ML63611 User’s Manual
Chapter 2 CPU and Memory Spaces
2 – 1
OPTION B (D): 1.5 V (3.0 V), With regulator
circuit for LCD bias
OPTION A (C): 1.5 V (3.0 V), Without regulator
circuit for LCD bias
2. CPU and Memory Spaces
2.1
Overview
The ML63611 is equipped with Oki’s original CPU core nX-4/250.
The instruction set of the nX-4/250 core consists of 407 types of instructions.
The memory space consists of a 16-bit wide program memory space and a 4-bit wide data memory space. A stack
for saving the program counter during a subroutine call or interrupt (call stack) and a stack for saving registers
during a PUSH instruction (register stack) are provided separately from the memory space.
The program memory space is used for program data, ROM table data and melody note data.
In the data memory space, special function registers (SFRs) are located in BANK 0, the LCD display register
(DSPR) in BANK 1, and data RAM in BANKS 2 to 5.
2.2
Registers
The nX-4/250 core processes data mainly with the accumulator and register set.
The register set is a programming model consisting of the HL and XY registers that store data memory addresses,
the current bank register (CBR), the extra bank register (EBR), the RA register that stores program memory
addresses, registers that control program flow, and registers that control flags and memory.
2.2.1 Accumulator (A)
The accumulator (A) is the central register for various arithmetic operations.
At system reset, the accumulator is initialized to “0”. When an interrupt occurs, a “PUSH HL” instruction can be
used if necessary to save the accumulator on the register stack. The accumulator can be restored with a “POP HL”
instruction.
2.2.2 Flag Register
The flag register consists of 3 flags: the carry flag (C), the zero flag (Z) and the G flag (G). When an interrupt
occurs, a “PUSH HL” instruction can be used if necessary to save the flag register on the register stack. The flag
register can be restored with a “POP HL” instruction.
2.2.2.1
Carry Flag (C)
The carry flag (C) is a 1-bit flag that is loaded with a carry during addition or a borrow during subtraction. At
system reset, the carry flag is initialized to “0”.
3
2
1
0
Accumulator
A
G
C
Z
Flag register
Содержание ML63611
Страница 9: ...Chapter 1 Overview...
Страница 33: ...Chapter 2 CPU and Memory Spaces...
Страница 42: ...Chapter 3 CPU Control Functions...
Страница 49: ...Chapter 4 Interrupt INT...
Страница 62: ...Chapter 5 Clock Generator Circuit OSC...
Страница 71: ...Chapter 6 Time Base Counter TBC...
Страница 75: ...Chapter 7 Timers TIMER...
Страница 99: ...Chapter 8 100 Hz Timer Counter 100HzTC...
Страница 103: ...Chapter 9 Watchdog Timer WDT...
Страница 108: ...Chapter 10 Ports INPUT I O PORT...
Страница 140: ...Chapter 11 Melody Driver MELODY...
Страница 152: ...Chapter 12 Serial Port SIO...
Страница 179: ...Chapter 13 LCD Driver LCD...
Страница 200: ...Chapter 14 Battery Low Detect Circuit BLD...
Страница 204: ...Chapter 15 Power Supply Circuit POWER...
Страница 215: ...Chapter 16 A D Converter ADC...
Страница 238: ...Appendixes...
Страница 271: ...ML63611 User s Manual First Edition May 2001 Second Edition June 2001 2001 Oki Electric Industry Co Ltd PEUL63611 02...