Many Fidonet mailers, like Binkley or T-Mail supported Hydra which was novel multi-streaming bidirectional serial protocol. You could download several files wh

Many Fidonet mailers, like Binkley or T-Mail supported Hydra which was novel multi-streaming bidirectional serial protocol. You could download several files while uploading your outbound mail at the same time. It was very useful for those lucky possessed 28800 baud modems like ZyXEL Elite or US Robotics Courier (mid/late 90th).