Product Reference
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Operation with DOS
The Little Board/486e CPU 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.
Caution
Sometimes MS-DOS is customized by a manufacturer for a specific
system and may not work on the Little Board/486e CPU. Use DR DOS
(supplied by Ampro), IBM PC-DOS (supplied by IBM), or the generic
version of MS-DOS (supplied by Microsoft on an OEM basis).
EMS Option—The Little Board/486e CPU can emulate the Lotus-Intel-Microsoft Expanded
Memory Specification Version 4.0 (LIM EMS 4.0), with the memory management capability of the
80486DX2/4 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 seri al port s as COM1, COM2, COM 3, and
COM4.
At boot time, DOS initializes the serial ports, assigning them the ir CO M port de signa tion s and
their communication parameter settings. Although this might vary with different types and
versions of DOS, typical communication parameter settings are 240 0 baud, eve n par ity, 7 bits, and
1 stop bit.
Usually an application program that uses a serial port w ill access the po rt’s h ardware and
reinitialize the communication parameter s to o ther value s, ba sed on se ttin gs tha t the u ser h as
entered when configuring the application program.
Parallel Port—The Parallel Printer port is normally the DOS LPT1 de vice. Most applic atio n
software uses LPT1 as the default printe r por t. If you enab le the por t, prin ting to it i s auto matic .
The following DOS commands can be used to tes t prin ting w ith the par allel p rinter :
A>COPY CONFIG.SYS LPT1 Prints contents of CONFIG.SYS
A>DIR >LPT1 Prints the director y
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 f unc tion to pr int al l cha rac ters type d on the keybo ard.
The command <Ctrl-P> enables the Printe r Ec ho f unctio n. Enter ing <Ctrl- P> a ga in di sable s
Printer Echo.
Disk Drives—Older versions of DOS require you to divid e di sk driv es larg er than 32M byte s into
more than one partition. More recent versions permit drives to be up to 2G by tes, thoug h IDE
drives are BIOS limited to 512M bytes. Larger IDE drives typically provide a driver to get around
the BIOS limit.