[Coco] Coco Modem phone line connection

[Dave Philipsen]

The telephones themselves do not but in many cases the telephone system 
to which the phones are connected uses a form of multiplexing in order 
to carry more conversations on fewer lines.

Dave


On 12/1/2019 11:35 AM, Alex Evans wrote:
> Phones don't use time division multiplexing, and neither do classic
> analog modems. If we look at the simple case of a 300 baud modem, it
> manages full duplex because it uses four different tones, two for the
> answer side and two for the originate side with one tone one each side
> for 0 and a different one for each side for a 1. Originate uses 1070
> and 1270 Hz while answer uses 2025 and 2225 Hz. You could call it
> frequency division multiplexing.
>
> On Sun, Dec 1, 2019 at 9:42 AM Dave Philipsen <dave at davebiz.com> wrote:
>> Actually you can talk full duplex on two telephones by simply connecting
>> them both to the same relatively high impedance power supply. I think
>> time division multiplexing is what allows multiple signals
>> (conversations) to share the same path or pair of wires.
>>
>> Dave
>>
>>
>> On 11/30/2019 8:43 PM, Joel Rees wrote:
>>> Time multiplexing, as I understand it.
>>>
>>>
>>> 2019年11月20日(水) 13:39 Dave Philipsen <dave at davebiz.com>:
>>>
>>>> Yes, in much the same way in which one line allows you to both speak and
>>>> listen at the same time (full duplex) using a standard voice telephone.
>>>>
>>>> Dave
>>>>
>>>>> On Nov 19, 2019, at 10:43 AM, rietveld rietveld <rietveldh at hotmail.com>
>>>> wrote:
>>>>> Does one line do both receive and send of the data?
>>>>>
>>>>> Sent from my BlackBerry
>>>>>    Original Message
>>>>> From: Gene Heskett
>>>>> Sent: Tuesday, November 19, 2019 11:25 AM
>>>>> To: coco at maltedmedia.com
>>>>> Reply To: CoCoList for Color Computer Enthusiasts
>>>>> Subject: Re: [Coco] Coco Modem phone line connection
>>>>>
>>>>>
>>>>>> On Tuesday 19 November 2019 11:17:10 rietveld rietveld wrote:
>>>>>>
>>>>>> It looks like the coco only uses the middle two wires(red and green)
>>>>>> on a four line phone cord.   Is this correct?
>>>>>>
>>>>> Probably, since thats all it takes to run a telephone.
>>>>>
>>>>>> Sent from my BlackBerry
>>>>> Cheers, Gene Heskett
>>>>> --
>>>>> "There are four boxes to be used in defense of liberty:
>>>>> soap, ballot, jury, and ammo. Please use in that order."
>>>>> -Ed Howdershelt (Author)
>>>>> If we desire respect for the law, we must first make the law respectable.
>>>>> - Louis D. Brandeis
>>>>> Genes Web page <http://geneslinuxbox.net:6309/gene>
>>>>>
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