Assembly Language Learning Notes (8)--basic problems in data processing

1, only "BX, Si, Di, BP" Four registers can be used in the [...] To address the memory cells in the

2. These four registers can appear either individually or in [By+zi] form, where y=x or p,z = s or D, other formats are wrong.

3, when using BP. Assume that the segment address is not explicitly given. The segment address defaults to the SS segment register.

4, assembly language with three concepts to express the location of data:

Immediate Number (Idata):

"Data" directly included in the machine instruction (in the "instruction buffer" of the CPU before running), given directly in the assembly instruction

Register

The "data" in the instruction to be processed is in "registers". The corresponding register name is given in the assembly instruction

Segment address and offset address

The "data" in the instruction to be processed is in "Memory", the segment address is in a segment register, the offset address is given by [X]

5, when the data in memory, there are multiple addressing methods. It is generally in [...] The offset address is given in the The offset address can be a single register in the four registers described in 1th. It can also be a combination of one or two registers in these four registers with the number of immediate numbers.

6. Indicate the size of the data to be processed:

(1). indicated by the register name, such as Al represents the data as a single byte. Ax is two bytes
(2). Specify the memory unit length with the operator x ptr. X = Word or byte
(3). Push instruction only for word manipulation

7, Div in the Assembly for Division instruction

The divisor has 8 bits and 16 bits, which are stored in registers or in memory. Assuming that the divisor is 8 bits, the divisor is in Ax, and Al stores the quotient of division operations, AH stores the remainder; assuming a divisor of 16 bits. The lower 16 bits of the divisor are present in ax. High 16 bits exist in DX. In the presence of Microsoft Dynamics AX, the remainder exists in DX.

8, DB defines "byte-type" data. DW defines "font" data, DD defines "double-font" data

9, the DUP operator and DB, DD, DW with the use of data repeatedly

Assembly Language Learning Notes (8)--basic problems in data processing