86 votes
Accepted

What protocol do Teletypes use?

Aside from the character code (which I'll get to later) about the only "protocol" has to do with character framing, until very late in Teletype machines' timeline. Quick summary: The signal ...
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80 votes
Accepted

Exactly what color was the text on monochrome terminals with green-on-black and amber-on-black screens?

Based on the phosphors used for green and amber screens, this answer on Super User gives the following values: i.e. #FFB000 for dark amber, #FFCC00 for light amber, and variations around #33FF33 or #...
57 votes
Accepted

History of Ctrl-S and Ctrl-Q for flow control

Which OS was the first to use Ctrl-S and Ctrl-Q on the console for pause and continue? TL;DR; It's been developed independently of anything one might call an OS (*1). It's (nowadays) called Software ...
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  • 174k
48 votes

What is a Dumb Terminal?

Like any non-hard term, the label 'dumb' terminal is not only open to interpretation, but also used in different ways over time. Even more so for making others look bad (dumb) or one's own products ...
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  • 174k
43 votes

Exactly what color was the text on monochrome terminals with green-on-black and amber-on-black screens?

If your aim is to recreate more closely the effect of an old CRT (at the expense of readability), whatever color you choose based on the previous answer, you should consider using a very bright (...
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  • 1,478
42 votes
Accepted

How was the blinking terminal cursor invented?

The cursor is needed on a CRT raster display because otherwise it's hard to know where the next character will appear. On a teletype or teleprinter, you know where the next character will be printed ...
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  • 11.3k
39 votes
Accepted

What mid-1970s to mid-1980s home computers had their graphics characters added to Unicode 13?

The new additions mentioned are mostly to be found in the new Symbols for Legacy Computing block (PDF link) covering the 1FB00–1FBFF codepoint range. This block includes: a large number of BLOCK ...
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  • 2,591
37 votes

Were there ever any dumb terminals in a portable form factor?

if there was ever a case of a company making some sort of serial ASCII terminal, but in a portable factor Well, it all depends on the definition of dumb, portable and terminal. Let's go with the most ...
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  • 174k
34 votes
Accepted

When you type on a computer terminal, how are the characters displayed on the screen?

Terminals fall into two broad categories: Character-at-a-time Line- or Screen-at-a-time The VT100 is a character-at-a-time terminal, which means that when you press a key on the keyboard, a ...
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  • 11.3k
31 votes
Accepted

What is the difference between the "Return" and "Enter" keys in the VT100 terminal?

Under normal circumstances, there is no difference (RETURN and ENTER will send CR or CR LF as configured by the New Line Mode). However, there is a mode called "keypad application mode" ...
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  • 5,657
31 votes
Accepted

How and what did it mean to connect to ARPANET from home?

You dial in with a terminal to a TIP (Terminal Interface Processor), which then offers a simple command interface to connect you to some host machine. Living Internet web site Wikipedia Functionally, ...
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30 votes

Did terminals (e.g. VT100) require a terminal driver on the host computer?

Different terminals didn’t (and don’t) use different kernel-level drivers. In Unix-style systems, the kernel does provide some terminal-related features, called line disciplines and the TTY layer ...
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  • 96.6k
27 votes

What was the first OS with the type-ahead capability from a dumb terminal?

MS-DOS did not have a type-ahead feature, because that function was provided by the BIOS. A typical PC BIOS had a 15 or 16 character typeahead buffer, where keystrokes would be queued until something (...
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  • 5,657
26 votes
Accepted

How did early video terminals convert ASCII into font graphics?

Video Terminals I understand the term "video terminal" to refer to things like the DEC VT-100 or Lear-Siegler ADM-3A. They get characters (typically ASCII-encoded) over a serial line from ...
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24 votes

History of Ctrl-S and Ctrl-Q for flow control

First OS is hard to say. The codes go back to the 1960s with the Teletype Model 33. I have a hunch the original usage was not part of an operating system but at a lower level. In later times, ...
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23 votes
Accepted

What was the largest resolution supported by terminal escape codes?

There is no limit, at least not by definition. And more so, not something across all terminals ever made. Most prominent nowadays (*1) is the so-called ANSI sequences standard - understood by next to ...
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  • 174k
23 votes
Accepted

Emulate a text-mode DOS program using a Unix terminal

As ecm wrote, DOSEMU supports this, using -t or -dumb. This works with the original DOSEMU and DOSEMU2. -dumb runs DOS programs in “dumb” terminal mode, where output goes to DOSEMU’s standard output ...
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  • 96.6k
22 votes

How was the blinking terminal cursor invented?

In 1967, a magazine article, cited a few times in the decade afterwards, said: The cursor (entry marker) identifies the next display position to be entered. The cursor continually blinks three to ...
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  • 1,821
21 votes

Why is the serial port driver named "/dev/ttyS#"?

TL;DR: Until Unix v7, if you wanted to be able to use a serial port for terminal logins, it had to have a name starting with "/dev/tty". At the time the first Unix systems were developed, it was ...
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  • 11.3k
21 votes

What is a Dumb Terminal?

I suggest a somewhat different definition of dumb terminal. While clearly some terminals were smarter than others, I don't think things such as programmable selection of fonts and colors, direct ...
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20 votes
Accepted

Advantage of RS-232 over 20mA current loop

TL;DR: It's a classic case of technological advancement vs. installed base In the early days of electricity-based communication (i.e., telegraph and later TTY) there was no way to detect a voltage and,...
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  • 174k
19 votes

Exactly what color was the text on monochrome terminals with green-on-black and amber-on-black screens?

I dimly recall these two specific hue frequencies were picked because the human eye focuses them the most accurately. Other colors would focus in front of or behind the retina. A modern RGB green is ...
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17 votes
Accepted

How did SABRE work interactively without screens?

Wikipedia, unsurprisingly, gives incomplete information. A number of important new technologies were developed as part of the five-year R&D of SABRE, including a disk drive capable of storing ...
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  • 5,963
16 votes

Advantage of RS-232 over 20mA current loop

The current loop goes all the way back to classic telegraphy. If there's current flowing, then that's one state. If there's no current, then that's another state. It's as simple as it can be. You ...
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  • 10k
15 votes

History of Ctrl-S and Ctrl-Q for flow control

It was nothing to do with an OS as such. Ctrl-S and Ctrl-Q are simply XON and XOFF in ASCII. These codes are used in serial communications to pause and resume sending. With hardware handshake on ...
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  • 7,609
15 votes

Can anyone help identify this old terminal and printer found in an abandoned nuclear power plant?

I would have written just a comment but did not have enough rep to do so. @JdeBP had basically found the answer so all I had to google was "Youtube comment finder" :). The video also posts a ...
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  • 181
14 votes
Accepted

Why is the serial port driver named "/dev/ttyS#"?

Historically a computer terminal or modem would be the most common device connected to a serial port. Thus, the default file name for the device reflects its most common usage, similarly to /dev/lpN ...
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  • 16.4k
14 votes
Accepted

When did smart terminals arrive?

It seems to me that a smart terminal would need a microprocessor, so I would expect them to start showing up in the early seventies, Not really, as discrete, specialized processors could do the job ...
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  • 174k
14 votes

What happens when a terminal (like a VT100) is connected to a computer?

Does this mean that everything must be already set up for the user login on this port? Like a TTY driver already listening on the port, the login process already running, Exactly. In every system I'...
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14 votes

Using only one terminal, can I interrupt a process that's hung on very early Unix versions?

Yes, you should be able to interrupt a running process using the interrupt key. In Unix v6, the default interrupt key (intr) is ^?, aka DELETE, aka RUBOUT (ASCII 127). Also, the default character-...
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