NAME

zs − zilog 8530 SCC serial comunications driver

SYNOPSIS — SUN-3

device zs0 at obio ? csr 0x20000 flags 3 priority 3
device zs1 at obio ? csr 0x00000 flags 0x103 priority 3

SYNOPSIS — SUN-2

device zs0 at virtual ? csr 0xeec800 flags 3 priority 3
device zs1 at virtual ? csr 0xeec000 flags 0x103 priority 3
device zs2 at mbmem ? csr 0x80800 flags 3 priority 3
device zs3 at mbmem ? csr 0x81000 flags 3 priority 3
device zs4 at mbmem ? csr 0x84800 flags 3 priority 3
device zs5 at mbmem ? csr 0x85000 flags 3 priority 3

DESCRIPTION

The Zilog 8530 provides 2 serial communication ports with full modem control in asynchronous mode.  Each port behaves as described in tty(4). Input and output for each line may independently be set to run at any of 16 speeds; see tty(4) for the encoding.

Of the synopsis lines above, the line for zs0 specifies the serial I/O ports provided by the CPU board, the line for zs1 specifies the Video Board ports (which are used for keyboard and mouse), the lines for zs2 and zs3 specify the first and second ports on the first SCSI board in a system, and those for zs4 and zs5 specify the first and second ports provided by the second SCSI board in a system, respectively. 

Bit i of flags may be specified to say that a line is not properly connected, and that the line i should be treated as hard-wired with carrier always present.  Thus specifying “flags 0x2” in the specification of zs0 would cause line ttyb to be treated in this way. 

To allow a single tty line to be connected to a modem and used for both incoming and outgoing calls, a special feature, controlled by the minor device number, has been added.  Minor device numbers in the range 0 − 127 correspond directly to the normal tty lines and are named tty∗.  Minor device numbers in the range 128 − 256 correspond to the same physical lines as those above (i.e. the same line as the minor device number minus 128) and are (conventionally) named cua∗.  The cua lines are special in that they can be opened even when there is no carrier on the line.  Once a cua line is opened, the corresponding tty line can not be opened until the cua line is closed.  Also, if the tty line has been opened successfully (usually only when carrier is recognized on the modem) the corresponding cua line can not be opened.  This allows a modem to be attached to /dev/ttya (usually renamed to /dev/ttyd0) and used for dialin (by enabling the line for login in /etc/ttys) and also used for dialout (by tip(1C) or uucp(1C)) as /dev/cua0 when no one is logged in on the line.  Note that the bit in the flags word in the config file (see above) must be zero for this line. 

FILES

/dev/tty[a, b, s0-s3]
/dev/ttyd[0-9, a-f]
/dev/cua[0-9, a-f]

SEE ALSO

tty(4)

DIAGNOSTICS

zsnc: silo overflow. 
The character input silo overflowed before it could be serviced.

Sun Release 3.2  —  Last change: 16 September 1985