Ctrl-Alt-Del


Anyone that’s ever used a PC will know about Ctrl-Alt-Del. Well. At least they’ll know it’s a seemingly random selection of keys that you press to make the computer do something. But why? To answer this, we’ve got to go back into the mists of time – the mid 70’s to be precise. Computer use was restricted to large corporations, the military and universities.  Computers really weren’t recognisable by today’s standards being much larger and massively more expensive. They were pretty limited in what they could do too, and the Internet was something largely limited to the military and the largest education establishments.

 

In the mid 70’s a new type of “personal computer” started to appear. Whilst still costing thousands, they were squarely aimed at small companies and individuals. A number of companies competed to bring their own variety of computer to market with varying degrees of success. In those times, it was rare that one variety of machine would be compatible with another. Then in 1981, along came the IBM PC. How this came about is an article in itself but one of the interesting things that IBM did was to make significant use of existing technology – why spend money designing something when you could buy it in? This included software and significantly Microsoft were the company chosen to provide the operating system known as PC-DOS. Microsoft were allowed to sell their own version of this and so as the market in PC “clones” gathered pace,  PC-DOS (known as MS-DOS when not on an IBM PC) was starting to appear everywhere.

 

So take a step back to the design of the IBM PC. The software designers needed a way to restart the computer – mainly for test and development purposes. Certainly not something envisaged for general use but a quick way of restarting that the early developers could use. This quick way of restarting had to be something that you couldn’t do by accident and ctrl-alt-del was chosen. Simply because you couldn’t press this accidentally and you needed to use both hands. One of the key reasons the IBM PC became so popular where other designs had failed was because the design specification was published. In the technical documentation available to the general public, Ctrl-Alt-Del was documented. It was only ever intended to be an internal development feature but because of this, it became widely known.

 

So for the first few years of the PC’s existence it became widely known that pressing ctrl-alt-del would restart the computer. Fast forward to the development of Microsoft Windows and the team developing the software needed a way to allow users to logon that couldn’t be faked (the risk of malicious software automatically logging was not something they wanted to happen) and hence Ctrl-Alt-Del was chosen. As an aside, it’s reported that Bill Gates, then head of Microsoft wanted to add a single new “logon” key to the keyboard layout but IBM wouldn’t alter their design. I’m not sure about this when you review the possibility of hitting this key by accident.

 

 So in summary, it’s a development feature used when the PC was first designed that no one would have known about were it not for a thorough documentation team including it in technical documentation. The underlying design of the PC is still fundamentally the same as it was in 1981 and so Ctrl0-Alt-Del lives on.

 

 

Refs: – https://en.wikipedia.org/wiki/Control-Alt-Delete

http://www.theverge.com/2013/9/26/4772680/bill-gates-admits-ctrl-alt-del-was-a-mistake

http://lowendmac.com/2006/origin-of-the-ibm-pc/

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