HD6432621 Hitachi, HD6432621 Datasheet - Page 200

• Manufacturer Part Number: HD6432621
• Description: (HD64F262x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

7.4.3
Table 7-4 shows the data buses used and valid strobes for the access spaces.
In a read, the RD signal is valid without discrimination between the upper and lower halves of the
data bus.
In a write, the HWR signal is valid for the upper half of the data bus, and the LWR signal for the
lower half.
Table 7-4
Area
8-bit access
space
16-bit access Byte
space
Notes: Hi-Z: High impedance.
156
Invalid: Input state; input value is ignored.
Valid Strobes
Data Buses Used and Valid Strobes
Access
Size
Byte
Word
Read/
Write
Read
Write
Read
Write
Read
Write
Address
—
—
Even
Odd
Even
Odd
—
—
Valid
Strobe
RD
HWR
RD
HWR
LWR
RD
HWR, LWR Valid
Upper Data Bus
(D15 to D8)
Valid
Valid
Invalid
Valid
Hi-Z
Valid
Lower data bus
(D7 to D0)
Invalid
Hi-Z
Invalid
Valid
Hi-Z
Valid
Valid
Valid