6. System Interface Operations

6.24 Support for Hardware Emulation

When using the R10000 processor in hardware emulation, it is desirable to operate the System interface at a relative low frequency (typically 1 MHz or below). Since the R10000 processor contains dynamic circuitry, an external agent cannot simply provide low frequency SysClk, so a SysCyc* input to the processor allows an external agent to define a virtual system clock, and yet supply a SysClk within the acceptable operating range. The assertion of SysCyc* in a particular SysClk cycle creates a virtual system clock pulse four SysClk cycles later. SysCyc* may be asserted aperiodically.

In a normal system environment, the SysCyc* input should be permanently asserted.

Figure 6-29 depicts the use of SysCyc* to create a virtual SysClk of one-third the normal SysClk frequency.

Figure 6-29 Hardware Emulation Protocol

Copyright 1995, MIPS Technologies, Inc. -- 29 JAN 96

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