GMS30004 Datasheet, PDF (22/158 Pages) Hynix Semiconductor – 4-BIT SINGLE CHIP MICROCOMPUTERS

Chapter 2. Architecture
Data memory (RAM)
Ø Ø Up to 32 nibbles (16 words 2pages 4bits) is incorporated for storing data.
The whole data memory area is indirectly specified by a data pointer (X,Y). Page
number is specified by zero bit of X register, and words in the page by 4 bits in
Y-register. Data memory is composed in 16 nibbles/page. Figure 2.2 shows the
configuration.
D0 D9 R0 R3 REMOUT
Output port
Data memory page (0~1)
01
23
Page 0
Page 1
15
4 A0~A3
Y-register (Y)
01
X-register (X)
4
2
Fig 2-2 Composition of Data Memory
X-register (X)
X-register is consist of 2bit, X0 is a data pointer of page in the RAM, X1 is only
used for selecting of D8~D9 with value of Y-register
X1=0
X1=1
Y=0
D0
D8
Y=1
D1
D9
Table 2-1 Mapping table between X and Y register
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