User guide

W78C801
- 14 -
Data Read Cycle
PARAMETER SYMBOL MIN. TYP. MAX. UNIT NOTES
ALE Low to RD Low
T
DAR
3 TCP -∆
-
3 TCP +∆
nS 1, 2
RD Low to Data Valid
T
DDA --4 TCP nS 1
Data Hold from RD High
T
DDH 0-2 TCP nS
Data Float from RD High
T
DDZ 0-2 TCP nS
RD Pulse Width
T
DRD
6 TCP -∆
6 T
CP -nS2
Notes:
1. Data memory access time is 8 T
CP.
2. "∆" (due to buffer driving delay and wire loading) is 20 nS.
Data Write Cycle
PARAMETER SYMBOL MIN. TYP. MAX. UNIT
ALE Low to WR Low
T
DAW
3 TCP -∆
-
3 TCP +∆
nS
Data Valid to WR Low
T
DAD
1 TCP -∆
--nS
Data Hold from WR High
T
DWD
1 TCP -∆
--nS
WR Pulse Width
T
DWR
6 TCP -∆
6 T
CP -nS
Note: "∆" (due to buffer driving delay and wire loading) is 20 nS.
Port Access Cycle
PARAMETER SYMBOL MIN. TYP. MAX. UNIT
Port Input Setup to ALE Low TPDS 1 TCP --nS
Port Input Hold from ALE Low TPDH 0--nS
Port Output to ALE TPDA 1 TCP --nS
Note: Ports are read during S5P2, and output data becomes available at the end of S6P2. The timing data are referenced to
ALE, since it provides a convenient reference.