Quatech DS-200/300 user manual Interrupt Status Register contents Quatech Inc

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6.2 Interrupt Status Register

The DS-200/300 is equipped with an Interrupt Status Register (ISR) which can be used to simplify the servicing of shared interrupts. This register is located at [base address+7] along with the Options Register. Like the OR, the SP jumper must be removed to access the ISR. To further indicate an access to this register, the DLAB bit in the LCR of the UART must be set to 0. The ISR is read-only.

When a hardware interrupt occurs, reading the ISR will return the interrupt status of both ports on the DS-200/300, as shown in Figure 14. Individual bits are cleared as the interrupting ports are serviced. The interrupt service routine must ensure that the ISR reads zero before exiting, or the DS-200/300 will be unable to signal subsequent interrupts.

BIT

DESCRIPTION

 

 

7 (MSB)

0 (not used)

 

 

6

0 (not used)

 

 

5

0 (not used)

4

0 (not used)

 

 

3

0 (not used)

 

 

2

0 (not used)

 

 

1

Serial 1 --- 1 if interrupt pending

 

 

0

Serial 0 --- 1 if interrupt pending

Figure 14 --- Interrupt Status Register contents

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Contents DS-200/300 Page Warranty Information DS-200/300Quatech Inc Iii Table of Contents General Information This Page Intentionally Left Blank Installation Photo of DS-200/300 Quatech Inc Windows 95 Configuration Using the Add New Hardware WizardQuatech Inc Viewing and Changing Resources with Device Manager Page Page Setting the address Addressing PortsSerial 0 uses SW1 and SW2 Serial 1 uses SW3 and SW4 Enabling or disabling ports Recommended addresses for serial portsData Rate Multiplier Data Rate Multiplier Jumper BlockOptions Register Options Register bit definitions This Page Intentionally Left Blank Interrupt Level IRQ Interrupt level IRQ selection Quatech IncInterrupt Sharing Interrupt Status Register contents Quatech Inc Interrupt Status RegisterThis Page Intentionally Left Blank Output Configuration Jumper/Channel/Function correspondenceRTS/CTS handshake RclkXclk AUXIN/AUXOUT Loopback Xclk selection on J5, J7Half Duplex/Full Duplex selection J6/J8 J6 = Serial0 J8 = Serial1Factory Default Configuration of DS-200/300 Output control block diagramTermination Resistors RS-422/485 Peripheral ConnectionDS-200/300 connector definitions for RS-422/485 This Page Intentionally Left Blank Specifications Baud RatesQuatech Inc Troubleshooting Computer will not boot upPage DS-200/300 Revision March