0 Modem

Modem (Modulator-Demodulator) was equipment that today often is used to carry out the connection to the internet, especially through the telephone channel. Physically, the modem could be distinguished as the internal modem and the external modem. By that, we knew the distribution to be based on the speed and his procedure, that take the form of software or hardware the modem. There were several distributions again that his characteristics were more technical, like error control, the data compression protocol, et cetera, but the distribution of this kind will not be discussed by us in this article.

The Eksternal modem and Internal

Like was drawn from his name, external modem equipment was outside CPU. Modem external was connected to CPU through port COM or USB. Modem this kind usually uses the source of the tension was separated took the form of the adaptor. The use profit of this kind modem was portabilitas him that was good enough so as easy was moved-moved to be used in the other computer. By that by using the external modem, might not be slot the expansion that was sacrificed so as to be able to be used for the other need, especially if mainboard that was used only provided a little slot the expansion. The external modem was also supplemented with indicator light that facilitated us to monitor the status of the modem. His loss, his price was more expensive compared with the internal modem. The external modem also needed the special place to place him despite small.

Was different from the external modem, the internal modem was installed directly in CPU. physically the internal modem took the form of one card that tertancap to some slot the expansion in mainboard, usually in slot Isa or PCI. Penggunaan of this kind modem had several profits, including being more frugal the place and from the aspect of the price was more economical compared with the external modem. Because of being installed in CPU, then this kind modem did not need the adaptor as in the case of the external modem so as the system was apparently briefer without having many milling cables that could give the impression was not neater. Nevertheless, the internal modem had the weakness took the form of the nonexistence of the indicator as that could be met to the external modem. As a result rather was difficult to monitor the status of the modem (although could be carried out through software). Moreover, the internal modem did not use the source of the tension personally until must be rationed from power supply to CPU. Panas from components in the series of the internal modem also will increase the temperature in the CPU box.

The speed of Modem

Speed of a modem was measured with the unit bps (bit per second) or Kbps (kilobit per second). The size varied, between 300 bps and 56,6 Kbps, but the general speed is used today revolved between 14,4 and 56,6 Kbps. It was increasingly high that his speed was definitely increasingly good because of shortening connection time and saving the telephone credit cost. The speed of the connection also really depended on the quality of the telephone channel that was used. The modem 56,6 Kbps usually very rare could achieve the speed of his peak. Generally the fastest connection that could be achieved through the conventional telephone channel was revolving between 45-50 Kbps to downstream, depended the distance from the centre of the telephone channel that was used (increasingly close definitely increasingly good), whereas to upstream maximal only as big as 33.6 Kbps. This was linked with the limitations of the telephone channel that indeed basically was not drafted for data communication have a speed high.

The modem was based on Hardware and Software
Apart from the two distributions above, we also knew the term hardware or software the modem. The modem that worked in a hardware manner used chip especially to handle functions of data communication, whereas in software the modem, this work was taken over by a program driver.

The use software the modem will be enough to load the CPU work, and therefore definitely needed the system with processor that was fast (was suggested minimal used processor Pentium 200 MHz). The decline in the performance would really was felt when using this kind modem. A machine was based on Celeron 400 for example, only could work was proper for PC Pentium Classic during online with make use of software the modem. Physically almost did not have the characteristics that menyolok that distinguished between the two modem kinds. Nevertheless, today almost all the internal modem was based on PCI available in the market was software the modem. This kind modem is generally sold with the price that was far more cheaper compared with the based modem hardware.

Because of the availability factor driver, then software the modem generally only could work in the OS Windows environment so as this modem kind also often was acknowledged as Winmodem. His profit lately several producers gave the support for Linux for software their output modem.

The meaning of the Eksternal Modem

OH Indicator: Off Hook
Meaning that that the modem was working. If the telephone set, OH will be on when the handle was lifted and died when the handle was placed.

CD: Carrier Detect
Meaning that whether being carrier that was sent from the modem that was contacted or not. When having the connection with the other modem, CD light will be switched on.

AA: the Answer
Fasilitas car the modem that could answer automatically the call from the other modem. If the AA indicator was on, the modem could do handshaking automatically.
EC: Error Control
Fasility the modem for the correction error. The EC indicator that was on showed correction facilities error the modem was active.

TD: Transmit Data
Indikator that will be on when the modem was sending the data. Rd: Receive Data Indikator that will be on when the modem accepted the data.

DTR: the Terminal Ready
Indikator Data that showed the modem was ready to be used to carry out the connection to the other modem