CompuServe Messages

"Since doing a download and upload at the same time (besides the fact that uploads [to the libraries] are free anyway) would essentially double the time anyway…" Uploading while downloading under something like CIM shouldn't double the online time, at least from my experience (which doesn't include CIM). Assuming the files are roughly the same size, the transfer time should be the same as if it were occurring in one direction only. The data link, being full duplex (I've never known CIS to use HST modems), allows a 2400 baud modem to xfer at a full 2400bps IN BOTH DIRECTIONS, SIMULTANEOUSLY. Most of the time, we are wasting half of our modem bandwidth. Packet-switching protocols, which HMI must be, break up a single serial line into packets belonging to different logical data streams as needed. Since you can now have more than one logical stream of data flowing at once, it follows that they can flow in parallel if your data line supports full-duplex operation. DNet, for instance, allows many, many different data streams over a single serial line. If you 'download' 2 things at once, each trabsfer will take twice as long as it normally would — the data are both going in the same direction. BUT if you decide to upload and download, both will flow at full speed — the data are both going in opposite directions and effective throughput on a 2400bps data line is a full 4800bps. Although it does not matter much, the upload during a download would be closer to 'free' (chronologically) because the upload is explicitly going in the opposite direction; A CO goes in both directions with most of the data flowing in the same direction as a download, thus adding more time to your download. Like I said, it doesn't matter much. What matters is that something like HMI is available, however one decides to use it. It is up to the HMI/packet-switcher to intelligently handle the traffic for you. -Chris