rit@killdeer.Stanford.EDU (Jean-Francois Rit) (06/13/91)
Can the Next ports run at 57600 baud RS422? This seems to be a
requirement to drive some printers...
All I could get from the man pages is that zs can run at any of 16
speeds and that tty speeds are:
B0 0 (hang up dataphone)
B50 1 50 baud
B75 2 75 baud
B110 3 110 baud
B134 4 134.5 baud
B150 5 150 baud
B200 6 200 baud
B300 7 300 baud
B600 8 600 baud
B1200 9 1200 baud
B1800 10 1800 baud
B2400 11 2400 baud
B4800 12 4800 baud
B9600 13 9600 baud
EXTA 14 19200 baud
EXTB 15 38400 baud
That's 16 if you count speed 0.
Am I doomed?
J-F Ritddj@zardoz.club.cc.cmu.edu (Doug DeJulio) (06/14/91)
In article <1991Jun13.152426.20007@neon.Stanford.EDU> rit@killdeer.Stanford.EDU (Jean-Francois Rit) writes: >Can the Next ports run at 57600 baud RS422? This seems to be a >requirement to drive some printers... > >All I could get from the man pages is that zs can run at any of 16 >speeds and that tty speeds are: > > B0 0 (hang up dataphone) > B50 1 50 baud > B75 2 75 baud > B110 3 110 baud > B134 4 134.5 baud > B150 5 150 baud > B200 6 200 baud > B300 7 300 baud > B600 8 600 baud > B1200 9 1200 baud > B1800 10 1800 baud > B2400 11 2400 baud > B4800 12 4800 baud > B9600 13 9600 baud > EXTA 14 19200 baud > EXTB 15 38400 baud I'm pretty sure the hardware can do better. I've been wondering about the possibility of redefining EXTA and EXTB to be something different. Ideally, I'd like both 56kbaud asynch and 64kbaud SYNCHRONOUS serial on my NeXT, -- the first for a SLIP connection to a roommate's Amiga3000, the other for our house's SLIP connection to the internet. Given those, I'd have no use for 19.2kbaud or 38.4kbaud. Can anyone tell me anything about the feasability of this plan? Is this sort of modification to the serial port device driver something we can do in a loadable kernel module? Does anyone know for a fact what the limits of the hardware are? Hm, appletalk is really just a very high speed serial line protocol, isn't it? -- Doug DeJulio ddj@zardoz.club.cc.cmu.edu
scott@mcs-server.gac.edu (Scott Hess) (06/14/91)
In article <1991Jun13.152426.20007@neon.Stanford.EDU> rit@killdeer.Stanford.EDU (Jean-Francois Rit) writes:
Can the Next ports run at 57600 baud RS422? This seems to be a
requirement to drive some printers...
The super-serial chips, or whatever they are called (it's late,
alright?) are not supposed to run any faster than 38400, or
so I've heard. The problem is mostly that they are simply older
technology (albeit well-proven). I've heard various rumors about
various devices that _can_ go faster - via the SCSI or DPS
ports - but, alas, as shipped Unix can't do greater than
38,400.
I doubt there are any printers with such limits. They'll probably
run faster at that speed, but they probably don't _require_ it.
The reason being that NeXT's serial io is as good as most PCs,
which means that it's probably capable of accepting lower
speeds. Would seem sort of stupid not too, I'd think . . .
Later,
--
scott hess scott@gac.edu
Independent NeXT Developer Graduated GAC Undergrad!
<I still speak for nobody>
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New: RR#4 Box 227 Pipestone, MN 56164 (507) 825-2788bob@MorningStar.Com (Bob Sutterfield) (06/14/91)
In article <1991Jun13.152426.20007@neon.Stanford.EDU> rit@killdeer.Stanford.EDU (Jean-Francois Rit) writes: Can the Next ports run at 57600 baud RS422? All I could get from the man pages is that zs can run at any of 16 speeds and that tty speeds are: [50 thru 38400] The highest supported async clock speed, with the standard device driver, is defined in <sys/ttydev.h> as 38400. I haven't yet tested to see whether they can achieve that in real throughput. If one wished different values than those (higher or lower or in between) then one would need to supply a custom device driver, complete with custom ioctls. The highest sync clock speed we recommend with our X.25 daemon on the NeXT serial ports is 19200, because that's the highest speed at which it runs reliably. We have clocked it higher (e.g. 38400), but it gets more underruns the higher you push the speed. X.25 "works" at those speeds only because of the redundancy of the higher-level protocols, which cause frames to be resent when needed. In article <1991Jun13.182809.23141@zardoz.club.cc.cmu.edu> ddj@zardoz.club.cc.cmu.edu (Doug DeJulio) writes: I'm pretty sure the hardware can do better. The same X.25 daemon code runs reliably at 64K on a SPARCstation-1, which uses the same Zilog 8530 serial interface chip, so yes the hardware can do better. We run X.25 over RS232 (sync) on our VME boards using the 8530 at speeds over 500K, so yes some parts of the hardware can do much better. (You don't want to run RS232 async at very high speeds, because the waveforms begin to get distorted by the capacitance.) Our X.25 daemon's serial interface speed is limited on the NeXT's native ports because of certain design misfeatures of the NeXT Mach 2.* 8530 interrupt service routines. This has been reported to NeXT as a bug. Also, the SPARC architecture is much better at servicing interrupts than is the Motorola 68K found in (today's :-) NeXT. In article <SCOTT.91Jun14005609@mcs-server.gac.edu> scott@mcs-server.gac.edu (Scott Hess) writes: The super-serial chips ... are not supposed to run any faster than 38400, or so I've heard. 38400 is the highest async serial speed found in <sys/ttydev.h> on any UNIX system I've encountered. The problem is mostly that they are simply older technology (albeit well-proven). The 8530 can run fast just fine. As above, they manage 64K sync just fine in other UNIX systems, when those systems service their interrupts correctly. I've heard various rumors about various devices that _can_ go faster - via the SCSI or DPS ports - but, alas, as shipped Unix can't do greater than 38,400. Our SCSI-attached sync serial interface runs at T1 speeds and better, but it doesn't use the 8530. A serial async device driver either for its ports or for the NeXT-native 8530s could define whatever speeds it likes, but you probably won't get much over 64K async on the native NeXT ports.
hardy@golem.ps.uci.edu (Meinhard E. Mayer (Hardy)) (06/15/91)
I have run kermit transfers at 38400 baud (MSKermit 3.01 to NeXT Kermit 5.0), and am printing to a LaserJetIIP at 19200 Baud, if that is any help. Greetings, Hardy -------****------- Meinhard E. Mayer (Hardy); Department of Physics, University of California Irvine CA 92717; (714) 856 5543; hardy@golem.ps.uci.edu or MMAYER@UCI.BITNET