Texas Memory Systems manual Appendix C XP-15 Hardware Control and Status Registers, Reserved

Appendix C – XP-15 Hardware Control and Status Registers

The XP-15 is a custom hardware adapter designed to provide processing power to a host computer (DEC Alpha, Intel PC, etc..). The XP-15's data bus is 32-bits or 64-bits wide (depending on the host PCI slot).

The following tables describe the XP-15's hardware control registers. Each register is classified as read only, write only, or read/write. The least significant bit of each register is always tied to the least significant bit of the PCI bus. Any unspecified bits should be masked in software after they are read, even though they will not be used.

As defined by the PCI Local Bus Specification Rev. 2.2, the XP-15 has one Base Address Regions. All registers are defined as offsets into this one address region. Bit-level definitions of all registers, including rules for their use, appear in the following tables and paragraphs.

				XP-15 Hardware Registers
		Register Name				Base	Offset	Type	Size
						Address
						Region
	Control-Status Register (CSR)					0	0h	R/W	32 bits
	Low PCI SN command address register[31..0]					0	4h	R/W	32 bits
	High PCI SN command address register[63..32]					0	8h	R/W	32 bits
	Low PCI SN response address register[31..0]					0	Ch	R/W	32 bits
	High PCI SN response address register[63..32]					0	10h	R/W	32 bits
			Control-Status Register (32 bits, R/W)
	Bit #	Name	Type		Description
	31-16	RESERVED	N/A		These bits are reserved.
	15	Reset	WO		Softreset, puts the XP-15 in the power-up state.
	14	Start	WO		Informs XP-15 to start processing SN command.
	13	END	WO		Indicates host is big Endian.
	12-10	RESERVED	N/A		These bits are reserved.
	9	64	WO		Indicates XP-15 is in a 64-bit PCI slot
	8	RESERVED	N/A		This bit is reserved.
	7	DMADONE	RO		Indicates the DMA is finished.
	6	STOP	RO		Indicates the STOP bit has been encountered.
	5	PAUSE	RO		Indicates the XP-15 is paused.
	4	ERR	RO		Indicates the XP-15 has received an SN checksum error.
PCI200 User Guide			Texas Memory Systems, Inc. (8/6/01)							C-1