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 incorrect.

3, when using BP, if not explicitly given the segment address, then the segment address by default in the SS segment register.

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

Immediate Number (Idata):

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

Register

The "data" in the instruction to be processed is in "register" and 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, is generally in the [...] , the offset address can be a single register in the four registers described in 1th, or a combination of one or two registers and an immediate number in these four registers.

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

(1). indicated by register name, such as Al represents data as one 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 operation

7, Div in the Assembly for Division instruction

The divisor has 8 bits and 16 bits, which are stored in registers or in memory, if the divisor is 8 bits, the divisor is in Ax, the AL stores the division operation Quotient, AH stores the remainder; if the divisor is 16 bits, then the divisor of the low 16 bits exists in AX, the high 16 bits exist in the DX, the remainder exists in the DX.

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

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

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

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