Path: utzoo!attcan!uunet!aplcen!samsung!shadooby!mailrus!ncar!tank!oddjob!rfl
From: rfl@oddjob.uchicago.edu (Bob Loewenstein)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Checking Serial drivers for pending chars
Message-ID: <6376@tank.uchicago.edu>
Date: 21 Nov 89 21:08:39 GMT
References: <10346@cadnetix.COM>
Sender: news@tank.uchicago.edu
Reply-To: rfl@oddjob.uchicago.edu (Bob Loewenstein)
Organization: U of Chicago - Astronomy & Astrophysics
Lines: 3


SerGetBuf is the call you want. It tells how many characters have 
come into the buffer since the last read.