# 0b10

Two-Bit History

Computing through
the ages

• I sometimes think of my computer as a very large house. I visit this house every day and know most of the rooms on the ground floor, but there are bedrooms I’ve never been in, closets I haven’t opened, nooks and crannies that I’ve never explored. I feel compelled to learn more about my computer the same way anyone would feel compelled to see a room they had never visited in their own home.

GNU Readline is an unassuming little software library that I relied on for years without realizing that it was there. Tens of thousands of people probably use it every day without thinking about it. If you use the Bash shell, every time you auto-complete a filename, or move the cursor around within a single line of input text, or search through the history of your previous commands, you are using GNU Readline. When you do those same things while using the command-line interface to Postgres (psql), say, or the Ruby REPL (irb), you are again using GNU Readline. Lots of software depends on the GNU Readline library to implement functionality that users expect, but the functionality is so auxiliary and unobtrusive that I imagine few people stop to wonder where it comes from.

• I once had a debate with members of my extended family about whether a computer science degree is a degree worth pursuing. I was in college at the time and trying to decide whether I should major in computer science. My aunt and a cousin of mine believed that I shouldn’t. They conceded that knowing how to program is of course a useful and lucrative thing, but they argued that the field of computer science advances so quickly that everything I learned would almost immediately be outdated. Better to pick up programming on the side and instead major in a field like economics or physics where the basic principles would be applicable throughout my lifetime.

• I recently stumbled across a file format known as Intel HEX. As far as I can gather, Intel HEX files (which use the .hex extension) are meant to make binary images less opaque by encoding them as lines of hexadecimal digits. Apparently they are used by people who program microcontrollers or need to burn data into ROM. In any case, when I opened up a HEX file in Vim for the first time, I discovered something shocking. Here was this file format that, at least to me, was deeply esoteric, but Vim already knew all about it. Each line of a HEX file is a record divided into different fields—Vim had gone ahead and colored each of the fields a different color. set ft? I asked, in awe. filetype=hex, Vim answered, triumphant.

• Github was launched in 2008. If your software engineering career, like mine, is no older than Github, then Git may be the only version control software you have ever used. While people sometimes grouse about its steep learning curve or unintuitive interface, Git has become everyone's go-to for version control. In Stack Overflow's 2015 developer survey, 69.3% of respondents used Git, almost twice as many as used the second-most-popular version control system, Subversion. After 2015, Stack Overflow stopped asking developers about the version control systems they use, perhaps because Git had become so popular that the question was uninteresting.

• Lines of code longer than 80 characters drive me crazy. I appreciate that this is pedantic. I’ve seen people on the internet make good arguments for why the 80-character limit ought to be respected even on our modern Retina-display screens, but those arguments hardly justify the visceral hatred I feel for even that one protruding 81st character.

There was once a golden era in which it was basically impossible to go over the 80-character limit. The 80-character limit was a physical reality, because there was no 81st column for an 81st character to fit in. Any programmers attempting to name a function something horrendously long and awful would discover, in a moment of delicious, slow-dawning horror, that there literally isn’t room for their whole declaration.

• I’ve always found man pages fascinating. Formatted as strangely as they are and accessible primarily through the terminal, they have always felt to me like relics of an ancient past. Some man pages probably are ancient: I’d love to know how many times the man page for cat or say tee has been revised since the early days of Unix, but I’m willing to bet it’s not many. Man pages are mysterious—it’s not obvious where they come from, where they live on your computer, or what kind of file they might be stored in—and yet it’s hard to believe that something so fundamental and so obviously governed by rigid conventions could remain so inscrutable. Where did the man page conventions come from? Where are they codified? If I wanted to write my own man page, where would I even begin?