spd6722qcce Intel Corporation, spd6722qcce Datasheet - Page 37

• Manufacturer Part Number: spd6722qcce
• Description: Isa-to-pc-card Pcmcia Controllers
• Manufacturer: Intel Corporation

Datasheet
Figure 8. Indexed 8-Bit Register Structure
Figure 9. Indexed 8-Bit Register Example
The following code segment demonstrates use
of an indexed 8-bit register:
The Index register (see
registers the CPU will access next. The value in the Index register is called the Register Index.
This number specifies a unique internal register. The Data register is used by the CPU to read and
write the internal register specified by the Index register.
Double-Indexed Registers
The PD67XX has Extension registers that add to the functionality of the 82365SL-compatible
register set. Within the Extension registers is an Extended Index register and Extended Data
register that provide access to more registers. The registers accessed through Extended Index and
Extended Data are thus double indexed. The example below shows how to access the Extension
Control 1 register, one of the double-indexed registers.
;Write to Extension Control 1 register example
;Constants section
;Code section
Extended_Index
Index_Reg
Ext_Cntrl_1
PD67XX_Index
mov
mov
mov
mov dx, 3E0h
mov ah, 3Ch
mov al, 02h
out dx, ax
High Byte
Internal Registers
dx, PD67XX_Index
al, Extended_Index
ah, Ext_Cntrl_1
3E1h
Data
“Operation Registers” on page
I/O Addresses
EQU 2Eh
EQU 2Fh
EQU 03h
EQU 3E0h
FFh
FEh
•
•
•
02h
01h
00h
ISA-to-PC-Card (PCMCIA) Controllers — PD6710/’22
Register
Indexes
Index
3E0h
AH
Internal Registers
Low Byte
3E1h
3Ch
3Ch
41) is used to specify which of the internal
I/O Addresses
02h
Register
Indexes
3E0h
02h
AL
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