I would like to understand the stories of the internet, but each source says something completely different. I know that ARPANET was going to connect computers at different universities with each other so that they could share their computing power better, because they were "big, bulky, slow and difficult to program". There is also a theory that says that it was about the exchange of research results, and supposedly not true - the desire to create a network resistant to nuclear attacks. The story of the first message "LO" was sent suggests that terminals, not mainframes, were connected by telephone cables. Others claim that they were not used then. So what was it like from the scientists' perspective? How and why were these first local networks with terninals created and how did they develop in networks connecting long distances?

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    Terminals connected people to the mainframe. The network connected mainframes together. You need a terminal as a human to interact with the computer and by extension the network.
    – Jon Custer
    Aug 26, 2022 at 13:22
  • This is a "physicalist" question :-) I generally look on networks as connecting programs. There's a serious point in this silly comment, somewhere - the hardware network connects computers, which then allows you to connect programs, which then allows you to build a remote-login sort of program to connect a terminal to a remote computer.
    – dave
    Aug 28, 2022 at 14:40

1 Answer 1


Strictly speaking, ARPANET connected IMPs (Interface Message Processors), or similar pieces of equipment, but people thought of it as connecting mainframes or minicomputers and that’s what appears on logical maps of the ARPANET: the nodes shown on the maps are SDS machines, PDP machines, CDC machines, 360 systems etc.

As far as users were concerned, ARPANET was fairly similar to text-oriented Internet. The first application (and protocol) available was Telnet (for remote shell access), followed by FTP (for file transfer) and email. There was even an early attempt at voice-conferencing but that never worked well.

Terminals were (and still can be) used to connect to mainframes (or any computer capable of driving a terminal, including microcomputers), either locally or over phone lines; but the connection between terminals and their mainframe didn’t involve ARPANET. You’d use a terminal to interact with a computer, whether or not that computer was connected to a network; and if that computer was on the ARPANET you could connect from there to another computer.

(There are other, later, networks which are used to connect terminals to computers, such as X.25-based networks, as famously used for the French Minitel; but that’s not the model ARPANET followed.)

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    I'd say the last paragraph is maybe about the most important misconception here: Terminals are not connected to the net, but always to some active component - either a generic computer (mainframe) or some specialized linke a terminal controller, which then is connected to any net. Otherwise they are not terminals, but active components (computers) themself. That's independent from whatever network is used.
    – Raffzahn
    Aug 26, 2022 at 13:39
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    Though the TIP muddies those waters somewhat, especially if the TIP was coresident in the IMP.
    – dave
    Aug 27, 2022 at 0:43
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    In US, Tymnet and Telenet (note third e) were contemporaneous, but not related to ARPAnet Aug 27, 2022 at 2:47
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    As an embedded developer, I will just add that the serial terminal is very much not dead, although nowadays it's an emulated one on a PC. I use it regularly when working with various embedded devices.
    – jaskij
    Aug 27, 2022 at 12:52
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    @StephenKitt - but even the -10 was not called a "mainframe" by its users, despite being a large-ish computer. The term generally meant systens playing in the same "data processing" market as IBM (the "seven dwarves"), though of course universities had IBM mainframes too.
    – dave
    Aug 28, 2022 at 14:31

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