I own a 64 and am interested in purchasing a modem. It seems the only modems available are 300 baud modems. Why is this? Can the 64 only operate at 300 baud?
Ki Jeong Yun
When using ordinary telephone lines, a communications rate of 300 baud (more properly, 300 bits per second-bps for short) is the most reliable. In addition, 300 bps modems are much more affordable than faster modems, and the 64 is a low-cost computer aimed at the home market. A 1200 bps modem would easily cost more than the computer itself.
The problem is that higher transmission rates pack the data more densely and therefore are more susceptible to errors from line noise. At 300 bps, only about 30 characters per second are transmitted. At 1200 bps, about 120 characters per second are sent, and a short burst of noise could cause a significant loss of data.
Also, it's important to remember that both ends of any telecommunications link must operate at the same speed. If you have a 1200 bps modem while most other 64 owners have the more common 300 bps modems, you'll be able to use the higher speed to communicate with only a limited number of other users.
The Commodore 64 is actually capable of exchanging data at up to 2400 bps through its serial port. By using the proper interface, it is possible to attach any RS-232 compatible modem to a 64 and program the port for whatever rate you wish. The quality of the phone line will be the limiting factor.
If you're shopping for a faster modem, watch for prices to drop significantly on 1200 bps modems in 1985. Several companies also introduced 2400 bps modems at the Fall COMDEX computer show in Las Vegas last November, but they're priced in the $800 range.