Dram Refresh Controller - Epson Stylus Pro Service Manual

Stylus Pro Service Manual

2.3.2.7 DRAM Refresh Controller

The CPU is equipped with a refresh controller in its internal controller. This CPU controller can contact the
16-bit length IC5 DRAM, which is a 2 CAS type. The following table lists the junction method between the
H8 CPU and the 2 CAS DRAM.
Table 2-10. Junction Method (CPU - 2 CAS DRAM)
This method of the DRAM refresh is only used for the CAS-before-RAS cycle method. The following figure
shows the timing of each cycle.
UC A S
L C A S
R A S
W R
A S
(Read / Write Cycle)
Figure 2-27. Junction Method (CPU - DRAM)
Rev.A
CPU
HWR
LWR
CS3
RD
U C A S
L C A S
Read Cycle
Write Cycle
Operating Principles
2 CAS DRAM
UCAS
LCAS
RAS
WR
R A S
W R
A S
(Refresh Cycle)
2-21