Keyboards & Command Line Interfaces: Crash Course Computer Science #22

Key Takeaways

[Music] hi I'm Kian and welcome to crash course computer science we've talked a lot about inputs and outputs in this series but they've mostly been between different parts of a computer like outputting data from Ram or inputting instructions to a CPU we haven't discussed much about inputs coming from humans we also haven't learned how people get information out of a computer other than by printing or punching it onto paper of course there's a wide variety of input and output devices that allow us users to communicate with computers they provide an interface between human and computer and today there's a whole field of study called human computer interaction these interfaces are so fundamental to the user experience that they're the focus of the next few [Music] episodes as we discussed at the very beginning of the series the earliest mechanical and electr mechanical Computing devices use physical controls for inputs and outputs like gears knobs and switches and this was pretty much the extent of the human interface even the first electronic computers like Colossus and eniac were configured using huge panels of mechanical controls and Patch wires it could take weeks to enter in a single program let alone run it and to get data out after running a program results were most often printed to paper paper printers were so useful that even babage designed one for his Difference Engine and that was in the 1820s however by the 1950s mechanical inputs were rendered obsolete by programs and data stored entirely on mediums like punch cards and magnetic tape paper printouts were still used for the final output and huge Banks of indicator lights were developed to provide real-time feedback while the program was in progress it's important to recognize that computer input of this era was designed to be as simple and robust as possible for computers ease and understanding for users was a secondary concern punch tape is a great example this was explicitly designed to be easy for computers to read The Continuous nature of tape made it easy to handle mechanically and the holes could be reliably detected with a mechanical or Optical system which encoded instructions and data but of course humans don't think in terms of little punch holes and strips of paper so the burden was on the programmers they had to spend the extra time and effort to convert their ideas and programs into a language and a format that was easy for computers of the era to understand often with the help of additional staff and auxiliary devices it's also important to note that early computers basically pre-1950 had an extremely simple notion of human input yes humans input programs and data into computers but these machines generally didn't respond interactively to humans once the program was started it typically ran until it was finished that's because these machines were way too expensive to be waiting around for humans to type a command or into Data any input needed for a computation was fed in at the same time as the program this started to change in the late 1950s on one hand smaller scale computers started to become cheap enough that it was feasible to have a human in the loop that is a back and forth between human and computer and on the other hand big fancy computers became fast and sophisticated enough to support many programs and users at once what were called multitasking and time sharing systems but these computers needed a way to get input from users for this computers borrowed the ubiquitous data entry mechanism of the era keyboards at this point typing machines had already been in use for a few centuries but it was Christopher leam sches who invented the modern typewriter in 1868 it took until 1874 to refine the design and manufactory it but it went on to be a commercial success Sha's typewriter adopted an unusual keyboard layout that you know well query named for the top left row of letter keys there has been a lot of speculation as to why this design was used the most prevalent theory is that it put common letter pairings in English far apart to reduce the likelihood of tip bars jamming when entered in sequence it's a convenient explanation but it's also probably false or at least not the full story in fact querty puts many common letter pairs together like th and E and we know that sches and his team went through many iterations before arriving at this iconic Arrangement regardless of the reason the commercial success of sh's typewriter meant that the competitor companies that soon followed duplicated his design many alternative keyboard layouts have been proposed over the last century claiming various benefits but once people had invested the time to learn querty they just didn't want to learn something new this is what economists would call a switching barrier or switching cost and it's for this very basic human reason that we still use querty keyboards almost a century and a half later I should mention that querty isn't Universal there are many International variants like the French azti layout or the qu layout common in Central Europe interestingly scholes didn't Envision that typing would ever be faster than handwriting which is around 20 words per minute typewriters were introduced chiefly for legibility and standardization of documents not speed however as they became standard equipment in offices the desire for Speedy typing grew and there were two big advances that unlocked typing's true potential around 1880 Elizabeth Longley a teacher at the Cincinnati shorthand and typewriter Institute started to promote 10 finger typing this required much less finger movement than hunt and peek so he offered enhanced typing speeds then a few years later Frank mcin a federal court clerk in Salt Lake City tore himself to touch type as in he didn't need to look at the keys while typing in 1888 murin won a highly publicized typing speed contest after which 10 finger touch typing began to catch on professional typists were soon able to achieve speeds upwards of 100 words per minute much faster than handwriting and nice and neat too so humans are pretty good with typewriters but we can't just plunk down a type wrer in front of a computer and have it type they have no fingers instead early computers adapted a special type of typewriter that was used for telegraphs called a teletype machine these were electromechanically augmented typewriters that could send and receive text over Telegraph lines pressing a letter on one teletype keyboard would cause a signal to be sent over Telegraph wires to a teletype machine on the other end which would then electromechanically type that letter this allowed two humans to type to one another over long distances basically a steampunk version of a chat room since these teletype machines already had an electronic interface they were easily adapted for computer use and teletype computer interfaces were common in the 1960s and '70s interaction was pretty straightforward users would type a command hit enter and then the computer would type back this text conversation between a user and a computer went back and forth these were called command line interfaces and they remained the most prevalent form of human computer interaction up until around the 1980s command line intera on a telet type machine looks something like this a user can type any number of possible commands let's check out a few beginning with seeing all the files in the current directory we're in for this we would type the command LS which is short for list and the computer replies with a list of the files in our current directory if we want to see what's in our secret Star Trek Discovery cast. txt file we use yet another command to display the contents in Unix we can call Cat short for concatenate we need to specify which file to display so we include that after the command called an argument if you're connected to a network with other users you can use a primitive version of a find my friends app to get more info on them with the command finger electromechanical teletype machines were the primary Computing interface for most users up until around the 1970s although computer screens first emerg in the 1950s and were used for graphics they were too expensive and low resolution for everyday use however mass production of televisions for the consumer market and general improvements in processes and memory meant that by 1970 it was economically viable to replace Electro mechanical teletype machines with screen-based equivalents but rather than build a whole new standard to interface computers with these screens Engineers simply recycled the existing Texton teletype protocol these machines used a screen which simulated endless paper it was text in and text out nothing more the protocol was identical so computers couldn't even tell if it was paper or a screen these virtual teletype or glass teletype machines became known as terminals by 1971 it was estimated in the United States there was something on the order of 70,000 electromechanical teletype machines and 70,000 screen based terminals in use screens were so much better faster and more flexible though like you could delete a mistake and it would disappear so by the end of the 1970s screens were standard you might think that command line interfaces are way too primitive to do anything interesting but even when the only interaction was through text programmers found a way to make it fun early interactive text based computer games include famous titles like zor created in 1977 players of these sorts of early games expected to engage their Limitless imaginations as they visualize the fictional world around them like what terrifying monster confronted them when it was Pitch Black and you were likely to be eaten by a grw let's go back to our command line now on a fancy screen based terminal and play just like before we can see what's in our current directory with the ls command then let's go into our games directory by using the CD command for change directory now we can use our LS command again to see what games are installed on our computer sweet we have Adventure all we have to do to run this program is type its name until this application HS or we quit it it takes over the command line what you're seeing here is actual interaction from Colossal Cave Adventure first developed by Will cther in 1976 in the game players can type in one or two word commands to move around interact with objects pick up items and so on the program acts as the narrator describing locations possible actions and the results of those actions certain ones resulted in death the original version only had 66 locations to explore but it's widely considered to be the first example of interactive fiction these text Adventure Games later became multiplayer called muds or multi-user Dungeons and they're the great forbearers of the awesome graphical MMO RPGs we enjoy today and if you want to know more about the history of these and other games we've got a whole series on it hosted by Andre Meadows command line interfaces while simple are very powerful computer programming is still very much a Written Task and as such command lines are a natural interface for this reason even today most programmers use command line interfaces as part of their work and they're also the most common way to access computers that are far away like a server in a different country if you're running Windows Mac OS or Linux your computer has a command line interface one you may have never used check it out by typing CMD in your windows search bar or search for terminal on Mac then install a copy of zorc and play on so you can see how these early advancements still have an impact on Computing today just imagine if your phone didn't have a good oldfashioned quiry keyboard it could take forever to type your Instagram captions but there's still some something missing from our discussion all the sweet sweet Graphics that's our topic for next week see you soon hey guys before we go I wanted to tell you about a new show produced by complexly and PBS digital Studios eons eons is about exploring the history of life on Earth all the way up to the most recent Ice Age and yes dinosaurs check out the link in the description and subscribe we hope you like it as much as we do crash course computer science is produced in association with PBS digital Studios at their Channel you can check out a playlist of shows like brain craft kidi and PBS infinite Series this episode was filmed at the Chad and Stacy emol studio in Indianapolis Indiana and it was made with the help of all these nice people and our wonderful Graphics team thought Cafe thanks for the random access memories I'll see you next [Music] time