SMODEM

Smodem refers to a bidirectional protocol for file transfer used between modems and the MS-DOS program in which the protocol is implemented, both of which were developed by the Finnish Arisoft. It was mainly used in bulletin board systems because it could transfer files in both directions at the same time and allowed users to chat with each other with AriSoft's GroupChat software. Other popular bidirectional protocols such as BiModem, HS/Link and HydraCom also offered a chat option with the operator, but not with the system's other users.

Smodem refers to a bidirectional protocol for file transfer used between modems and the MS-DOS program in which the protocol is implemented, both of which were developed by the Finnish Arisoft. It was mainly used in bulletin board systems because it could transfer files in both directions at the same time and allowed users to chat with each other with AriSoft's GroupChat software. Other popular bidirectional protocols such as BiModem, HS/Link and HydraCom also offered a chat option with the operator, but not with the system's other users. \frac{max\ packetsize}{max\ packetsize\ +\ frame\ size} = \frac{1024}{1024+5} = 0.9951 = 99.5\% If the packet size is limited to 256 bytes, the efficiency is 98.1%, which is still better than original Zmodem. If the data link can not transfer some special characters, then the traditional character encapsulation mode can be activated. In this mode the selected character codes are encapsulated, which reduces the performance by about 0.4% + additional 0.4% for every selected character code. In case the data link is limited to seven data bits, a special bit collection mode can be activated. The highest bits for every seven bytes are collected to one byte (which is eight bits under normal conditions). This collection reduces the performance about 12.4% and doubles the character encapsulation capacity. The maximum transfer line correction mode of MSLP uses five characters to transmit four characters that use only printable 7-bit ASCII codes (Ascii85). This mode should work on almost every non-transparent transmission line. The maximum correction mode reduces the performance by 20%. It should only be used for test purposes if the default settings do not work or if the limitations of transfer line are unknown or too complex to handle with separate adjustments. ==References== The Smodem Techinfo.doc HydraCom ==External links== Arisoft Oy

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