jhc (04/22/83)
I have an Ungermann-Bass Ethernet installation which allows three methods of programming flow control - ^S/^Q, toggling CTS (and responding to RTS), and toggling DSR(and responding to DTR). This is great, except that my DZ's don't understand CTS and so I have to use ^S/^Q, which screws up EMACS when the NIU flow-controls the VAX (which happens ALL the time). I thought I would try to put something into the tty driver that would understand hardware flow control, and supply same if necessary. I have no particular hardware in mind, (actually I have a full set of leads available on the board I am thinking of, but anyway). My question is has anyone else done this, or thought about it, or even implemented it. I am familiar with the Berkeley 'tandem' concept and it seems OK, but it only does ^S/^Q. My current thoughts lean towards putting some extra bits into the c_lflag field or tty(4)/termio(7), and doing user-level flow control via the TCXONC ioctl call (that should be 'of' earlier, not 'or'). The c_lflag field would determine the type of flow control (CTS/RTS (my favourite), DSR/DTR, or ^S/^Q), and the ioctl call would tell the driver when to turn it on or off. ^S and ^Q would be passed through undisturbed in all cases. Any comments, flames, ideas or questions please let me know. All replies acknowledged (not for ARPA - I can't get through). I will summarize to the net iff there are 'sufficient' responses. Jonathan Clark ABI Holmdel [houx*|ariel]!hou5a!jhc