dhu0 at uba0 csr 0160440
A DHU-11 provides 16 communication lines.
Normal I/O control parameters for individual lines are managed by ioctl(2) calls. Individual DHU-11 lines may be configured to run at any of 13 speeds (50, 200 and 38400 baud are not available); the speed may be set via getty(8) or stty(1) or may be communicated by other programs which utilize ioctl(2) such as ifconfig(8), see tty(4).
The DHU-11 driver normally uses input silos and delays receiver interrupts by 20 milliseconds rather than taking an interrupt on each input character.
The driver currently does not make full use of the hardware capabilities of the DHU-11, for dealing with XON/XOFF flow-control or hard-wired lines for example.
Although the devices are not the same, a DHU-11 can convince the DH-11 autoconfiguration code that it is a DH-11.
The 4 40-way cables are a pain.
dhu driver appeared in
4.3BSD. A new
showed up in NetBSD 1.1A.
Even if the
dhu hardware supports DMA, the
driver cannot make use of this capability.