PC87413 datasheet(39/257 Pages) NSC

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3.0 Device Architecture and Configuration (Continued)

Revision 1.2

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3.2.2

Banked Logical Device Registers Structure

Each functional block is associated with a Logical Device Number (LDN). The configuration registers are grouped into banks,

where each bank holds the standard configuration registers of the corresponding logical device. Table 9 shows the LDN val-

ues of the PC8741x functional blocks. Any value not listed is reserved.

Figure 3 shows the structure of the standard configuration register file. The LDN and ServerI/O Configuration registers are

not banked and are accessed by the Index-Data register pair only, as described above. However, the device control and

device configuration registers are duplicated over 10 banks for the 10 logical devices. Therefore, accessing a specific reg-

ister in a specific bank is performed by two-dimensional indexing, where the LDN register selects the bank (or logical device)

and the Index register selects the register within the bank. Accessing the Data register while the Index register holds a value

of 30h or higher actually accesses the configuration registers of the logical device selected by the LDN register and pointed

to by the Index register.

Figure 3. Structure of Standard Conﬁguration Register File

Table 9. Logical Device Number (LDN) Assignments

Write accesses to unimplemented registers (i.e., accessing the Data register while the Index register points to a non-existing

which returns 04h (indicating no DMA channel). The configuration registers are accessible immediately after reset.

LDN

Functional Block

00h

Floppy Disk Controller (FDC)

01h

Parallel Port (PP)

02h

Serial Port 2 (SP2)

03h

Serial Port 1 (SP1)

04h

System Wake-Up Control (SWC)

05h

Keyboard and Mouse Controller (KBC) - Mouse Interface

06h

Keyboard and Mouse Controller (KBC) - Keyboard Interface

07h

General-Purpose I/O (GPIO) Ports

0Fh

X-Bus Extension (PC87416 and PC87417)

10h

Real Time Clock (RTC)

07h

20h

30h

60h

75h

FEh

Logical Device Number Register

ServerI/O Configuration Registers

Logical Device Control Register

Standard Logical Device

Special (Vendor-defined)

Configuration Registers

Banks

2Fh

F0h

Bank Select

63h

74h

70h

71h

Configuration Registers

(One per Logical Device)

Logical Device

PC87413 Datenblatt(PDF) 39 Page - National Semiconductor (TI)

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