Quatech DS-200/300 user manual Interrupt Sharing

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6.1 Interrupt Sharing

Both ports on the DS-200/300 can share the same interrupt level or they can share their interrupt with another Quatech adapter supporting sharable interrupts. Jumper J2 can be used to connect the UART generated interrupt directly to the selected IRQ or to enable the interrupt sharing circuit. In either case, the software driving the serial ports must determine which port or ports are requesting service when an interrupt is generated. To maintain 100% ISA bus compatibility, J2 should be set in the non-sharable mode.

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J2 --- Sharable interrupt

jumper block configurations

Figure 13--- Sharable interrupt selection

The DS-200/300 signals a hardware interrupt when any port requires service. The interrupt signal is maintained until no port requires service. Because the ISA bus is edge-sensitive, this behavior forces the interrupt service routine to ensure that all ports are checked before exiting. A way to do this is to poll each port until an interrupting port is found. After servicing the port, all ports should be checked again. If any interrupting port is left unserviced the DS-200/300 will be unable to signal any further interrupts.

DS-200/300 User's Manual

6-2

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Contents DS-200/300 Page DS-200/300 Warranty InformationQuatech Inc Iii Table of Contents General Information This Page Intentionally Left Blank Installation Photo of DS-200/300 Quatech Inc Using the Add New Hardware Wizard Windows 95 ConfigurationQuatech Inc Viewing and Changing Resources with Device Manager Page Page Addressing Ports Setting the addressSerial 0 uses SW1 and SW2 Serial 1 uses SW3 and SW4 Recommended addresses for serial ports Enabling or disabling portsOptions Register Data Rate MultiplierData Rate Multiplier Jumper Block Options Register bit definitions This Page Intentionally Left Blank Interrupt level IRQ selection Quatech Inc Interrupt Level IRQInterrupt Sharing Interrupt Status Register Interrupt Status Register contents Quatech IncThis Page Intentionally Left Blank Jumper/Channel/Function correspondence Output ConfigurationXclk RTS/CTS handshakeRclk Xclk selection on J5, J7 AUXIN/AUXOUT LoopbackJ6/J8 J6 = Serial0 J8 = Serial1 Half Duplex/Full Duplex selectionOutput control block diagram Factory Default Configuration of DS-200/300RS-422/485 Peripheral Connection Termination ResistorsDS-200/300 connector definitions for RS-422/485 This Page Intentionally Left Blank Baud Rates SpecificationsQuatech Inc Computer will not boot up TroubleshootingPage DS-200/300 Revision March