Specifications

Little Board/P5i Technical Manual
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3.9 OPERATION WITH DOS
The Little Board/P5i supports IBM’s PC-DOS or Microsoft’s MS-DOS, Version 3.3 or later, or any
version of Digital Research’s DR DOS as the disk operating system. Any differences between these
similar operating systems are noted in the text where applicable.
EMS Option—The Little Board/P5i can emulate the Lotus-Intel-Microsoft Expanded Memory
Specification Version 4.0 (LIM EMS 4.0), with the memory management capability of the Pentium CPU,
under control of a device driver. Such drivers are available with the newer versions of DOS. With
Microsoft MS-DOS, the driver is called EMM386.EXE.
Serial Ports—DOS normally supports the board’s four serial ports as COM1, COM2, COM3, and
COM4.
At boot time, DOS initializes the serial ports, assigning them their COM port designations and their
communication parameter settings. Although this might vary with different types and versions of DOS,
typical communication parameter settings are 2400 baud, even parity, 7 bits, and 1 stop bit.
Usually an application program that uses a serial port will access the port’s hardware and reinitialize the
communication parameters to other values, based on settings that the user has entered when configuring
the application program.
Parallel Port—The Parallel Printer port is normally the DOS LPT1 device. Most application software
uses LPT1 as the default printer port. If you enable the port, printing to it is automatic.
The following DOS commands can be used to test printing with the parallel printer:
A>COPY CONFIG.SYS LPT1
Prints contents of CONFIG.SYS
A>DIR >LPT1
Prints the directory
In addition, the <PrtSc> (Print Screen) key will print the contents of the video screen to the LPT1 device.
Also, you can use the Printer Echo function to print all characters typed on the keyboard. The command
<Ctrl-P> enables the Printer Echo function. Entering <Ctrl-P> again disables Printer Echo.
Disk Drives—Older versions of DOS require you to divide disk drives larger than 32M bytes into more
than one partition. More recent versions permit drives to be up to 2G bytes. Larger IDE drives require
Logical Block Addressing (LBA). Logical Block Addressing is supported by the ROM BIOS.
3.10 SERIAL PORTS
The four serial ports on the Little Board/P5i are standard PC-compatible ports based on the 16550-class
UART controller. This device provides increased performance by utilizing a 16-byte FIFO memory.
3.10.1 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
correctly connect all of the proper signals 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.