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RC(4) Device Drivers Manual RC(4)


rcRISCom/8 multiport card


device isa
device rc


The RISCom/8 is an eight port ISA RS-232C communications multiplexer with a built in RISC processor. It uses a block of sixteen I/O ports in the range 0x200 to 0x3f0 selectable by on-board switches or jumpers. The block must be aligned on a sixteen port boundary. The jumper-selectable hardware interrupt level may be set to be detected during system initialization using settings found in the /boot/device.hints file.

This driver is mostly based on the Cirrus Logic CL-CD180 driver.


The rc driver provides support for the SDL Communications RISCom/8 boards.


The following driver specific error messages may be reported:

rc%d channel%d: interrupt-level buffer overflow
An internal buffer overflow error has occurred on the listed channel. The rc driver will need to be reloaded to correct this.
rc%d: Bad char chan %d
The channel has obtained a bad set of characters.
rc%d: Got extra chars chan %d
The rc driver got more characters than expected on the channel shown.
rc%d: data mismatch chan %d ptr %d (%d != %d)
Data sent from channel %d to the rx buffer was different then expected.
rc%d: channel %d command timeout, rc.c line: %d
A command timeout has occurred on the channel, the src/sys/dev/rc/rc.c file can be consulted for more information.


tty(1), ttyname(3), sio(4), tty(4), device.hints(5), comcontrol(8), getty(8), mutex(9), splx(9)


The rc driver first appeared in FreeBSD 2.0.5. This manual page first appeared in FreeBSD 5.3.


This manual page was written by Tom Rhodes <>.


The rc driver code still uses the spl(9) functions. These should be replaced by mutex(9) functions.

The various ttyld_*() functions should be documented.

March 18, 2005 Debian