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CPU386 Timing Data Hardware Platform

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10.2: Hardware Platform

All times reported except for the maximum period interrupts are disabled by RTEMS were measured using a Force Computers CPU386 board. The CPU386 is a 16 Mhz board with zero wait state dynamic memory and an i80387 numeric coprocessor. One of the count-down timers provided by a Motorola MC68901 was used to measure elapsed time with one microsecond resolution. All sources of hardware interrupts are disabled, although the interrupt level of the i386 allows all interrupts.

The maximum period interrupts are disabled was measured by summing the number of CPU cycles required by each assembly language instruction executed while interrupts were disabled. Zero wait state memory was assumed. The total CPU cycles executed with interrupts disabled, including the instructions to disable and enable interrupts, was divided by 16 to simulate a i386 executing at 16 Mhz.


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