BS85B12-3 HOLTEK [Holtek Semiconductor Inc], BS85B12-3 Datasheet - Page 25

• Manufacturer Part Number: BS85B12-3
• Description: Touch Key Flash Type 8-Bit MCU with LCD/LED Driver
• Manufacturer: HOLTEK [Holtek Semiconductor Inc]

BS85B12-3/BS85C20-3
Touch Key Flash MCU with LCD/LED Driver
Flash Program Memory
Rev. 1.00
Arithmetic and Logic Unit - ALU
Structure
The arithmetic-logic unit or ALU is a critical area of the microcontroller that carries out arithmetic and
logic operations of the instruction set. Connected to the main microcontroller data bus, the ALU
receives related instruction codes and performs the required arithmetic or logical operations after
which the result will be placed in the specified register. As these ALU calculation or operations may
result in carry, borrow or other status changes, the status register will be correspondingly updated to
reflect these changes. The ALU supports the following functions:
The Program Memory is the location where the user code or program is stored. For this device series
the Program Memory is Flash type, which means it can be programmed and re-programmed a large
number of times, allowing the user the convenience of code modification on the same device. By using
the appropriate programming tools, these Flash devices offer users the flexibility to conveniently
debug and develop their applications while also offering a means of field programming and updating.
The Program Memory has a capacity of 2K 15 bits or 4K 15 bits. The Program Memory is addressed
by the Program Counter and also contains data, table information and interrupt entries. Table data,
which can be setup in any location within the Program Memory, is addressed by a separate table
pointer register.
Arithmetic operations: ADD, ADDM, ADC, ADCM, SUB, SUBM, SBC, SBCM, DAA
Logic operations: AND, OR, XOR, ANDM, ORM, XORM, CPL, CPLA
Rotation RRA, RR, RRCA, RRC, RLA, RL, RLCA, RLC
Increment and Decrement INCA, INC, DECA, DEC
Branch decision, JMP, SZ, SZA, SNZ, SIZ, SDZ, SIZA, SDZA, CALL, RET, RETI
BS85B12-3
BS85C20-3
Device
Capacity
2Kx15
4Kx15
19
Flash Program Memory Structure
February 1, 2011