Modems

Last night, I started checking my computer inventory for a modem that my sister could use to access the internet. I told her I would set her up with an old PC that I had, but discovered it had no modem built-in. I knew that I had a 56KB modem around here some where, but I have not found it yet. But what I did find was amazing, taking me back to 1979 and showing the changes that have evolved in home computer communications since then.

By the way, the term modem is short for modulator - demodulator. This is a way to convert a computer's digital data in a manner to transmit it over telephone lines. In the early days, this was done with an acoustic coupler in which a telephone handset was placed. These were built into old Teletype machines like I first used in 1969. The one shown here is from my first TI 99/4 home computer that I bought in 1979. These typically worked at 150 or 300 baud (bits per second). I also found other hardwired modems running at 1200, 2400, 4800, 9600 and 14,400 baud. As the technology advanced in speed, these would negotiate the highest speed they could operate on with the modem on the other end of the telephone line. When you dialed to connect to another computer, you would hear this chirpy, hashy noice, increasing in frequency until it matched what the other modem and the quality of your telephone connection could handle.

Starting around 2000, I have had Qwest DSL service that ran at about 256 Kbaud. Though I upgraded to their Deluxe DSL which was supposed to run up to 1.5 Mbaud, it never ran at half that speed and degraded back down to about the 256 Kbaud level last year. Finally, in December, I switched over to the Time-Warner Road Runner cable internet service. This evening, the cable modem speed has varied between 1.5 Mbaud and 4.8 Mbaud, probably averaging around 3 Mbaud. Imagine, over the last 25 years, we have experienced a 10,000 times increase in speed at least with a typical home computer. Dedicated commercial lines and the main internet trunk networks operate at much higher speeds.