Specifications

Software Configuration
3–21
Serial Handshake
The serial console device data format and the Little Board/486i serial port data format must match for the
devices to properly communicate. In addition, the hardware handshake behavior must be compatible.
Normally, a serial port’s Data Set Ready (DSR) and Clear To Send (CTS) input handshake signals must
be true (active) for the ROM BIOS to send data out. On the Little Board/486i, the hardware handshake
can be enabled or disabled with SETUP. When hardware handshaking is enabled, be sure to connect the
DSR and CTS signals to appropriate handshake signals on the external serial device’s interface connector.
As an alternative, loop the Little Board/486i’s serial output handshake signals to its input signals as
follows:
! DTR (out) to DSR (in)
! RTS (out) to CTS (in)
3.9.4 Serial Booting and Serial Programming
Serial console functionality has been expanded to incorporate two additional features useful in embedded
applications. The serial boot facility enables the Little Board/486i to boot from code downloaded
through a serial port in a manner similar to booting from a local hard disk or from a network. The serial
programming facility permits updating Flash memory devices installed in the byte-wide sockets over the
serial port. Refer to Ampro Application Note AAN-9403 for a complete description of these features.
Refer to the Ampro Common Utilities manual for descriptions of SERLOAD and SERPROG, utility
programs used to support serial booting and serial programming.
3.9.5 Using a Serial Modem
You can use any of the RS232C ports as a modem interface. You will not need to concern yourself with
serial port initialization since most PC communications programs control the serial port hardware directly.
If your program does not do this, use the DOS MODE command to initialize the port.
When installing a modem, be sure to connect appropriate input and output handshake signals, depending
on what your communications software requires. Standard PC-compatible serial modem cables that
connect all of the proper signals correctly are commonly available. The signal arrangement on the serial
port connectors is described in Chapter 2.
Many powerful communications programs are available to control modem communications. Some of these
programs offer powerful “script” languages that allow you to generate complex automatically functioning
applications with little effort.
3.10 MULTIMODE PARALLEL PORT
The enhanced parallel printer port is a superset of the standard PC-compatible printer port. It supports
four modes of operation:
! Standard PC/AT printer port—Centronics-type output only printer port, compatible with the
original IBM PC printer port.
! Bi-directional parallel port—Sometimes called a PS/2-compatible parallel port. It behaves the same
as the standard PC/AT port on outputs, and provides an input mode as well.
! Enhanced Parallel Port (EPP)—Bi-directional parallel port, compatible with the Standard and PS/2
ports, and adding automatic read- and write-cycle modes. Automatically generates input and output