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Vancouver Design Center
S1D13504 Interfacing to the NEC VR4102 Microprocessor
X19A-G-007-07 Issue Date: 01/02/02
4.3 NEC VR4102 Configuration
The NEC VR4102 provides the internal address decoding necessary to map to an external
LCD controller. Physical address 0A00 0000h to 0AFF FFFFh (16M bytes) is reserved for
an external LCD controller.
The S1D13504 supports up to 2M bytes of display buffer. The NEC VR4102 address line
A21 is used to select between the S1D13504 display buffer and internal register set.
The VR4102 uses a read, write and system high-byte enable to interface to an external
LCD controller. The S1D13504 uses low and high byte read and write strobes and therefore
minimal glue logic is necessary.
Table 4-2: NEC/S1D13504 Truth Table
NEC Signals Cycle S1D13504 Signals
SHB# RD# WR# A0
10 1 0
8-bit even address
Read
RD0# = low
RD1# = high
10 1 1
8-bit odd address
Read
RD0# = high
RD1# - low
0 0 1 x 16-bit Read RD0# = low
RD1# - low
11 0 0
8-bit even address
Write
WR0# = low
WR1# = high
11 0 1
8-bit odd address
Write
WR0# = high
WR1# = low
0 1 0 x 16-bit Write WR0# = low
WR1# = low