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A Brief History of Modems

Ant points out this two-page TechRadar article about the history of modems; the photographs of some behemoth old modems might give you new respect for just how much is packed into modern wireless devices.

5 of 249 comments (clear)

  1. Acoustic coupler era and POTS! by arth1 · · Score: 5, Informative

    There are still a few of us left who grew up in the acoustic coupler era, where modems connected to the (back then standardized) handset, and really whistled and purred into the microphone.
    Speeds? We started with 110 baud (which back then was equivalent to bits-per-second, if you subtracted stop bits). Then came 300 baud.
    Then someone had an epiphany, and figured out that no-one could possibly type faster than 75 characters per second, and even if they could, the printer(!) that spit out whatever you typed wouldn't be able to. So by reserving the low frequencies for upstream data and the high frequencies for downstream, you could achieve the blazing speed of 1200 baud down and 75 baud up. The 1200/75 modem was a workhorse for a long time, with way faster downloads than 300/300 could give.
    Then came 1200/1200, 2400/2400, 4800 (which was really 2400 with compression), 9600, and then the Trailblazer, which was running at a ridiculously low baud rate (100 baud IIRC), but at so many parallel channels that it achieved ~18000 bps aggregate. That was lightning fast! Imagine almost 2 kB/s (unless something moved the other way at the same time, in which case speeds of course would drop). The ASCII porn didn't stand a chance against that speed monster!
    Then came the short-lived 38400, and finally the ubiquitous 56k modem. Yawn.

    In the mid-90s, we got BRI (ISDN, 2*64 kbps in most of the world, 2*56 kbps in the US). Which pretty much ended the modem era, except for in the US and UK, where 56 kbps POTS modems reigned supreme until well after the millennium.

    1. Re:Acoustic coupler era and POTS! by arth1 · · Score: 4, Informative

      No, in the US T1 system, each B channel is 56 kbps, due to the entire T1 using inband signalling through bit-robbing (see above referenced article), and not out-of-band signalling as in the E1 system used elsewhere. At least that was the case back when ISDN became popular in the early-to-mid 90s.
      The 16 kbps data channel for each B pair is independent of this.

      T1 PRI = 23 * 56 kbps DS0 (+ 16 kbps), US BRI = 2 * 56 kbps (+ 16 kbps)
      E1 PRI = 23 * 64 kbps DS0 (+ 16 kbps), EU BRI = 2 * 64 kbps (+ 16 kbps)

  2. As a child of the 80s... by HockeyPuck · · Score: 4, Informative

    The biggest problem with using modems was that you had to let everyone in the house know you were on the "modem". This meant, sticking post-it notes to every phone in the house, so that someone would tell you they needed to use the phone rather than just picking up the phone and dialing. You also couldn't tie up the phone for hours on end. There was very very few people that had an answering service (not an answering machine), like most do today with VOIP or CableCompany Provided Voice.

    You also had to remember, if you were one of those people that had it, disable call waiting, as many modems would drop the connection when a call waiting signal came through. I believe you had to add a *70 after the AT.. so you had something like:

    AT
    OK
    AT&F
    OK
    ATDT*70,,,867-5309
     
    RING.

    Today people can spend all day actively or passively (by leaving the computer on) online. Wit

  3. Re:Baud vs bps by aberkvam · · Score: 4, Informative

    The American Heritage Dictionary of the English Language, Fourth Edition says, "acronym n. A word formed from the initial letters of a name, such as WAC for Women's Army Corps, or by combining initial letters or parts of a series of words, such as radar for radio detecting and ranging."

    MOdulation/DEModulation certainly seems like it qualifies to me. It is using the initial parts of a series of words. I don't see how it is any different than RAdio Detecting And Ranging.

  4. Re:Let me be the first to say by adolf · · Score: 4, Informative

    You mean:

    +++
    [pause*]
    ATH0
    ATDT18400MODITUP

    [*: Pause required for modems properly requiring a delay before dropping to data mode, as patented by Hayes. Other, non-supporting/paying modems used the same commands, but did not require silence between +++ and a command: A properly-crafted ping command was sufficient to take such modems/users completely neatly offline in an age of TCP/IP, though a link for a citation evades me in these modern times.]