upd7566a Renesas Electronics Corporation., upd7566a Datasheet - Page 17

• Manufacturer Part Number: upd7566a
• Description: 4-bit Single-chip Microcomputer
• Manufacturer: Renesas Electronics Corporation.

2.5
area. The data memory is also used in pairs with the accumulator, making it possible to process 8-bit data.
the SP by TAMSP instruction. After that, the stack area is automatically accessed by call and return instructions.
as illustrated below.
The data memory is static RAM configured of 64 words by 4 bits, and is used to store various data and as a stack
The data memory can be addressed in the following three addressing modes:
Any space in the data memory can be used as stack. The boundary of the stack is determined by initializing
When a call instruction is executed, the contents of the PC and program status word (PSW) are stored in stack,
When a return instruction has been executed, the PC contents are restored, but the PSW contents are not.
The data memory contents can be retained on a low supply voltage in the STOP mode.
DATA MEMORY (RAM) ...... 64 WORDS X 4 BITS
•
•
•
Direct: In this mode, the data memory is directly addressed by the immediate data for an instruction.
Register indirect: The data memory is indirectly addressed by the contents of pair register HL (including
autoincrement and autodecrement).
Stack: The data memory is indirectly addressed by the contents of the stack pointer (SP).
(63) 3FH
(0) 00H
SP - 4
SP - 3
SP - 2
SP - 1
Fig. 2-6 Data Memory Map
3
0
64 words x 4 bits
PC3 - PC0
PC7 - PC4
Stack area
0
PSW
PC9
Note
PC8
0
Note Bit 1 of PSW is always 0.
PD7566A, 7566A(A)
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