ISA-to-PC-Card (PCMCIA) Controllers
—
PD6710/
’
22
Datasheet
81
10.7.4
External Data (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 PC Card (PCMCIA) controller
product line, the Socket A
External Data
register should only be used as a
write
port and not as a
read
port. Also for compatibility, only the lower nibble of
External Data
should be accessed and
the upper nibble should be ignored.
Refer to
“
Using GPSTB Pins for External Port Control (PD6722 only)
”
on page 91
for more
information on the use of the
External Data
register.
E0h
13 clocks = 520 ns
10h
14 clocks = 560 ns
90h
15 clocks = 600 ns
50h
16 clocks = 640 ns
D0h
17 clocks = 680 ns
30h
18 clocks = 720 ns
B0h
19 clocks = 760 ns
Register Name:
External Data
Index:
2Fh only
Extended Index:
0Ah
Register Per:
socket
Register Compatibility Type:
ext.
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
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 14. Maximum DMA Acknowledge Delay Register Values
(Sheet 2 of 2)
Register Value
Maximum DMA Acknowledge Delay
(25-MHz internal clock and default Setup timing)
Table 15. 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
produce the value written to the latch.
1
1
Reserved