General Information - Quatech DS-200 User Manual

1. General Information

The Quatech, Inc. DS-200/300 provides two RS-422/RS-485 asynchronous
serial communication interfaces for IBM-compatible personal computer
systems using the 16-bit ISA (Industry Standard Architecture) expansion
bus.
The DS-200/300's serial ports are implemented using 16550 or 16750
Universal Asynchronous Receiver/Transmitters (UARTs). The 16550
UARTs enable the DS-200/300 to transmit and receive data at a rate of up
to 230.4 kbaud; the 16750 UARTs enable data rates of up to 921.6 kbaud.
The data rate can be altered either through hardware or software. The
16550 contains a 16-byte hardware buffer that reduces processing
overhead; the 16750 contains a 64-byte hardware buffer. To use the
16550/16750's buffering capabilities, the software must be aware of the
UART's presence. Otherwise, it will act as a 16450 UART. The 16750 is
suggested for heavy multitasking environments and for applications
involving high data rates.
The DS-200/300 uses Quatech's new Enhanced Serial Adapter design.
This allows the user to access higher data rates by either setting a jumper
on the board or by programming a special register. The register also
allows the board to be identified as a Quatech Enhanced Serial Adapter.
This enables specially written software to take advantage of the added
features.
The DS-200/300 is highly flexible with respect to addressing and interrupt
level use. The serial ports are individually addressed and can be placed
anywhere within the range of 0000 hex to FFF8 hex at 0008 hex intervals.
Available interrupt levels include IRQ2 to IRQ7, IRQ10 to IRQ12, IRQ14,
or IRQ15.
Both ports on the DS-200/300 can share one interrupt level or an interrupt
level can be shared with another Quatech adapter that supports interupt
sharing. A special Interrupt Status Register is provided to allow
controlling software to manage the shared interrupt level. The shared
interrupt feature minimizes the system resources consumed by the
adapter.
In order to support the use of the shared interrupt feature and the higher
data rates of the DS-200/300, Quatech has developed device drivers for
several popular operating systems and environments. The sales
department can be contacted for details on current offerings.
DS-200/300 User's Manual 1-1