Rainbow Electronics W78C801 - Manual (Page 14)

W78C801
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Data Read Cycle
PARAMETER SYMBOL MIN. TYP. MAX. UNIT NOTES
ALE Low to RD Low T DAR 3 T CP -
∆ - 3 T CP +
∆ nS 1, 2
RD Low to Data Valid T DDA - - 4 T CP nS 1
Data Hold from RD High T DDH 0 - 2 T CP nS
Data Float from RD High T DDZ 0 - 2 T CP nS
RD Pulse Width T DRD 6 T CP -
∆ 6 T
CP - nS 2
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 T CP -
∆ - 3 T CP +
∆ nS
Data Valid to WR Low T DAD 1 T CP - ∆ - - nS
Data Hold from WR High T DWD 1 T CP -
∆ - - nS
WR Pulse Width T DWR 6 T CP - ∆ 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 T PDS 1 T CP - - nS
Port Input Hold from ALE Low T PDH 0 - - nS
Port Output to ALE T PDA 1 T CP - - 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.