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Epson Research and Development
Vancouver Design Center
S1D13505
Hardware Functional Specification
X23A-A-001-14
Issue Date: 01/02/02
8.2.2 Memory Configuration Registers
bits 6-4
DRAM Refresh Rate Select Bits [2:0]
These bits specify the divisor used to generate the DRAM refresh rate from the input clock (CLKI).
bit 2
WE# Control
When this bit = 1, 2-WE# DRAM is selected.
When this bit = 0, 2-CAS# DRAM is selected.
bit 0
Memory Type
When this bit = 1, FPM-DRAM is selected.
When this bit = 0, EDO-DRAM is selected.
This bit should be changed only when there are no read/write DRAM cycles. This condition occurs
when all of the following are true: the Display FIFO is disabled (REG[23h] bit 7 = 1), and the Half
Frame Buffer is disabled (REG[1Bh] bit 0 = 1), and the Ink/Cursor is inactive
(Reg[27h] bits 7-6 = 00). This condition also occurs when the CRT and LCD enable bits (Reg[0Dh]
bits 1-0) have remained 0 since chip reset. For further programming information, see S1D13505
Programming Notes and Examples, document number X23A-G-003-xx.
Memory Configuration Register
REG[01h]
RW
n/a
Refresh Rate
Bit 2
Refresh Rate
Bit 1
Refresh Rate
Bit 0
n/a
WE# Control
n/a
Memory Type
Table 8-2: DRAM Refresh Rate Selection
DRAM Refresh Rate
Select Bits [2:0]
CLKI Frequency
Divisor
Example Refresh Rate
for CLKI = 33MHz
Example period for
256 refresh cycles at
CLKI = 33MHz
000
64
520 kHz
0.5 ms
001
128
260 kHz
1 ms
010
256
130 kHz
2 ms
011
512
65 kHz
4 ms
100
1024
33 kHz
8 ms
101
2048
16 kHz
16 ms
110
4096
8 kHz
32 ms
111
8192
4 kHz
64 ms