lane@dalcs.UUCP (John Wright/Dr. Pat Lane) (11/16/88)
I've read that the serial port in the IBM PC and XT is based on the 8250
chip while for the AT, a 16450 chip is used. In my AT clone, I notice the
serial board has an 8250 on it which seems to work just fine. I'm wondering
what the difference between these two chips is, what differences there
typicallly are bewteen XT and AT serial ports (besides XT ports often being
paired with battery powered clock/calendar circuits), and if there is any
problem or disadvantage in having an 8250 based card in an AT clone.
Enlightenment appreciated.
--
John Wright ///////////////// Phone: 902-424-3805 or 902-424-6527
Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8
Cdn/Bitnet: lane@cs.dal.cdn Arpa: lane%dalcs.uucp@uunet.uu.net
Uucp: lane@dalcs.uucp or {uunet,watmath,utai,garfield}!dalcs!lane mru@unccvax.UUCP (Markus Ruppel) (11/18/88)
in article <3078@dalcs.UUCP>, lane@dalcs.UUCP (John Wright/Dr. Pat Lane) says: > Keywords: RS232, chips, AT, XT, I/O ports > > I've read that the serial port in the IBM PC and XT is based on the 8250 > chip while for the AT, a 16450 chip is used. In my AT clone, I notice the > serial board has an 8250 on it which seems to work just fine. I'm wondering > what the difference between these two chips is, 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...:-)) Markus Ruppel Dept. of Chemistry UNC Charlotte UUCP: ...!mcnc!mru ...!mcnc!unccvax!mru BITNET: ACC00MR1@UNCCVM
simon@ms.uky.edu (Simon Gales) (11/18/88)
In article <1232@unccvax.UUCP> mru@unccvax.UUCP (Markus Ruppel) writes: >in article <3078@dalcs.UUCP>, lane@dalcs.UUCP (John Wright/Dr. Pat Lane) says: >> I've read that the serial port in the IBM PC and XT is based on the 8250 >> chip while for the AT, a 16450 chip is used. In my AT clone, I notice the >> serial board has an 8250 on it which seems to work just fine. I'm wondering >> what the difference between these two chips is, >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." I believe that the 16450 has a larger internal buffer and can also handle higher baud rates. >Markus Ruppel <--------------------------------------------------------------------------> <--- Simon Gales@University of Ky 263-2285/257-3597 ---> <--- [ simon@ms.uky.edu ] | [ simon@UKMA.BITNET ] ---> <--------------------------------------------------------------------------> -- <--------------------------------------------------------------------------> <--- Simon Gales@University of Ky 263-2285/257-3597 ---> <--- [ simon@ms.uky.edu ] | [ simon@UKMA.BITNET ] ---> <-------------------------------------------------------------------------->
doc@holin.ATT.COM (David Mundhenk) (11/22/88)
In article <3078@dalcs.UUCP>, lane@dalcs.UUCP (John Wright/Dr. Pat Lane) writes: > I've read that the serial port in the IBM PC and XT is based on the 8250 > chip while for the AT, a 16450 chip is used. In my AT clone, I notice the > serial board has an 8250 on it which seems to work just fine. I'm wondering > what the difference between these two chips is, what differences there > typicallly are bewteen XT and AT serial ports (besides XT ports often being > paired with battery powered clock/calendar circuits), and if there is any > problem or disadvantage in having an 8250 based card in an AT clone. > I wish I had been aware of the AT using the 16450 chip if it's supposed to be better than the 8250. I recently bought a serial I/O card for my AT clone that uses the 8250 - I didn't see any that used a 16450. Anyway, I am using it with LapLink at 19,200 baud to transfer files, and it works just fine. Maybe someone with a more rigorous use for the serial port would be unhappy.... -Dave "Credo quia absurdum" ------------------------------------------------------------------ /^, , , . . , , , , , / } _, , , . __/ | /| / /| /| , , __, __/ /_ _, __, /_ /_./ (_l |/ / /_/ |/ |/. / |/ | /_/ / / /_/ / / /_ / / /\ Disclaimer: My opinions do not reflect those of anyone I work for or with, or anyone who does not look like me.
vo@micomvax.UUCP (Vladimir Orlt) (11/30/88)
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