Z8018x
Family MPU User Manual
UM005004-0918
89
Refresh Control And RESET
After RESET, based on the initialized value of RCR, refresh cycles occur
with an interval of ten clock cycles and are three clock cycles in duration.
Dynamic Ram Refresh Operation Notes
1. Refresh Cycle insertion is stopped when the CPU is in the following
states:
–
During RESET
–
When the bus is released in response to BUSREQ
–
During SLEEP mode
–
During Wait States
2. Refresh cycles are suppressed when the bus is released in response to
BUSREQ. However, the refresh timer continues to operate. Thus, the
time at which the first refresh cycle occurs after the Z8X180 re-
acquires the bus depends on the refresh timer and has no timing
relationship with the bus exchange.
Table 11. DRAM Refresh Intervals
CYC1 CYC0
Insertion
Interval
Time Interval
10 MHz
8 MHz
6 MHz
4 MHz
2.5 MHz
0
0
10 states
(1.0
μ
s)*
(1.25
μ
s)*
1.66
μ
s
2.5
μ
s
4.0
μ
s
0
1
20 states
(2.0
μ
s)*
(2.5
μ
s)*
3.3
μ
s
5.0
μ
s
8.0
μ
s
1
0
40 states
(4.0
μ
s)*
(5.0
μ
s)*
6.8
μ
s
10.0
μ
s
16.0
μ
s
1
1
80 states
(8.0
μ
s)*
(10.0
μ
s)*
13.3
μ
s
20.0
μ
s
32.0
μ
s
* Calculated interval
Summary of Contents for Z8018 Series
Page 1: ...www zilog com Z8018x Family MPU User Manual UM005004 0918...
Page 206: ...Z8018x Family MPU User Manual 192 UM005004 0918...
Page 220: ...Z8018x Family MPU User Manual 206 UM005004 0918...
Page 250: ...Z8018x Family MPU User Manual 236 UM005004 0918...
Page 260: ...Z8018x Family MPU User Manual 246 UM005004 0918...
Page 300: ...Z8018x Family MPU User Manual 286 UM005004 0918...
Page 306: ...Z8018x Family MPU User Manual 292 UM005004 0918...