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211 votes
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Why is the keyboard and cellphone / telephone numbers in a different order?

(I got the feeling I've answered this already once, but can't find it) (Also, this is meant as an overview, a timeline to see development and usage, not about any firsts, inventions or alike) TL;DR: ...
Raffzahn's user avatar
  • 226k
131 votes
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Why is Ctrl-V the Paste shortcut?

As well as being close to X and C on most keyboard layouts, “V” is reminiscent of the caret used in proofreading to indicate the insertion point for new text, e.g. text to be inserted V ...
Stephen Kitt's user avatar
125 votes
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Why wasn't ASCII designed with a contiguous alphanumeric character order?

Why is ASCII this way? First of all, there is no one best sorting order for everything. For example, should UPPER or lower case be first? Should numbers be before or after letters? Too many choices, ...
manassehkatz-Moving 2 Codidact's user avatar
88 votes
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Why does NumLock exist?

My keyboard has over a hundred keys on it. But there's one labelled "NumLock". Simply because the dedicated cursor keys were not there to begin with. As seen here with the original PC Model ...
Raffzahn's user avatar
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80 votes

Why do keyboards have an asterisk key?

Keyboards have an asterisk because typewriters did, long before computers existed. Typewriters, particularly mechanical ones, typically made a number of compromises to reduce the number of keys ...
Stephen Kitt's user avatar
74 votes
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Why do keyboards have an asterisk key?

Computer terminal keyboards needed to reproduce the symbols available on punched cards and paper tape. In the US, punched cards dominated the data-processing industry (communications uses tended to ...
dave's user avatar
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68 votes
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Why are the symbols on the number keys of PC & Mac keyboards different to ASCII keyboards?

It all dates back to typewriters, but the two layouts aren’t ASCII v. non-ASCII, they’re mechanical v. electric. The !" etc. layout was common on mechanical typewriters, based on the layout used for ...
Stephen Kitt's user avatar
64 votes

Locked-up DOS computer beeped on keypress. What mechanism caused that?

Well, it was simply the BIOS' way to tell you that the keyboard buffer is all the way filled up. What was actually "counting" my keypresses? In so far as there is a 16 entry (32 bytes) buffer area ...
Raffzahn's user avatar
  • 226k
62 votes

Why wasn't ASCII designed with a contiguous alphanumeric character order?

According to ASA X3.4-1963 Appendix A, one of the design considerations was: (7) Ease in the identification of classes of characters Furthermore: A4.4 The character set was structured to enable ...
Greg Hewgill's user avatar
  • 7,009
61 votes

Why was the return key symbol ↵ drawn differently from the motion of a CR-LF?

Even though the CR usually goes before the LF in ASCII text, most printer mechanisms actually perform the LF before, or during, the CR. So the shape of the arrow is actually accurate. This is even ...
Chromatix's user avatar
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59 votes
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How did ALT + F4 become the shortcut for closing?

AltF4 doesn’t come from Windows; it comes from IBM’s Common User Access (CUA), part of its Systems Application Architecture. This was implemented on IBM mainframes, and in OS/2 Presentation Manager ...
Stephen Kitt's user avatar
55 votes
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Why is there only one PS/2 port on my computer?

Given your computer’s vintage, I’m going to guess that the reason there’s a single PS/2 port, intended for use with a mouse, is that its keyboard port is a 5-pin DIN connector as used in the IBM PC AT ...
Stephen Kitt's user avatar
54 votes
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What do the keys on this Symbolics Space Cadet keyboard do?

The Space Cadet is a keyboard designed for use with Symbolics' Lisp Machines, and many of the extra keys are specific to that use. Starting from the bottom row: Hyper, Super, Meta and Ctrl are ...
Stephen Kitt's user avatar
54 votes
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Why did F1 become the Help Key?

While general purpose function keys are something that had already been introduced in the 60s by manufacturers like Friden (Flexowriter, 1965) or HP (9810A, 1971), it wasn't until IBM's 3270 that ...
Raffzahn's user avatar
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52 votes
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How was the clock frequency of the PS/2 keyboard protocol chosen?

Why is the clock frequency of the PS/2 keyboard protocol so high? I wouldn't call it high. It's quite in line with similar keyboard speeds - like Amiga operating a 17 kHz. At 11 bits per scancode, ...
Raffzahn's user avatar
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51 votes
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Did they forget to add the physical layout to the USB keyboard standard?

They didn’t forget to add such a function, they chose not to add one. The HID Usage Tables explain this as follows (section 10, page 88): Note: A general note on Usages and languages: Due to the ...
Stephen Kitt's user avatar
50 votes

How was the @ sign added to keyboards and character sets?

The @ symbol was present on typewriters a long time before computers were invented, see for example this 1889 Hammond typewriter. In English-writing countries, the symbol was already used in ...
Stephen Kitt's user avatar
49 votes
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Why did the C64 have ← and ↑ as dedicated keys?

The ← and ↑ symbols were originally included in ASCII-1963 as programming operators. They were used in a number of programming languages at the time, but the only common usage left today is in ...
mnem's user avatar
  • 4,555
42 votes
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Why was the return key symbol ↵ drawn differently from the motion of a CR-LF?

Chromatix' answer already perfectly nails the technical background. Especially the reference to classic typewriter mechanics, predating any TTY or terminal, where the symbol used quite closely follows ...
Raffzahn's user avatar
  • 226k
42 votes

Was there a keyboard layout starting with "TBSY"?

I've researched keyboards and character sets on two occasions (*1) and seen a lot of different layouts, from alternate roots like Blickensderfer, Sholes and Dvorak to national variants like Cyrillic ...
Raffzahn's user avatar
  • 226k
40 votes
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Why separate cursor keys?

I remember a conversation with an IBM engineer back in the 1980s, who implied there was an internal fight over this between IBM's engineering and marketing departments. The engineers wanted the PC to ...
alephzero's user avatar
  • 6,656
40 votes

How did the SysRq key get onto modern keyboards if it's rarely used?

Before IBM PC even existed, terminal keyboards for IBM Mainframes make extensive use of the SysRq or (System Request) key. I recall using SysReq key on IBM 5251 and 5291 terminals for IBM S/36. ...
roetnig's user avatar
  • 511
37 votes
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Why does PAUSE key have a long make code and no break code?

In scancode set 2, the "break" scancodes consist of the "make" scancodes prefixed by F0. This is consistent across nearly all the keys. Some keys include a modifier prefix in the Ex range as well, ...
Chromatix's user avatar
  • 16.8k
37 votes

Why are the homing bumps on D and K on Apple keyboards?

The official answer (archived here) is that they pretty much made it up as they went along: At some time in Apple's history it was decided to put the "bumps" on the D and K keys while some ...
Michael Graf's user avatar
  • 10.1k
35 votes

What was the purpose and history of the C64's special keys?

The Restore key triggered the NMI (non-maskable interrupt) line; to actually have an effect it had to be combined with Run/Stop - it would soft-reset the machine (via an indirect jump vector that ...
Joe's user avatar
  • 1,582
35 votes

Why wasn't ASCII designed with a contiguous alphanumeric character order?

man 7 ascii of Linux Programmer's Manual says, Uppercase and lowercase characters differ by just one bit and the ASCII character 2 differs from the double quote by just one bit, too. That made it ...
比尔盖子's user avatar
  • 3,114
35 votes
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Why do keyboards with a NumPad repeat the numbers?

The two sets of numbers serve different purposes, and I realise not all keyboards have the NumPad is an important factor. The main part of the keyboard is based on typewriters, and has to provide ...
Stephen Kitt's user avatar
34 votes

What's the deal with Commodore's RESTORE key?

TL;DR: There is no fundamental difference just because a different interrupt is used. For all practical purpose the Restore-key works like the Apple II's Reset-key or the PC's Ctrl-Alt-Del key ...
Raffzahn's user avatar
  • 226k
33 votes

How was the clock frequency of the PS/2 keyboard protocol chosen?

The user will perceive a delay (latency) between pressing a key and seeing the computer react. The reactions are usually on its screen, such as displaying a typed character or motion in a game. This ...
TonyM's user avatar
  • 4,268
33 votes
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Did any MS-DOS program ever use the System Request interrupt?

TL;DR: One of the great Ideas that never Materialized Contrary to what is often assumed, the key was not added to support some 3270-style emulation1, but to enable a basic multi-application/OS ...
Raffzahn's user avatar
  • 226k

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