Host Controller Data Manual

4–8

4.7 Configuration ROM Header Register

The configuration ROM header register externally maps to the first quadlet of the 1394 configuration ROM, offset

FFFF F000 0400h. See Table 4–6 for a complete description of the register contents.

Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16

Name Configuration ROM header

Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W

Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Name Configuration ROM header

Type R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W

Default X X X X X X X X X X X X X X X X

Type: Read/Write

Offset: 18h

Default: 0000 XXXXh

Table 4–6. Configuration ROM Header Register Description

BIT FIELD NAME TYPE DESCRIPTION

31–24 info_length R/W

IEEE 1394 bus management field. Must be valid when bit 17 (linkEnable) of the host controller control

23–16 crc_length R/W

IEEE 1394 bus management field. Must be valid when bit 17 (linkEnable) of the host controller control

15–0 rom_crc_value R/W

IEEE 1394 bus management field. Must be valid at any time bit 17 (linkEnable) of the host controller

control register (OHCI offset 50h/54h, see Section 4.16) is set. The reset value is undefined if no serial

ROM is present. If a serial ROM is present, then this field is loaded from the serial ROM.

4.8 Bus Identification Register

The bus identification register externally maps to the first quadlet in the Bus_Info_Block, and contains the constant

3133 3934h, which is the ASCII value of 1394.

Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16

Name Bus identification

Type R R R R R R R R R R R R R R R R

Default 0 0 1 1 0 0 0 1 0 0 1 1 0 0 1 1

Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Name Bus identification

Type R R R R R R R R R R R R R R R R

Default 0 0 1 1 1 0 0 1 0 0 1 1 0 1 0 0

Type: Read-only

Offset: 1Ch

Default: 3133 3934h