119
Much of this has been covered by previous answers, but to try to summarize:
Adding a speaker was cheap and easy. The additional parts were standard, reliable, and inexpensive.
It provided rich, immediate, understandable feedback on a variety of call-progress milestones.
Click -- modem is responding enough to grab the line. (This click was usually from a ...
98
Up to 9,600 baud it's just iterative application of fairly straightforward analogue-domain ideas as and when standards emerge. Then there's a significant improvement on the digital side that bumps to 14,400 baud. Incremental phone line improvements lead from there to 33,600 baud. Finally, a digital back end for the phone network provides 56k as a downward ...
63
Not all modems from back in the day had speakers, for example an early popular modem was the Hayes Micromodem II (available for Apple ][ and S-100 machines) and it did not have a speaker.
But the speaker served a few purposes that I can think of:
Early modems were not very good at detecting various states, e.g. busy line, voice pickup, disconnected number ...
32
So why were modem speakers such a persistent feature, and "fixture" of the time?
Three basic reasons:
Adding a simple amplifier and a speaker is the most easy way to handle unexpected situations
In many countries/networks having a speaker active while establishing a connection was mandatory to make it legal/get a validation
Adding it was as well the least ...
31
It appears to be a legacy from TOPS-10. The easy part: octal was more popular in the 60s and 70s in general, but especially at DEC, which produced a number of 18-bit machines; the 3 bits per symbol divides 18 bits evenly, but the 4 bits per symbol of hex doesn't.
CompuServe's beginnings weren't as a bulletin board or ISP, but as a general-purpose ...
24
A/the correct solution would be to set up some sort of small local PBX. In the spirit of retro you can probably score an analogue PBX for not very much money and the mechanical ones are arguably even more fun to play with than retrocomputers because you can watch them working, but if you would like that bit to be somewhat smaller and more reliable than a ...
22
Many games played over the Internet today use a client-server model, where the server has a full copy of the game state, and distributes appropriate pieces to the connected clients. Due to the technology available in 1994, XBAND couldn't work this way.
When the user wanted to play a game online, the modem called the server through a local dial-up point-of-...
22
Fax machines use distinct frequency ranges for upstream and downstream transmission, with one direction receiving the vast majority of the bandwidth. Computer modems at 9600 and higher baud rates used he same frequency ranges for both directions, supporting high speed transmission in both directions simultaneously. This made it necessary to use a more ...
21
I'll add a detail to the topmost answer.
Data modems up to 2400bps used different frequency bands for transmit and receive. But why?
Look at your telephone wire. There are only two wires going between the modem and the wall, yet you must transmit and receive over the same wires. With a telephone, some of the speaker's voice gets redirected to the earpiece, ...
19
It sounds like what you're looking for is Telenet (renamed to "Sprintnet" when Sprint acquired it) or Tymnet.
Tymnet did not survive and Sprintnet became part of what we now know as the Internet.
19
300 bits per second has the advantage that it is the lowest common multiple of both 50 and 60. These made it easier to use the power line frequency (50 Hz in Europe, 60 Hz in USA) to synchronise the bit timing circuits. This was long before Quartz locked circuits became cheap enough to include in teletype equipment.
18
Short answer:
Because it was useless to begin with.
For a more detailed answer the whole picture is needed:
Back in the real old days modems were symmetrical. A V.21 modem split the line into two 300 bps channel, one for each direction. So single direction transfer would use only a half the available bandwidth. This stayed true including the 2400 bps ...
15
10 CPS/110 Baud was the maximum rate these signals could be sent with acceptable sidebands using an all-mechanical system. 300 was 3 times the teletype speed, and that limit is set by the 4 kHz maximum bandwidth of a phone line and the allowable harmonics.
300 baud is exactly 3 times 110 Baud, measured in characters. The teletype standard was 110 bps ...
15
A very good first answer however I would also like to note that any data rates above 300bps could not be acoustically coupled and were direct connect modems only. And anything 33.6K and above basically demands at least one digital endpoint. By that I mean that the modem access concentrator would connect to the Public Switched Telephone Network via data-...
11
I suspect it could be a holdover from the days when a modem was a box that connected between your terminal and your phone. The phone handset was used to dial the remote number; when you heard the whistle from the far modem, you'd press the 'online' button on the modem, and then replace the phone handset.
And, of course, if it wasn't a modem whistle you ...
10
All the answers above have concentrated on outgoing calls but modems also took incoming calls and, because phone lines were expensive, it was unusual to have multiple lines for fax, data, and voice.
Therefore the modem was usually installed in-line with the phone (i.e. the circuit came into the modem, and then continued onward to the handset).
Usually a ...
9
I thought the RS-232 port on the Vic-20 was completely separate from the cartridge port, so a thing had to be plugged into one or the other, and if the modem was plugged into the latter then it could not use the former. What am I missing?
Or better what is mixed up. The device (Serial IEC) bus is often called a serial port, but that one was driven by VIA#2 ...
9
"Null modem cable" may not quite be a misnomer but is potentially misleading: it is a cable that connects two computers via their serial ports without modems. It's not a null cable for modems, it's the null example of one of those cables you use to connect a computer to a modem.
So if you want to make it look like there's a phone network between two modems ...
9
By the time I got my first analog modem, around 1980, my experience was the same as yours. Even and odd parity on 7-bit data was available, but almost all the BBSs featured 8N1. (The modems even still supported 5- and 6-bit data streams.) Apparently noise on phone lines by that time was so low that parity detection was considered superfluous for a large ...
7
Parity is a "one-bit checksum over a single character". It can be used to detect single-bit errors in a serial asynchronous link (As the checksum is only one bit, two or more bits/char failed transmission can go undetected).
Parity "even" adds a bit so that the sum of all data bits in the byte frame is even, while "odd" parity does the same so that the sum ...
7
I would say the big breakthrough is when V.90 was introduced. ISPs no longer had traditional modems installed to receive calls as the analog phone lines were replaced with 64kbit digital lines or multiplexed over T1 and similar.
This removed the digital to analog conversion that was done on the ISP side, allowing up to 56kbps from the ISP to the customer.
...
7
I think the primary driver was the new availability of the Internet in the home. At that time modems were the primary method of getting online so it was worthwhile for companies to pursue ways to make modems faster. They implemented compression and better ways to encode the data so more bits could be transferred per second. They also focused more on ...
7
CompuServe was initially a Time-sharing system utilizing original DEC PDP-10 machines. You would log in as a regular system user and run your programs. The credentials of these systems consisted of two octal numbers, the Project Number (1-377777, 1–10 reserved — akin to groups in Unix systems as I understand it) and the Programmer Number (1-777777, 1–7 ...
7
Simply because DEC used octal representation of binary values, where IBM (and later micros) used hex. The PDP-10 used an 18 bit address and half word as smalest computational unit (the machine had 36 bit words). 18 Bits can be represented as 6 octal digits. So here you are. They just followed that scheme.
7
I don't think it is likely that there will be published numbers showing the relative usage of different modem connection speeds over any large population of users. The best we can provide is some historical perspective on the timeframe for transition from 300 baud to higher speeds.
In general, 1200 baud modems enjoyed a fairly brief popularity because they ...
7
Why were these specific frequencies chosen other than needing to fit into the voice band
Erm, in the end it's all about fitting in the voice band of 300..3400 Hz.
For one, 1 kHz and 2 kHz are almost equally spaced within the voice band, having the maximum distance between each and its boundaries, giving optimal placement and separation.
Next, 200 Hz between ...
6
You're looking for the Telebit QBlazer.
It wasn't just 19.2k, but a 9.6k V32 or 14.4k V32bis as QBlazer+. Your confusion might originate in their claims to run up to 38.4k ... available due to compression.
It also was more like 2.3 inch (6cm) on each side. But yeah, small and portable and still a full figured desktop modem. The ability to be powered from a ...
6
(Caveat, this is from memory)
After connection to the remote modem, Microcom modems played a special tone into the line and listened for a response; if a proper tone was received in reply, the modems entered their error-correcting state.
Completely and utterly rubbish. There was no special tone. It was a bunch of characters, some of them encoded in ...
5
The answer might be too simple and not as desired: Nothing revolutionary or new in particular.
The underlaying physics/mathematics and the technology neccessary was know since quite some time. Speed up was mainly driven thru general availability of faster chips and classic market forces: Fast enough DSP and lowered prices within an emerging mass market.
...
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