Category : Pascal Source Code
Archive   : INFOS155.ZIP
Filename : PAGE_08.INF

This page gives information on the printer and serial ports, along with
various sound cards.

Up to 3 printer ports will be shown. The ports are found in a special
table in the BIOS data area. The Busy, ACK, Paper out, Selected, I/O
error, and Timed out values are what the printer is reporting. If you set
your printer off-line, and re-display the page, the Selected line should
change.

Up to 4 serial ports will be shown. The port addresses are found in a
special table in the BIOS data area.

The interface between the serial device and the computer is called a UART
(Univeral Asynchronous Receiver/Transmitter.) There are several types
typcially used in a PC. The 8250 is usually found in PC/XT's, and internal
modems. The 16450 typically in AT/386/486's.

A newer type is the 16550. There are several versions. The most common
is the 16550A/16550AN/16550AFN. These versions contain a 16 byte buffer
that lets incoming data build up before the computer must read it.

If a program (such as Desqview) has set the port to 0, then INFOPLUS has
been denied access to it. This is often done to prevent programs from
interfering with each other.

INFOPLUS can detect several sound cards, including the Adlib, Sound
Blaster, and Roland MPU-401.

The Adlib is used by many games, and is cloned by the Sound Blaster. It
offers several sound and rhythm voices for music and games. There is also
a special SOUND.COM driver that offers an interface to play music.
INFOPLUS checks to see if this driver is loaded.

The Sound Blaster, in addition to it's AdLib capabilities, also has a
digital channel and stereo capabilities. The port shown if found is the
one used to access the digital capabilities, and is selectable by a jumper
on the card.

The Roland MPU-401 is actually a MIDI controller.