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25

That's how the shift key sometimes worked on old terminals and ASCII is designed around it. But on a modern keyboard, the SHIFT key just does exactly the same as every other key on the keyboard: it sends a 'key down' signal and a 'key up' signal. This doesn't affect any other signalling and the computer it is connected to determines the net effect.


21

The "PETSCII" encoding is based on keyboard positions of the original PET chicklet keyboard (*1): (Taken from Wikipedia) The keyboard is made similar to basic typewriter keyboards, but ordered in a square fashion, including a top row of symbols but not numbers and a separate numeric keyboard. By every key holding only a single ASCII equivalent ...


19

IBM started using ASCII before 1970; the 2260 terminal, released in 1964, used the unpublished (but ratified) 1965 version of the ASA X3.4 standard. IBM mainframes still use EBCDIC, so I don’t think their popularity had much bearing on the popularity of ASCII (but other encodings’ popularity influenced IBM mainframes: their instruction set includes ...


19

TL;DR: ASCII was never intended for processing, just as an interface standard for data exchange (hence the name American Standard Code for Information Interchange) IBM never switched, it still uses EBCDIC within mainframes and ASCII for communication. IBM was a major proponent for ASCII, but not the sole force, and especially not international. ASCII soared ...


9

I think the codes were laid out so that when laid out sensibly on the PET keyboard, the shifted and unshifted forms of each key would have a consistent relationship. When the VIC-20 reduced the number of keys but added the Commodore key, this made it necessary to rearrange the placement of graphics on the keys; since Commodore kept the same arrangement of ...


7

From a pure hardware point of view, a significant amount of computers keyboards see each keypress as a bit set in a matrix of rows & columns, so with another operating system you could theorically map "shift" to another key. So one could say that only the operating system makes the shift/control/alt keys different from others. However there are some ...


7

I believe the only way we can answer this question is by members finding 'the earliest' such description. DEC's first CRT terminal device, the DEC VT05 terminal (1970), had tab stops fixed at 8-character intervals. The DEC VT50/VT52 terminals (1974) had tab stops fixed at 8-character intervals. The DEC VT100 terminal, (1978) which replaced the VT52, had tab ...


4

For what it's worth, I did a quick photo of my C-64 and VIC-20 keyboards, so it's very easy to see the physical grouping of the various graphics/symbols. Commodore C-64 Keyboard: Commodore VIC-20 Keyboard:


4

In the 1960s, IBM used a crazy variety of character codes. IBM was the king of punched cards, commonly known as "IBM cards", so many codes related to the sparse 12 bit codes used for those. However, even these were not fully standardized: different keypunch models used different character sets! 6-bit BCDIC was designed to easily map to the most ...


3

Modifier keys were sometimes wired differently than other keys. How to make a keyboard with 100 keys. You can use a microcontroller with 100 inputs and eack switch connected on one side to the power supply and the other side to the microcontroller. Simple, but that's a lot of signals, fairly expensive. You can arrange keys in a 10x10 matrix. The ...


3

I posit that the original use of control characters was strictly for non-textual usage. In other words, things that don't print. In ye olden times, that was the primary way to communicate anything other than actual text to: Terminals - initially printing, e.g., ASR-33, and later video terminals, e.g., ADM-3A, VT-100, etc. Printers Modems - to control the ...


2

One example of the classic ASCII control codes being used today would be ETX and EOF. On a Unix-like system in the terminal, Ctrl-C is ETX and will normally quit the program, and ctrl-D is EOF and is often used to mark end of input to a program.


2

Answering one of your questions "When did ASCII become a worldwide standard", the answer is: never. The "A" stands for "American". At the time the US adopted ASCII, other countries were adopting their own variants, substituting different characters according to national needs: for example in the UK, "£" was substituted ...


2

I'm going to provide a terrible answer, but include a couple references that might be great for nostalgia. One is NostalgiaNerd on youtube, he provides a British viewpoint of IBM's shift to ASCII (OK they only did it through codepages, not really fully/completely ASCII). The video is strangely titled, nothing about ASCII or EBCDIC in the name: "These ...


2

Is 1949 early enough? The Manchester Mark 1 had 20-bit wide instructions which were conventionally written as four 5-bit characters using a variation on teleprinter code which Alan Turing adapted for the purpose by replacing control codes with printable characters so that all instructions and data could be written as text. One might suggest this is cheating ...


2

This certainly seems to be possible on the 6502. While several seemingly crucial instructions (like STA, STX and STY) exist only with the 8th bit set, it's still possible to construct arbitrary bytes in RAM using SEC with the read-modify-write forms of ROL, ROR and/or LSR, provided the RAM addresses are printable ASCII. The full set of ADC/EOR/AND opcodes ...


2

The first example of an ASCII executable you saw is in the Google Usenet archive here


1

I got a little carried away researching for what was just intended to be a mild elaboration on what was already said. I hope you find this interesting nonetheless: Old Terminal Hardware First, the ASCII section in Eric S. Raymond's "Things Every Hacker Once Knew" goes into more detail on how old terminals mapped keys, including that Shift toggles the 16 or ...


1

The data output by keyboards varies with different computer systems and protocols. While your theory is certainly plausible, a typical keyboard outputs "scan codes", rather than ASCII codes - typically over a serial interface. While modern PCs use USB as the physical interface, with the USB HID protocol running on top of that, the protocol dates back to the ...


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