greg@jimi.cs.unlv.edu (Greg Wohletz) (04/26/88)
Does the dz-11 support hardware flow control under 4.3BSD? If not, do any of the serial board drivers? If not, does anyone have versions that do? --Greg greg@jimi.cs.unlv.edu <@relay.cs.net:greg@jimi.cs.unlv.edu>
guy@gorodish.Sun.COM (Guy Harris) (04/27/88)
> Does the dz-11 support hardware flow control under 4.3BSD? The term "hardware flow control", without further qualification, is meaningless. I know of at least *three* different schemes for using various RS-232 lines for flow control: 1) If CD drops, suspend output; when CD comes back up, resume output. No reverse channel. 2) Raise RTS. If CTS drops, suspend output; when CTS comes back up, resume output. No reverse channel. 3) Same as 2), only the host uses RTS as a reverse flow control channel, instead of as "Request To Send"; i.e., RTS and CTS are crossed, and the host drops RTS when it's not ready for more input. There may be a fourth scheme, which is to 1) as 3) is to 2). According to "dzreg.h", at least one of the DZ11/DZ32 supports all of the aforementioned modem control lines. However, the DZ and tty drivers support only the flow control mechanism described in 1) above. > If not, do any of the serial board drivers? I think the other serial board drivers do the same; they just hand CD up/down indications to the tty driver, which uses that to perform flow control if MDMBUF is set.