UPD784020 Datasheet, PDF (75/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCOMPUTER

mPD784020, 784021
Timing Waveform for Refresh
(1) Random read/write cycle
tRC
ASTB
WR
tRC
tRC
tRC
tRC
RD
(2) When a refresh is performed simultaneously with a memory access
ASTB
RD, WR
REFRQ
(3) Refresh after reading
tDSTRFQ
tWRFQL
tDRFQST
tWRFQH
ASTB
RD
REFRQ
(4) Refresh after writing
ASTB
WR
REFRQ
tDRRFQ
tDRFQST
tWRFQL
tDWRFQ
tDRFQST
tWRFQL
75