Compaq EV68A specifications Internal Processor Registers

5

Internal Processor Registers

This chapter describes 21264/EV68A internal processor registers (IPRs). They are sep- arated into the following circuit logic groups: Ebox, Ibox, Mbox, and Cbox.

The gray areas in register figures indicate reserved fields. Bit ranges that are coupled with the field name specify those bits in that named field that are included in the IPR. For example, in Figure 5–2,the field named COUNTER[31:4] contains bits 31 through 4 of the COUNTER field from Section 5.1.1. The bit range of COUNTER[31:4] in the IPR is also listed in the column Extent in Table 5–2.In many cases, such as this one, the bit ranges correspond. However, the bit range of the named field need not always corre- spond to the Extent in the IPR. For example, in Figure 5–14,the field VA[47:13] resides in IPR IVA_FORM[37:3] under the stated conditions.

The register contents after initialization are listed in Section 7.8.

Table 5–1lists the 21264/EV68A internal processor registers.

Table 5–1 Internal Processor Registers

				MT/MF	Latency
			Score-	Issued	for
		Index	Board	from Ebox	MFPR
Register Name	Mnemonic	(Binary)	Bit	Access Pipe	(Cycles)

Ebox IPRs

Cycle counter	CC	1100 0000	5	RW	1L	1
Cycle counter control	CC_CTL	1100 0001	5	W0	1L	—
Virtual address	VA	1100 0010	4, 5, 6, 7	RO	1L	1
Virtual address control	VA_CTL	1100 0100	5	WO	1L	—
Virtual address format	VA_FORM	1100 0011	4, 5, 6, 7	RO	1L	1
Ibox IPRs
ITB tag array write	ITB_TAG	0000 0000	6	WO	0L	—
ITB PTE array write	ITB_PTE	0000 0001	4, 0	WO	0L	—
ITB invalidate all process (ASM=0)	ITB_IAP	0000 0010	4	WO	0L	—
ITB invalidate all	ITB_IA	0000 0011	4	WO	0L	—
ITB invalidate single	ITB_IS	0000 0100	4, 6	WO	0L	—
ProfileMePC	PMPC	0000 0101	—	RO	—	—
Exception address	EXC_ADDR	0000 0110	—	RO	0L	3

21264/EV68A Hardware Reference Manual Internal Processor Registers 5–1