Abstract: A rapidly responsive, computer-based education system is described wherein a large central computer which is adapted to store and execute educational software and to provide a high speed data output stream of multiplexed data frames, communicates with a plurality of remotely located, keyboard actuated display terminals. Communications are accomplished in the forward channel via a satellite link with reverse channel communications being via one or more dedicated telephone lines. The forward channel satellite link is able to accept data at multi megabit rates and to service tens of thousands of user terminals per satellite transponder. The reverse channel telephone line, while only able to accept data rates in the kilobit per second range, accommodates outputs from hundreds of user operated terminals because of the low data rates generated by user operated terminals.

Abstract: A multiple access communications system links a plurality of geographically dispersed subscriber locations (each of which including a transmitter and receiver) with a central location (also including a transmitter and receiver). Multiple access communication is required in the direction from the subscriber transmitters to the central receiver. In order to maintain stability, a subscriber/transmitter which unsuccessfully transmits (due to a collision with a transmission from another subscriber) will retransmit. Multiple succeeding unsuccessful transmissions at any subscriber result at that subscriber in increasingly longer delays between successive transmissions.