NAME

tb − tablet

DESCRIPTION

tb controls the Hitachi Data Tablet.  tb is a STREAMS module, pushed on top of an RS-232 line driver. 

The user can not send data to the tablet, but can receive data.  The data are encapsulated in the structure gin format as defined in <machine/gin.h>:

struct gin {
unsigned longgin_msec;
unsigned longgin_mux_id;
unsigned shortgin_id;
chargin_dev;
chargin_dim;
longgin_buttons;
shortgin_data[NDIM_GIN];
};

gin_id is GID_TBL.  gin_dev is GDEV_ABS.  gin_dim is two (2).  gin_buttons indicates which button is being changed.  The first data (gin_data[0]) specifies the x-coordinate delta and the second data (gin_data[1]) for the y-coordinate. 

The default mode settings are:

resolution: 0.001 inch.  output mode: “incremental” mode in that data will be output when the movement of the pen or cursor in the x/y direction is above 0.1 millimeter greater than the set resolution. 

output rate: fastest (limited by the RS-232C baud rate). 

origin: origin is set at the left bottom corner of the tablet.  Thus, all xy coordinate data are positive. 

format: packet binary data format is used between the tablet hardware and the tb module. 

For the standard configuration, the tablet is connected to the serial port “c” (that is, tty line 2).  Thus, /dev/tb is linked to /dev/tty2.  The user conventionally opens /dev/tb, (via open(2)), pops off the tty line discipline, (via I_POP ioctl), and pushes the tb(7) module, (via I_PUSH ioctl). 

FILES

/dev/tb

SEE ALSO

streamio(7), gin(7)
Hitachi Data Table Digitizer HDG-0812 HDG-1217 Instruction Manual, Hitachi Seiko, Ltd. 

September 02, 1992