84

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 from a sending teletype to a receiving one is a single line, usually a current loop (two wires), which is always in either "marking" (current flowing) ...


73

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 #66FF66 for green. Additionally, colours vary with brightness adjustments and with the age of the phosphors. It should be pointed out that reproduction of ...


56

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 Flow Control and has been around since the early days of computers using ASCII I/O, as the Model 33 Teletype used the device control codes DC1/DC3 (CTRL-Q/CTRL-...


41

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 because that's where the print head is positioned. The full-block cursor depends on the ability of your video hardware to do reverse video (otherwise the ...


41

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 (almost white) color for the text itself, and then using the chosen color as a glowing neon-like effect around the outline of the text. For example, here is what you ...


39

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 SEXTANT characters like 🬥 BLOCK SEXTANT-1236 ("The term 'sextant' refers to block mosaics divided into six parts." Also note because these definitions are new, ...


30

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 character gets sent to the computer. If you have "local echo" enabled, then as soon as the character is sent it is also immediately displayed (often done using a ...


30

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, this is no different from late 20th-century terminal servers. The terminal connects to a device (a small dedicated computer, network attached) which implements (...


29

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 which you mention; there is typically at least a raw line discipline (which doesn’t perform any translation), and a cooked line discipline (which provides more-or-...


26

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" where all the keys on the numeric keypad send their own distinct control sequences which are different from the rest of the keyboard. From the VT-100 User Guide: ...


24

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, certainly by the 1980s, there were plenty of devices that functioned with software flow control at the hardware level. Microcomputer operating systems that supported ...


23

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 all terminals built after ~1978. Trying to be as device agnostic as possible, it implies no upper limits by itself. The structure is built (*2) around an ...


23

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 and can thus be scrolled back in your terminal or redirected. -t uses S-Lang to provide an emulation of a PC text-mode screen inside the terminal, with colours, ...


22

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 five times per second, which permits quick visual location by the operator. — F. H. Reagan Jr. (February 1967). "Viewing the CRT Display Terminals". Data ...


21

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 common to use a Teletype as a terminal. Early models of the DEC PDP-11 computer came with a Teletype intended to be used as the console terminal. "tty" is an ...


19

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 pretty close to the right color of green, I believe so can be used as is. Recreating the old amber on an RGB screen does not work because it generates not a ...


19

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, when needed, amplify it. Only current flowing in a closed circuit could be detected reliably—by having it run through a coil which in turn moved a lever—and ...


17

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 that many reservations, a new transaction-processing system, a frequency-modulation system to send data over the phone lines, and a new model of terminal, pictured ...


16

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 don't need to manipulate voltages. That's the key. Just turn a literal switch on and off. It also has problems. Current losses are heavy even in short ...


15

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 RS232 and similar communications standards used the RTS (RequestTo Send) & CTS (Clear To Send) handshake lines. Many comms links were, and still are, three ...


14

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 for parallel ports, where "lp" stands for "line printer". For convenience, the device files corresponding to the (sub)set of serial lines dedicated to user ...


14

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 even before that. When did they arrive on the scene? TL;DR: Gradually between 1964 and 1971 As with every 'first' question, the answer is rather vague and ...


14

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've worked with, a port is assigned at or before boot time to be a terminal (input/output TTY-style session), printer, modem (as an auxiliary port - if it is for ...


14

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-erase key (erase) is #, and the default line-erase key (kill) is @. You can use stty to change the 'erase' and 'kill' keys but v6 stty doesn't let you change the ...


13

Each terminal gets its own set of processes: first getty, which sets the terminal link up and waits for a login, then replaces itself with login to handle the actual login, and finally login runs the user’s shell. So yes, each terminal gets its own shell (once a user has logged in). This doesn’t happen automatically, it’s set up by init which uses the ...


13

Per this site about using one with Linux: it's a current loop — i.e. presence or absence of current indicates high or low level; it can be cheaply interfaced to RS232; the host will need to speak Baudot code, as per pndc's answer that predates this one; code entries should be transmitted and received with one start bit and two stop bits, no parity (so, 5N2);...


12

Why it has been designed, where it has been used? Its target market was terminals. The 8275 is a very versatile logic chip for generating text displays (*1) so nearly any terminal format of that time, with up to 80 characters and whatever attributes needed, can be handled. It was made to cover the full range from simple 32x20 with 8x8 cells all the way to ...


12

I don't have any experience with the exact modification you are talking about. However, I think it is a relevant point that the design of the firmware for Commodore microcomputers included a "screen editor" as a separate bit of software from the BASIC interpreter. As far as I know, all the CBM 8-bit machines had this design. So, it is very possible ...


11

Apologies for a non-definitive answer; while implementing a CP/M emulator for the Mac I find a fairly even split in the terminals that software available via Walnut Creek, etc, was configured for out of the box between the ADM-3a, VT-52, Hazeltine 1500 and Osborne control sets. If you're looking to do a really thorough job, I found that simple statistical ...


11

This information is based on information from the DEC VT220 Technical Manual. I've not actually tried this out myself, but it did work for the OP when he tried it. TLDR: Yes, it's likely to work, and quite cheap to try using a sub-$1 BNC to RCA adapter if you already have an RCA-RCA video cable. Section 1.4 says that the "BNC connector for composite video ...


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