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  2. MCS-51 - Wikipedia

    en.wikipedia.org/wiki/MCS-51

    [3] [48] It can perform as an 8-bit 8051, has 24-bit linear addressing, an 8-bit ALU, 8-bit instructions, 16-bit instructions, a limited set of 32-bit instructions, 16 8-bit registers, 16 16-bit registers (8 16-bit registers which do not share space with any 8-bit registers, and 8 16-bit registers which contain 2 8-bit registers per 16-bit ...

  3. Accumulator (computing) - Wikipedia

    en.wikipedia.org/wiki/Accumulator_(computing)

    The 8051 microcontroller has two, a primary accumulator and a secondary accumulator, where the second is used by instructions only when multiplying (MUL AB) or dividing (DIV AB); the former splits the 16-bit result between the two 8-bit accumulators, whereas the latter stores the quotient on the primary accumulator A and the remainder in the ...

  4. Half-carry flag - Wikipedia

    en.wikipedia.org/wiki/Half-carry_flag

    It is primarily used to support binary-coded decimal (BCD) arithmetic. The Auxiliary Carry flag is set (to 1) if during an "add" operation there is a carry from the low nibble (lowest four bits) to the high nibble (upper four bits), or a borrow from the high nibble to the low nibble, in the low-order 8-bit portion, during a subtraction ...

  5. Carry flag - Wikipedia

    en.wikipedia.org/wiki/Carry_flag

    Another example may be an 8-bit register with the bit pattern 01010101 and the carry flag set; if we execute a rotate left through carry instruction, the result would be 10101011 with the carry flag cleared because the most significant bit (bit 7) was rotated into the carry while the carry was rotated into the least significant bit (bit 0).

  6. 8-bit computing - Wikipedia

    en.wikipedia.org/wiki/8-bit_computing

    An 8-bit register can store 2 8 different values. The range of integer values that can be stored in 8 bits depends on the integer representation used. With the two most common representations, the range is 0 through 255 (2 8 − 1) for representation as an binary number, and −128 (−1 × 2 7) through 127 (2 7 − 1) for representation as two's complement.

  7. FLAGS register - Wikipedia

    en.wikipedia.org/wiki/FLAGS_register

    The FLAGS register is the status register that contains the current state of an x86 CPU.The size and meanings of the flag bits are architecture dependent. It usually reflects the result of arithmetic operations as well as information about restrictions placed on the CPU operation at the current time.

  8. Parity flag - Wikipedia

    en.wikipedia.org/wiki/Parity_flag

    an instruction or interrupt that causes a hardware task switch; In conditional jumps, parity flag is used, where e.g. the JP instruction jumps to the given target when the parity flag is set and the JNP instruction jumps if it is not set. The flag may be also read directly with instructions such as PUSHF, which pushes the flags register on the ...

  9. Microsequencer - Wikipedia

    en.wikipedia.org/wiki/Microsequencer

    All the arithmetic/logical instructions allow the jump (J) modifier, which redirects execution to the microinstruction addressed by the Link register. All the arithmetic/logical instructions allow both the decrement counter (D) and jump (J) modifiers. In this case, the 8-bit loop counter register is decremented.