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28

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: ...


22

It's a little cheaper to build all-in-one units because you only need one cabinet and one power supply, and you need fewer cables and connectors and supporting electronics. And back then, people didn't often have monitors that they could reuse on new computers, just televisions which often had only RF inputs and couldn't produce a sharp image for text. So ...


13

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 ...


11

This was not done by a “driver” at the OS level as you are thinking of it. In Unix, there were drivers that dealt with the RS232 interface and these were surfaced as /dev/tty* devices and dealt with things like speed, echo, etc. As for escape sequences controlling the display of the terminal, that is not done at the “driver” level as you are thinking of it....


9

"It depends". I'm answering this in the context of DEC timesharing systems, since that's the natural habitat of a DEC VT100. There's a hardware device such as a DZ11 terminal multiplexer (8 lines) that controls terminal lines by some physical protocol, such as RS232 or 20mA current loop. The physical protocol is a matter for the hardware. But the OS needs ...


8

The short answer is yes. You can change the baud rate of a VT100 talking to a PDP-11. On the VT100, this is simply done using the Set Up facility. This is entered using the Set Up key on the top left of the VT100 keyboard. This takes the VT100 offline and into a configuration mode. Then press 5 to take you to a screen where you can change the baud rate ...


6

Most of the problems that you list were simply not considerations in the mid-70's. The Commodore PET was not hard to lift safely. Its monitor (in the 40 column variety at least) was tiny and didn't contribute as much to the machine's weight as the vast quantities of sheet steel used in the construction of the case. And don't forget that it was a novelty ...


6

Well, as usual with complex matter the answer is a mixture of Yes/If. First of all, are these assumptions correct? Yes, the assumptions stated are perfect good and correct. In general. In detail there can be diversions, most depending on line characteristics (like blocking and error correcting modems), and ways the computer/its OS is designed. Now, my ...


5

If the line is using modems, then the modem knows when you've called it (carrier detect), and after some handshaking, signals the host OS that the line is now connected. Alternatively, for hardwired terminals, the line is 'always connected'. In late 20th-century usage, the host end would 'autobaud' to detect the terminal speed, which typically required you ...


5

First of, this question is impossible to be answered in a general context, so the assumption of a Unix(oid) system will prevail. Second, even in a Unix(oid) environment variations are way too large for an exhaustive answer. 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 ...


5

Two more slightly different situations from the past (well, everything in Retrocomputing is from the past...): 3270 Emulation When I was at the University of Maryland, College Park in the early 1980s, there were some Vaxes, a Univac 1100/80 and some other non-IBM large systems, and there were some micros (my first networking course was on the then brand ...


4

The approach I remember liking on some terminals of that era that I liked (not sure if I noticed DEC ones doing this, or some other company's) was that there were four intensity levels (including off). Normal text was 2/3 intensity. Inverse text was black on a 1/3 intensity background. Highlighted was full intensity. Highlighted reverse was 2/3 intensity ...


4

I guess that's a field one can come up with many views - and all presented answers so far give a valid view with lots of additional information. This is intended to break it down to a more general statements: No, at the core no OS offers terminal drivers. Just serial (or whatever) line drivers handling bare communication to a device connected. Input (and ...


3

The DEC VT100 itself did not have a driver. When you connect a terminal like a VT100 to a serial port it was a just tty device. VAX/VMS used a utility to configure devices for the operating system. As a Field Engineer, I had to run the utility after adding a new controller like serial line multiplexer to a VAX system or MicroVAX. This was followed by ...


3

We have to distinguish between different cases, but in most cases the answer seems to be "no": In "early" systems (like the Altair 680 in home computing or 1960s professional computers) programs simply wrote bytes to the serial port and they read bytes from there. In fact, such machines often did not even have an operating system. If you used VT-100 (as ...


3

Indeed, the PET likely took a lot of design ideas from "dumb" (actually semi-intelligent - very few of these weren't simple microcomputers inside!) terminals of the 70s, and kept the non-detachable keyboard. It was how a commercial computer workspace was expected to look like in that era. Where did the dumb terminal makers get the dumb idea? Electric ...


2

If the DTE and DCE are physically connected (i.e. a serial cable between them) and those endpoints support changing speeds then the speeds can definitely be changed mid-stream. The example would be two terminals on either side of a null modem. If the terminals both reconfigured from, say, 9600 baud to 19.2k the session would continue (..possibly with some ...


2

Three other reasons are conserving space, design aesthetics, and portability. The original Macintosh was an example of how to use the form factor for portability, you could get a fabric carrying case to hold your mac + keyboard, and take it back and forth between locations. I actually did this, it was probably at the weight limit for easy portability back ...


2

Short answer is yes. https://www.pcjs.org/devices/pc8080/machine/vt100/ has a vt100 emulator. Once you've selected the "emulator" screen press: F9 - Enter setup 4 - Toggle local/online to local (check the "LED" at the top) F9 - Leave setup to change into local echo mode, then type away....


2

The TTY port must be set up to handle the terminal otherwise it will not respond. It does not normally detect the connection of a terminal. When you connect or power on a terminal to a RS232 port you normally have to send a CR or two to get the login: prompt. However, if your terminal is connected and powered up when the system boots you will see the login ...


2

Back in the day I always added the DCL command "$Set Term/Inquire" to my login.com script to let VAX/VMS figure out the type of terminal I was using. I find it interesting that it seems at least once a week, I see references to DEC's VT100/VT101 in modern software. I remember having a directory full of animated txt files and some txt files to make a Dectalk ...


2

It depends. There were several different things done over the ages. Some system had automatic baud rate detection. Here the port adjusted itself to the baud rate of the terminal. After hitting some keys several times (such as Carriage Return), the port detected the sequence and adjusted itself until it cleanly got the right key. On my systems back in ...


1

RS232 is a very simple protocol. In most basic form it just sends character data back and forth and there's very little more over that. Think of VT100 as a keyboard + monitor pair. You can unplug your monitor and keyboard from a running PC after you've logged in, then someone comes and plugs their own in... and they are logged into your account, because the ...


1

Originally, the escape character was used to initiate multi-character sequences when it was necessary to support more functions than could be accommodated in 31 active control characters (codes 0x00 and 0x7F were reserved as padding characters that would be ignored). Because some usages would require transmitting that character a lot, a key for transmitting ...


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