Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uunet!snorkelwacker!bloom-beacon!eru!luth!sunic!maxim!prc From: prc@erbe.se (Robert Claeson) Newsgroups: comp.unix.questions Subject: Re: What do all the different parity options mean? Keywords: parity space mark Message-ID: <1038@maxim.erbe.se> Date: 7 Dec 89 08:05:18 GMT References: <4090@amelia.nas.nasa.gov> Organization: ERBE DATA AB, Jarfalla, Sweden Lines: 30 In article <4090@amelia.nas.nasa.gov>, izen@amelia.nas.nasa.gov (Steven H. Izen) writes: : I know what even parity and odd parity are, but what does *space* or : *mark* mean in a parity choice? Space = parity always cleared. Mark = parity always set. : Also, I think I understand what happens when the bits/parity is 8/none : or 7/even or 7/odd. But where is the parity bit stored when 8/even is : used? Yes. The parity bit is *not* part of the data sent, but of the *protocol* used to send the data. Therefore, parities and such have more to do with start and stop bits than with the data bits. Any reasonable tty driver should strip off all *protocol* information (including software flow control) and only pass you the interesting stuff, ie the data without any parity. So, 7 data bits and even parity is really sent as <7 data bits> . Some weird protocols uses two or even one-and-a-half stop bit. Therefore, 8 data bits and even parity is sent as <8 data bits> . Nothing strange about it. : Is there any good introductory reference to this? Not as far as I know, but I'd like to see one. -- Robert Claeson E-mail: rclaeson@erbe.se ERBE DATA AB