HD6433044 Hitachi Semiconductor, HD6433044 Datasheet - Page 275

• Manufacturer Part Number: HD6433044
• Description: (HD64 Series) Hitachi Single-Chip Microcomputer
• Manufacturer: Hitachi Semiconductor

9.7 Port 6
9.7.1 Overview
Port 6 is a 7-bit input/output port that is also used for input and output of bus control signals
(LWR, HWR, RD, AS, BACK, BREQ, and WAIT). When DRAM is connected to area 3, LWR,
HWR, and RD also function as LW, UW, and CAS, or LCAS, UCAS, and WE, respectively. For
details see section 7, Refresh Controller.
Figure 9-6 shows the pin configuration of port 6. In modes 1 to 6 (expanded modes) the pin
functions are LWR, HWR, RD, AS, P6
the method of selecting the pin states. In mode 7 (single-chip mode) port 6 is a generic
input/output port.
Pins in port 6 can drive one TTL load and a 30-pF capacitive load. They can also drive a
darlington transistor pair.
9.7.2 Register Descriptions
Table 9-10 summarizes the registers of port 6.
Table 9-10 Port 6 Registers
Address*
H'FFC9
H'FFCB
Note: * Lower 16 bits of the address.
Port 6
Name
Port 6 data direction register
Port 6 data register
Port 6 pins
P6 /
P6 /
P6 /
P6 /
P6 /
P6 /
P6 /
6
5
4
3
2
1
0
LWR
HWR
RD
AS
BACK
BREQ
WAIT
Figure 9-6 Port 6 Pin Configuration
Modes 1 to 6
(expanded modes)
P6
P6
P6
2
/BACK, P6
2
1
0
(input/output)/
(input/output)/
(input/output)/
Abbreviation
P6DDR
P6DR
262
1
/BREQ, and P6
LWR
HWR
RD
AS
BACK
BREQ
WAIT
R/W
W
R/W
(output)
(output)
(output)
(output)
(output)
(input)
(input)
0
/WAIT. See table 9-11 for
Mode 1 to 5
H’F8
H’80
Mode 7
(single-chip mode)
P6
P6
P6
P6
P6
P6
P6
Initial Value
6
5
4
3
2
1
0
(input/output)
(input/output)
(input/output)
(input/output)
(input/output)
(input/output)
(input/output)
Mode 6, 7
H'80
H'80