All rights reserved.
This code is derived from software contributed to Berkeley by
the Systems Programming Group of the University of Utah Computer
Science Department.
%sccs.include.redist.man%
@(#)dcl.4 5.1 (Berkeley) 06/29/90
Each line attached to the 98628A behaves as described in tty (4). Input and output for each line may set to one of following baud rates; 0, 50, 75, 110, 134.5, 150, 200, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200. See tty (4) for the encoding.
Flags should be set to 1 if the line should be treated as hard-wired with carrier always present, or to 0 if modem control is desired.
Use HP cable "98626 & 98628 opts.002, RS232-C DCE CABLE, 5061-4216" to attach non-modem devices. Use HP cable "98626 & 98628 opts.001, RS232-C DTE CABLE, 5061-4215" to attach modems.
The 98628A has a 256 byte input silo and a 256 output silo. Input interrupts happen on a per character basis.
The high water and low water marks in the kernel tty routines are totally inappropriate for a device like this with a large input buffer. Don't use tandem mode if possible. A fast system can handle input at 19.2K baud without receive overflow. For output to devices that make heavy use of XON/XOFF a write size of less then 256 will improve performance marginally.