	IP19 EAROM Description
	----------------------

The IP19 EAROM contains the R4000 boot-time serial bitstream data
and a number of constants which pertain to features which may change
during the evolution of the Everest system.  This file contains
a description of the EAROM contents.

In the following table, the byte numbers are in decimal.  Hexadecimal
values will be explicitly prefixed with '0x'.

Byte #		Description
------		-------------------------------------------------------------
0-31		These bytes contain the serial bit-stream data which is
		copied into the R4000 when it is reset.  See Chapter 12
		in the NEC VR4000 Microprocessor manual for more information
		on these bits.
		  INITIAL VALUE:  See R4000 manual

32-39		Reserved for future use.  Currently 0.

40-43		Everest Bus Frequency in Hertz, specified as a 4-byte
		unsigned value.  Byte 40 is the LSB, and byte 43 is the MSB.  
		INITIAL VALUE: 0x02faf080  (50,000,000)

44		Status of the Piggyback Read Enable feature.  When this byte
		is set to 1, the PROM will turn on Piggyback Reads.
		INITIAL VALUE: 0x1

45		Size of the secondary cache in megabytes.  The PROM
		uses this value to size and test the secondary cache, and
		the CC chip uses it to govern Bus tag spans.
		INITIAL VALUE: 0x1 (1 megabyte)

46		IW Trigger value.  The contents of this byte is used
		directly as the value for the CC chip's IW_TRIG register.
		INITIAL VALUE: 0x3

47		RR Trigger value.  The contents of this byte is used
		directly as the value for the CC chip's RR_TRIG register. 
		INITIAL VALUE: 0x0

48-51		The external master clock frequency (in Hz) for the 
		R4000.  These four bytes contain an unsigned integral
		value.  Byte 48 contains the LSB, and Byte 51 contains
		the MSB.
		INITIAL VALUE: 0x02faf080 (50,000,000)

52-55		The Real Time Clock frequency in Hz, specified as a
		4-byte unsigned integral value.  Byte 52 contains
		the LSB, and byte 55 contains the MSB.
		INITIAL VALUE: 0x02faf080 (50,000,000)

56-57		The number of times the EAROM has been written.  Because
		EAROM's can only be written a finite number of times before
		they begin to fail.  Every time the EAROM is written this
		value is updated, and when it goes above some critical
		value the PROM will display a warning. 
		INITIAL VALUE: 0x1	
