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27 subsystem id register – Texas Instruments Dual/Single Socket CardBus and UntraMedia Controller PCI7621 User Manual

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4−17

4.27 Subsystem ID Register

The subsystem ID register, used for system and option card identification purposes, may be required for certain
operating systems. This register is read-only or read/write, depending on the setting of bit 5 (SUBSYSRW) in the
system control register (PCI offset 80h, see Section 4.29). When bit 5 is 0, this register is read/write; when bit 5 is
1, this register is read-only. The default mode is read-only. All bits in this register are reset by GRST only.

If an EEPROM is present, then the subsystem ID and subsystem vendor ID is loaded from the EEPROM after a reset.

Bit

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Name

Subsystem ID

Type

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

Default

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Register:

Subsystem ID

Offset:

42h (Functions 0, 1)

Type:

Read-only, (Read/Write when bit 5 in the system control register is 0)

Default: 0000h

4.28 PC Card 16-Bit I/F Legacy-Mode Base-Address Register

The PCI7x21/PCI7x11 controller supports the index/data scheme of accessing the ExCA registers, which is mapped
by this register. An address written to this register is the address for the index register and the address+1 is the data
address. Using this access method, applications requiring index/data ExCA access can be supported. The base
address can be mapped anywhere in 32-bit I/O space on a word boundary; hence, bit 0 is read-only, returning 1 when
read. As specified in the PCI to PCMCIA CardBus Bridge Register Description specification, this register is shared
by functions 0 and 1. See the ExCA register set description in Section 5 for register offsets. All bits in this register
are reset by GRST only.

Bit

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

Name

PC Card 16-bit I/F legacy-mode base-address

Type

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

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

PC Card 16-bit I/F legacy-mode base-address

Type

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

RW

R

Default

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

Register:

PC Card 16-bit I/F legacy-mode base-address

Offset:

44h (Functions 0, 1)

Type:

Read-only, Read/Write

Default: 0000 0001h