MOTOROLA
Chapter 2. Signal Descriptions
2-31
2.2.4.14 Row Address Strobe (RAS[0–7])—Output
The eight row address strobe (RAS[0–7]) signals are outputs on the MPC106. Following
are the state meaning and timing comments for the RAS
n
output signals.
State Meaning
Asserted—Indicates that the memory row address is valid and selects
one of the rows in the selected bank.
Negated—Indicates DRAM precharge period.
Timing Comments
Assertion—The MPC106 asserts the RAS
n
signal to begin a
memory cycle. All other memory interface signal timings are
referenced to RAS
n
.
2.2.4.15 ROM Bank 0 Select (RCS0)—Output
The ROM bank 0 select (RCS0) signal is an output on the MPC106. Following are the state
meaning and timing comments for the RCS0 output signal.
State Meaning
Asserted—Selects ROM bank 0 for a read access or Flash bank 0 for
a read or write access.
Negated—Deselects bank 0, indicating no pending memory access
to ROM/Flash.
Timing Comments
Assertion—The MPC106 asserts RCS0 at the start of a ROM/Flash
access cycle.
2.2.4.16 ROM Bank 1 Select (RCS1)—Output
The ROM bank 1 select (RCS1) signal is an output on the MPC106. Following are the state
meaning and timing comments for the RCS1 output signal.
State Meaning
Asserted—Selects ROM bank 1 for a read access or Flash bank 1 for
a read or write access.
Negated—Deselects bank 1, indicating no pending memory access
to ROM/Flash.
Timing Comments
Assertion—The MPC106 asserts RCS1 at the start of a ROM/Flash
access cycle.
2.2.4.17 Real Time Clock (RTC)—Input
The real time clock (RTC) signal is an input on the MPC106. Following are the state
meaning and timing comments for the RTC input signal.
State Meaning
Asserted/Negated—RTC is an external clock source for the memory
refresh logic when the MPC106 is in the suspend power-saving
mode.
Timing Comments
Assertion—The maximum period of RTC is 1/4 of the refresh
interval of the DRAM. For example, the minimum frequency for
RTC when using DRAMs with a 125
μ
s refresh interval would be
32 kHz.