parts, so no time is wasted waiting for parts to get into the right...

[LMG S10] Issue 119: Solid-state disks, an upgrade from hard disks

May 8, 2021

Previously: A hard disk consists of a read arm, and a set of magnetic platters which store data. To read or write data, the read arm must move to the...

[LMG S10] Issue 118: When I run two file-copy processes at the same time, why are they much slower?

May 1, 2021

Previously: Operating systems use a page file on the storage disk as a complement to physical memory. This allows OSes to behave more performantly than they...

[LMG S9] Issue 117: Swap space

April 24, 2021

Previously: Hibernation mode causes the computer to store the data configuration into a hibernation file on disk. When powered up, the OS reads the data...

[LMG S9] Issue 116: Hibernation

April 17, 2021

Previously: When you shut a computer down, it sends an exit signal to all running programs to get them to do their exit routine. This process can sometimes...

[LMG S9] Issue 115: Shutdown & standby

April 10, 2021

Previously: Embedded operating systems are unlike user operating systems. They are designed to run the software needed for an appliance’s operation, and are...

[LMG S9] Issue 114: In the beginning (firmware)

April 3, 2021

Previously: If you can’t get to a BIOS screen, it is likely a hardware problem and has to be solved by a technician. If you can’t get the the OS loading...

[LMG S9] Issue 113: A computer’s existential crisis (boot failure)

March 27, 2021

Previously: When a computer is booted up, it runs the BIOS from a chip on the motherboard. The chip checks that core parts are present, checks for a storage...

[LMG S9] Issue 112: Bootstrapping into existence (bootup)

March 20, 2021

Previously: Moving a file (within the same disk region) merely updates its file table record, and this happens really quickly. Copying a file, or moving it...

[LMG S9] Issue 111: Copying, moving, and deleting files

March 13, 2021

Previously: Filesystem journals are a record of changes made to the disk, so as to enable those changes to be rolled back, or to be completed properly in...

[LMG S9] Issue 110: Safeguarding against data corruption with a journal

March 6, 2021

Previously: Fast writes dump the data to a write cache (in computer memory), then update the file table to look like the file is already written to disk....

[LMG S9] Issue 109: Speeding up data operations

February 27, 2021

Previously: Safe writes ensure that all the data is written to disk sectors properly first before updating the file table. The result is that write...

[LMG S9] Issue 108: Safeguarding data operations

February 20, 2021

Previously: When write operations are interrupted prematurely, filesystem corruption often results. When a batch of data (shipment of cargo)) arrives at our...

[LMG S9] Issue 107: The challenges of storage

February 13, 2021

Previously: A hard disk is organised into sectors, which are the smallest unit of storage. The OS’s filesystem determines how and where to store each file on...

[LMG S9] Issue 106: Organising storage

February 6, 2021

Previously: The OS takes care of booting up, login and user management, window management, memory allocation, storage interfaces, background services,...

[LMG S9] Issue 105: Operating Systems

January 30, 2021

Previously: Shared secrets allow secured access to resources, such as databases or other services. These shared secrets are typically kept on a server...

[LMG S8] Issue 104: Storing sensitive data

January 23, 2021

Previously: A race condition happens when threads depend on instructions happening with coincidental timing for success. When instructions are not executed...

[LMG S8] Issue 103: Why apps hang even with multiple threads

January 16, 2021

Previously: Applications are assigned a thread by the OS for running a sequence of instructions. The instructions are executed sequentially, and the app...

[LMG S8] Issue 102: Threading

January 9, 2021

Previously: An app crashes when it encounters a situation it can’t handle, or when it attempts to perform an operation that is disallowed by the operating...

[LMG S8] Issue 101: Why apps crash

January 2, 2021

Previously: Windows systems categorise data into two types: files, and settings. Files are stored under an appropriate subfolder in C:\, while other storage...

[LMG S8] Issue 100: Where does all the app data go? A look at Windows systems

December 26, 2020

Previously: MacOS, Linux, and other similar systems treat everything as a file, organised into appropriate subfolders. Previous issue: Mac- and Linux-like...

[LMG S8] Issue 99: Where does all the app data go? A look at Mac-like systems

December 19, 2020

Previously: Apps generally handle three categories of files: its own (permanent) app files, (shared) user files, and (ephemeral) temporary files. What we are...

[LMG S8] Issue 98: Temporary files

December 12, 2020

Previously: A laptop app can do practically anything, if it is running through the Administrator/root account. Sandboxing is carried out through permission...

[LMG S8] Issue 97: Laptop apps

December 5, 2020

Previously: Mobile apps are sandboxed by the operating system. As a result, they have to bundle all the libraries they need, and are not allowed to share...

[LMG S8] Issue 96: Why are mobile apps so large in size?

November 28, 2020

Previously: Mobile apps, unlike web apps, can bundle resources and libraries to be installed to a mobile device. They can also request access to storage, and...

[LMG S8] Issue 95: What’s in a mobile app?

November 21, 2020

Previously: Web apps require the browser to request memory on their behalf, and thus their memory usage shows up under the browser process in the OS Task...

[LMG S8] Issue 94: Why do web browsers take up so much memory?

November 14, 2020

Previously: Web apps have limited access to the device’ storage, and can only store data in browser-managed databases. Progressive Web Apps (PWAs) can...

[LMG S8] Issue 93: What's in a web app?

November 7, 2020

Previously: Sandboxing is a catch-all term for the concept of ensuring apps don’t have access to resources outside of their privileges. Sandboxed apps are...

[LMG S8] Issue 92: All about apps

October 31, 2020

Previously: Depending on what you need a database for, there may be online database platforms that can manage and automate much of the work for you....

[LMG S7] Issue 91: Commercial database alternatives

October 11, 2020

Oops, I misscheduled this week’s issue and it didn’t go out yesterday as it should have 🙈 sorry about that! Previously: A URI (Uniform Resource Identifier)...

[LMG S7] Issue 90: Using a database

October 3, 2020

Previously: Graph databases treat the details of things as secondary, and optimise for managing the network of relationships. A graph database can quickly...

[LMG S7] Issue 89: Graph Databases

September 26, 2020

Previously: Document databases organise data into documents, each containing a number of field-value pairs. each value can itself be a document, and multiple...

[LMG S7] Issue 88: Document Databases

September 19, 2020

Previously: Relational databases are designed to maintain a well-structured set of data tables through constraint rules. This makes them very useful for...

[LMG S7] Issue 87: Relational Databases

September 12, 2020

Previously: To increase the performance of a distributed database, we can scale up/scale vertically by increasing the computers’ performance, or scale...

[LMG S7] Issue 86: Distributed databases

September 5, 2020

Previously: Forms that naïvely inject user-submitted data into a SQL query template may end up sending valid SQL commands to the database, with disastrous...

[LMG S7] Issue 85: SQL Injections

August 29, 2020

Previously: SQL queries let you join multiple tables based on specified conditions using the JOIN keyword. This enables crafting complex queries to return...

[LMG S7] Issue 84: JOIN – supercharged VLOOKUP

August 22, 2020

Previously: Structured Query Language (SQL) is a computer language for managing data in databases. It has keywords and keyphrases that let you filter rows...

[LMG S7] Issue 83: Structured Query Language

August 8, 2020

Previously: A database system follows rules that enable multiple users to send commands to the database at the same time. The system attempts to execute each...

[LMG S7] Issue 82: Multiplayer databases

August 1, 2020

Previously: Putting all data into one table results in unnecessary duplication of data. Making data atomic by splitting it up into multiple tables makes the...

[LMG S7] Issue 81: Data Normalisation

July 25, 2020

Previously: An index is a separate table containing key terms in the database (usually names, IDs, or some other key identifier), alongside the row numbers...

[LMG S7] Issue 80: Indexing

July 18, 2020

Previously: Comma-separated value (CSV) files store all data in text form. Within each row, a separator divides each chunk of data, and rows are separated by...

[LMG S7] Issue 79: A Base for Data

July 11, 2020

Previously: Modern webpages rely on many third-party resources for their functionality. Blocking access to some domains may cause these webpages to break and...

[LMG S6] Issue 78: uMatrix: voyuering the voyeurs

July 4, 2020

I belatedly realised that this issue was mis-scheduled, which is why there wasn’t an issue last week. My apologies! Previously: The default settings of most...

[LMG S6] Issue 77: Wearing clothes on the Internet

June 20, 2020

Previously: Cookies with the same domain as the site are first-party cookies, while cookies with domains different from the site are third-party cookies....

[LMG S6] Issue 76: Third-parties and cross-site resources

June 13, 2020

Previously: By not enforcing strict cookie policies on their own sites, publishers allowed advertisers to sneakily set cookies on their site audience. This...

[LMG S6] Issue 75: The Costs of Data Leakage

June 6, 2020

Previously: Data companies use the data they have gathered to determine what ads to serve you when you visit sites that load their cookie-setting scripts....

[LMG S6] Issue 74: The Walls Have Pixels

May 30, 2020

Previously: When a page loads advertisements through header bidding, it sends your cookie along with other information to an ad exchange. The ad exchange...

[LMG S6] Issue 73: The Heart of Darkness (Header Bidding)

May 23, 2020

Previously: QuantCast gathers a large amount of data on internet users directly through its cookie (which other publishers serve through their websites), and...

[LMG S6] Issue 72: The Data Brokers

May 16, 2020

Previously: In 2006, Quantcast offered complete audience analytics for any site that puts their cookie on the site. In this way, they managed to gather...

[LMG S6] Issue 71: The Rise of Audience Analytics

May 9, 2020

Previously: A tracking script retrieves the existing cookie on a web domain if there is one, or sets a cookie on a webpage if there isn’t an existing one....