Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!nrl-cmf!ames!ubvax!versatc!mips!prls!philabs!micomvax!vo From: vo@micomvax.UUCP (Vladimir Orlt) Newsgroups: comp.sys.ibm.pc Subject: Re: What is the difference between XT and AT serial ports Message-ID: <1394@micomvax.UUCP> Date: 29 Nov 88 16:56:31 GMT References: <3078@dalcs.UUCP> <1232@unccvax.UUCP> Reply-To: vo@micomvax.UUCP (Vladimir Orlt) Organization: Philips Electronics Ltd. (TDS - Montreal) St. Laurent QC, Canada Lines: 17 In article <1232@unccvax.UUCP> mru@unccvax.UUCP (Markus Ruppel) writes: >From the National Semiconductor data sheet: > > "The NS16450 is an improved specification version of the INS8250A > Asynchronous Communications Element (ACE). The improved specifica- > tions ensure compatibility with the NS32016 and other state-of-the > -art CPUs. Functionally, the NS16450 is equivalent to the INS8250A." > (typos mine...:-)) There is a difference between the NS16450 and the 8250 (I don't know the difference between the 8250 and the 8250A); the 16450 interrupt line remains active until all of the UART's pending/active interrupts are serviced (by reading the status register), whereas the 8250's interrupt line strobes after each of these interrupts is cleared. Vlad the re-mailer ...!philabs!micomvax