Path: utzoo!attcan!uunet!van-bc!ubc-cs!alberta!aunro!ersys!davem From: ersys!davem@nro.cs.athabascau.ca Newsgroups: comp.dcom.modems Subject: Re: USR 9600 baud dual standard Message-ID: Date: 15 Oct 90 14:34:49 GMT References: <539.2718D7B1@zswamp.fidonet.org> Organization: Edmonton Remote Systems, Edmonton, AB, Canada Lines: 26 root@zswamp.fidonet.org (Geoffrey Welsh) writes: > > > From: john@jwt.UUCP (John Temples) > > Organization: Private System -- Orlando, FL > > > > How can you pump data at 19.2k bps into a modem which can only > > transmit it at 17-18k bps without using flow control? > > If they are only using windowed protocols (e.g. UUCP-g), the TB's 1.75K > buffer will keep ahead of the host's transmissions. > -- The HST and other error correcting modems use the CTS and DSR lines to "handshake" with their host computer, telling it when to stop sending data while the modem deals with what's already in its buffer. When it's ready for more, the modem sets the line high and the computer starts sending again. It's not a new concept; serial printers have operated like this for years and parallel printers use a ready/busy line in the same manner. Dave McCrady | ersys!davem@nro.cs.athabascau.ca Edmonton Remote Systems | 13324-138 Street | BBS: (403)-454-6093 300-9600 bps (HST) Edmonton, AB Canada T5L 2B4 | USENET (403) 452-3254 300-2400 bps