Specifications

Hardware Configuration
2–10
Note
If you change the amount of memory installed, you must run
SETUP again to save the new value in the Configuration
Memory.
2.4.1 Shadowing
One way to improve system performance is to “shadow” the ROM BIOS and video BIOS. When the
system operates directly from ROM code, it accesses an 8-bit memory device. When the ROM
contents are shadowed, the contents are copied into system DRAM where they are accessed as 32-bit
wide data. Shadowing a BIOS ROM substantially enhances system performance, especially when an
application or operating system repeatedly accesses the ROM. ROM BIOS shadowing is built into the
Ampro Extended BIOS. There is no user setting. Shadowing the video BIOS is a SETUP option. For
information about how to set the video BIOS shadowing option, refer to the SETUP section in
Chapter 3.
2.4.2 Expanded Memory and Extended Memory
Memory above the 1 megabyte boundary is called “extended” memory. It is a contiguous linear block
of memory. Some programs require that memory be available as EMS memory. The EMS memory
standard makes memory available as pages rather than as a contiguous block. The exact manner for
accessing EMS memory is defined in the LIM 4.0 specification.
You can convert the board’s extended memory into expanded memory using DOS EMS emulation
utilities. Current versions of DOS provide EMS emulation utilities that conform to the LIM 4.0
specification. Refer to your DOS technical documentation for instructions for using their EMS
emulation utility.
2.5 MATH COPROCESSOR
The 80486 CPU contains a built-in floating point math coprocessor. There are no configuration
jumpers or options for the math coprocessor.
2.6 SERIAL PORTS (J11, J13)
The Little Board/486i provides four standard RS232C serial ports at J11 and J13. You can use the
serial ports for printers, modems, terminals, remote hosts, or other RS232C serial devices. Many
devices, such as printers and modems, require handshaking in one or both directions. Consult the
documentation for the device(s) you use for information about handshaking and other interface
considerations.
All ports support software selectable standard baud rates up to 115.2.2K bits/second, 5-8 data bits,
and 1, 1.5, or 2 stop bits. Note that the IEEE RS232C specification limits the serial port to 19.2K
bits/second on cables up to 50 feet in length.
2.6.1 I/O Addresses
The serial ports appear at the standard port addresses as shown in Table 2-6. These are fixed
assignments and cannot be changed. Each serial port, however, can be independently disabled using
the SETUP function, freeing its I/O addresses for use by other devices installed on the PC/104
expansion bus. For information about serial port configuration using SETUP, see Chapter 3.