RTTY (Radio Teletype) was the king of the ASCII transmission and was used all through the world
to transmit at 50 bauds.

PSK31 was introduced in the 1990's
Its bandwidth dropped from approximatively 120 kHz for RTTY to as narrow as 31.25 kHz in PSK31.


THROB was developed as an improvement of MFSK to take advantage of DSP (Digital Signal Processors)
MFSK developed by 1935
 MFSK16 is the newest "super-RTTY" mode to date.
 
 In 1996, packed radio and specially cluster-based TNC systems (hubmasters)
 can provide high speed packet radio, up to 256 kbps on the 33-cm (904-916 MHz)
 and 23-cm bands (1.3 GHz)

See:
Packet Radio Digital Modes
Amateur Radio History
Return to Amateur Radio in Hobbies or Personal Radio in Products.