st72324bk STMicroelectronics, st72324bk Datasheet - Page 21

• Manufacturer Part Number: st72324bk
• Description: 3 V/5 V Range 8-bit Mcu With 4/8 Kbyte Rom, 10-bit Adc, Four Timers And Spi
• Manufacturer: STMicroelectronics

ST72323 ST72323L
4
4.1
4.2
4.3
4.3.1
4.3.2
4.3.3
Central processing unit
Introduction
This CPU has a full 8-bit architecture and contains six internal registers allowing efficient 8-
bit data manipulation.
Main features
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CPU registers
The 6 CPU registers shown in
accessed by specific instructions.
Accumulator (A)
The Accumulator is an 8-bit general purpose register used to hold operands and the results
of the arithmetic and logic calculations and to manipulate data.
Index registers (X and Y)
These 8-bit registers are used to create effective addresses or as temporary storage areas
for data manipulation. (The Cross-Assembler generates a precede instruction (PRE) to
indicate that the following instruction refers to the Y register.)
The Y register is not affected by the interrupt automatic procedures.
Program counter (PC)
The program counter is a 16-bit register containing the address of the next instruction to be
executed by the CPU. It is made of two 8-bit registers PCL (Program Counter Low which is
the LSB) and PCH (Program Counter High which is the MSB).
Enable executing 63 basic instructions
Fast 8-bit by 8-bit multiply
17 main addressing modes (with indirect addressing mode)
Two 8-bit index registers
16-bit stack pointer
Low power Halt and Wait modes
Priority maskable hardware interrupts
Non-maskable software/hardware interrupts
Figure 8
are not present in the memory mapping and are
Central processing unit
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