US 5,475,846 AGranted

Apparatus for processing PCMCIA interrupt requests

AssigneeDatabook, Inc.

InventorTerrill M. Moore

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Abstract

An apparatus to permit the sharing of interrupts between resident devices and removable PCMCIA peripherals overcomes a deficiency in the PCMCIA standards. By permitting interrupt sharing, the apparatus allows standard application software, which assumes the interrupt sharing capability of standard built-in peripherals to operate with PCMCIA cards. The invention is particularly suited to serial communication ports, where interrupts are routinely shared. An interface component 20 is coupled to an interrupt controller 12. A serial port COM1 is connected to a host interrupt IRQ4, which is shared by a PCMCIA card serial port 22, configured as COM3, through the interface controller 20. Through the use of an open-drain output and a conversion in the controller 20 of the level mode interrupt from the PCMCIA card to a low-going pulse of sufficient voltage swing and duration, the host interrupt is shared between the permanently installed COM1 and the removable COM3 serial ports.

Claims9

Dependent claims

A computer system comprising:

a microprocessor;
an interrupt controller coupled to said microprocessor, said interrupt controller having at least a first interrupt request input;
a pull-up resistor coupled between a power source and said first interrupt request input;
first serial port means having a first output coupled to said first interrupt request input and a first peripheral port input coupled to a first peripheral device, said first serial port means when enabled outputting a first non-interrupt state on said first output until a first interrupt request is received from said first peripheral device and then outputting a first interrupt state on said first output and said first serial port means when disabled outputting a first high impedance state on said first output;
and
second serial port means having a second output coupled to an interface component and a second peripheral port input coupled to a second peripheral device, said second serial port means when enabled outputting a second non-interrupt state on said second output until a second interrupt request is received from said second peripheral device and then outputting a second interrupt state on said second output and said second serial port when disabled outputting a second high impedance state on said second output;
and
said interface component having an interface output coupled to said first interrupt request input, said interface component outputting a third high impedance state when said interface output receives said second non-interrupt state or said second high impedance state and outputting a third interrupt state when said interface component receives a second interrupt state and said first serial port is disabled.

5 more elements

Dependencies are inferred from the claim text.