scc - Zilog serial communications interface
scc0 at ioasic? offset ?
scc1 at ioasic? offset ?
The scc driver provides support for the Zilog 8530 Serial
Controller (SCC) via the IOCTL asic on TURBOchannel-based
alphas (the DEC
3000 series). Each scc device has two serial ports.
Input and output for each line may set to one of following
50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800,
38400, or 57600. Speeds up to 230400 are supported by the
chip and the
motherboard, but speeds higher than 57600 do not work reliably without an
external clock signal.
The mapping from units to serial-hardware outlets is idiosyncratic.
The scc driver first appeared in 4.4BSD.
The IOCTL asic provides internal DMA channels that can be
transfer up to 4096 bytes of data into, or out, of an SCC
software intervention. This feature of the ioctl asic is
not yet supported.
The mapping from device-special files (major and minor number) to chip
and port is arguably backwards.
OpenBSD 3.6 March 7, 1998
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