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S1D13505 Hardware Functional Specification
X23A-A-001-14 Issue Date: 01/02/02
9 Display Buffer
The system addresses the display buffer through the CS#, M/R#, and AB[20:0] input pins. When
CS# = 0 and M/R# = 1, the display buffer is addressed by bits AB[20:0]. See the table below:
The display buffer address space is always 2M bytes. However, the physical display buffer may be
either 512K bytes or 2M bytes – see “Summary of Configuration Options”.
The display buffer can contain an image buffer, one or more Ink/Cursor buffers, and a half-frame
buffer.
A 512K byte display buffer is replicated in the 2M byte address space – see the figure below.
Figure 9-1: Display Buffer Addressing
Table 9-1: S1D13505 Addressing
CS# M/R# Access
00
Register access:
REG[00h] is addressed when AB[5:0] = 0
REG[01h] is addressed when AB[5:0] = 1
REG[n] is addressed when AB[5:0] = n
01
Memory access: the 2M byte display buffer is addressed by
AB[20:0]
1X
S1D13505 not selected
Image Buffer
Ink/Cursor Buffer
Half-Frame Buffer
Image Buffer
Ink/Cursor Buffer
Half-Frame Buffer
Image Buffer
Ink/Cursor Buffer
Half-Frame Buffer
Image Buffer
Ink/Cursor Buffer
Half-Frame Buffer
Image Buffer
Ink/Cursor Buffer
Half-Frame Buffer
512K Byte Buffer 2M Byte BufferAB[20:0]
000000h
07FFFFh
080000h
0FFFFFh
100000h
17FFFFh
180000h
1FFFFFh