Abstract: A dedicated memory area is provided on a microprocessor system for storing a customizable system interrupt service routine, processor state data at the time of interruption and a halt indicator indicating the CPU was interrupted from a halt state. The dedicated memory area is normally not mapped as part of the main memory space, thereby keep it inaccessible to the operating system and applications. An unmaskable system supervisor interrupt having higher priority than all other maskable and unmaskable interrupts is added to the CPU interrupts. The halt state indicator is set by the added interrupt of the CPU is in a halt state at the time of interruption. A RESUME instruction is added to the CPU instructions to provide recovery of the CPU to the state before it was interrupted. The Halt instruction is re-executed by the RESUME instruction if the halt state indicator remains set at the time of restoration.

Abstract: A transparent system interrupt is invoked by the assertion of an electrical signal at an external pin of a microprocessor CPU chip. Upon assertion of this interrupt, the CPU begins program execution in a dedicated RAM area that is inaccessible both to the operating system and all application programs. A set of instructions, which may be unique to the system in which the CPU chip is installed, services the interrupt. Typically, the state of the CPU and associated components in the system immediately prior to assertion of the interrupt will be saved into the dedicated RAM area by the interrupt service routine. Recovery from the interrupt is accomplished upon recognition of an external event that invokes a RESUME instruction causing the CPU and associated components to be restored to exactly the same state that existed prior to the interrupt and in a manner entirely transparent to any program executing at the time of the interrupt.

Abstract: A dedicated memory area is provided on a microprocessor system for storing a customizable system interrupt service routine, and processor state data at the time of interruption. The dedicated memory area is normally not mapped as part of the main memory space, thereby keep it inaccessible to the operating system and applications. An unmaskable system supervisor interrupt having higher priority than all other maskable and unmaskable interrupts is added to the CPU interrupts. The extended memory addressing limits are overridden when the CPU is interrupted by this added interrupt. A RESUME instruction is added to the CPU instructions to provide recovery of the CPU to the state before it was interrupted. The extended memory addressing limits are restored when the CPU is restored by the RESUME instruction.

Abstract: A CPU of a microprocessor system is modified to post an executed write I/O instruction upon completion of writing by the bus unit. A dedicated memory area is provided for storing a customizable system interrupt service routine, program state data at the time of interruption and an I/O trap indicator indicating the CPU was interrupted during execution of an I/O instruction. The dedicated memory area is normally not mapped as part of the main memory space, thereby keep it inaccessible to the operating system and applications. An unmaskable system supervisor interrupt having higher priority than all other maskable and unmaskable interrupts is added to the CPU interrupts. A RESUME instruction is added to the CPU instructions to provide recovery of the CPU to the state before it was interrupted and continued execution including automatic re-execution of an interrupted I/O instruction.

Abstract: A transparent system interrupt is invoked by the assertion of an electrical signal at an external pin of a microprocessor CPU chip. Upon assertion of this interrupt, the CPU begins program execution in a dedicated RAM area that is inaccessible both to the operating system and all application programs. A set of instructions, which may be unique to the system in which the CPU chip is installed, services the interrupt. Typically, the state of the CPU and associated components in the system immediately prior to assertion of the interrupt will be saved into the dedicated RAM area by the interrupt service routine. Recovery from the interrupt is accomplished upon recognition of an external event that invokes a RESUME instruction causing the CPU and associated components to be restored to exactly the same state that existed prior to the interrupt and in a manner entirely transparent to any program executing at the time of the interrupt.