
CL-PD6710/’22
ISA–to–PC-Card Host Adapters
May 1997
69
PRELIMINARY DATA SHEET v3.1
EXTENSION REGISTERS
9.7.4
External Data (CL-PD6722 only, Socket A, Index 2Fh)
Bits 7:0 — External Data
This register is updated and accessed according to the setting of bits 3 and 4 of the Socket A
Extension Control 2
register (Index 2Fh, Extended Index 0Bh).
NOTE:
For software compatibility of external data access accross the Cirrus Logic PC Card host adapter product
line, the Socket A
External Data
register should only be used as a writeport and not as a readport. Also
for compatibility, only the lower nibble of
External Data
should be accessed and the upper nibble should be
ignored.
Refer to
Chapter 12
for more information on the use of the
External Data
register.
Register Name:
External Data
Index:
2Fh only
Bit
7
Extended Index:
0Ah
Bit
4
Register Per: socket
Register Compatibility Type: ext.
Bit
1
Bit
6
Bit
5
Bit
3
Bit
2
Bit
0
External Data
7
External Data
6
External Data
5
External Data
4
External Data
3
External Data
2
External Data
1
External Data
0
RW:0
RW:0
RW:0
RW:0
RW:0
RW:0
RW:0
RW:0
Table 9-2.
Functions of Socket A External Data Register
Socket A Extension Control 2
Function of Socket A External Data Register
Bit 4: GPSTB
on IOW*
Bit 3: GPSTB
on IOR*
0
0
Scratchpad
0
1
External read port: A_GPSTB is a read buffer enable for external data on
SD[15:8]
1
0
External write port: A_GPSTB is a write latch enable for SD[15:8] to get
latched to an external register. Reads of Socket A External Data register pro-
duce the value written to the latch.
1
1
Reserved