Input and Output Control

The console is used as the primary means of communication between OpenBoot and the user. The console consists of an input device, used for receiving information supplied by the user, and an output device, used for sending information to the user. Typically, the console is either the combination of a text/graphics display device and a keyboard or an ASCII terminal connected to a serial port.

The configuration variables related to the control of the console are:

• input-device

• output-device

• screen-#columns

• screen-#rows

You can use these variables to assign the power-on defaults for the console. These values do not take effect until after the next power cycle or system reset.

Selecting Input and Output Device Options

The input-device and output-device variables control the firmware's selection of input and output devices after a power-on reset. The default input-device value is keyboard and the default output-device value is screen. The values of input-device and output-device must be device specifiers. The aliases keyboard and screen are often used as the values of these variables.

When the system is reset, the named device becomes the initial firmware console input or output device. (If you want to temporarily change the input or output device, use the input or output commands described in Chapter 4, Using Forth Tools)

To set ttya as the initial console input device, type:

ok setenv input-device ttya
ok

If you select keyboard for input-device, and the device is not plugged in, input is accepted from a fallback device (typically ttya) after the next power cycle or system reset. If you select screen for output-device, but no frame buffer is available, output is sent to the fall-back device after the next power cycle or system reset.

To specify an SBus frame buffer as the default output device (especially if there are multiple frame buffers in the system), type:

ok setenv output-device /sbus/SUNW,leo 
ok 

Serial Port Characteristics

The following values represent the typical range of communications characteristics for serial ports:

• baud = 110, 300, 1200, 2400, 4800, 9600, 19200, or 38400 bits/second

• #bits = 5, 6, 7, or 8 (data bits)

• parity = n (none), e (even), or o (odd), parity bit

• #stop = 1 (1), . (1.5), or 2 (2) stop bits

rts/cts and xon/xoff handshaking are not implemented on some systems. When a selected protocol is not implemented, the handshake variable is accepted but ignored; no messages are displayed.