GMS36 Datasheet, PDF (36/109 Pages) Hynix Semiconductor – 4-BIT SINGLE CHIP MICROCOMPUTERS

Chapter 4. FUNCTIONAL DESCRIPTION
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)
0
1
2
3
Page 0
Page 1
4 a₀~a₃
Y-register (Y)
15
01
X-register (X)
Fig 4-2 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 4-1 Mapping table between X and Y register
4-3