1. Basic Concept of Labels In assembly language, a label is a symbolic name used to mark memory addresses. In 8086 assembly, there are two types of labels: Regular Labels: Represents only the address of a memory unit Labels with Unit Length: Represents not only the address but also implicitly includes the length information of … Read more
ret and retf Instructions <span>call</span> and <span>ret</span> are transfer instructions that control the program flow by modifying the IP (Instruction Pointer) or simultaneously modifying both the CS (Code Segment Register) and IP. These instructions are typically used together to implement the design of subroutines (functions). ret Instruction <span>ret</span> (return) instruction pops data from the stack … Read more
1. Problem Analysis We need to write a subroutine that displays a given byte of data in hexadecimal format at the center of the screen. One byte should be represented by two hexadecimal characters, corresponding to the high 4 bits and low 4 bits of the value. Key Points: Separate the high 4 bits and … Read more
1. Overview of CPU I/O Capabilities The CPU not only has computational capabilities but also needs to exchange data with external devices, a capability known as I/O (Input/Output) capability. Typical I/O operations in a computer system include: Keyboard input Display output Disk read/write Network communication, etc. 2. Two Core Issues in Peripheral Interaction 1. Peripheral … Read more
1. Abstract A single-chip microcomputer (Single-Chip Microcomputer) is a microcontroller that integrates CPU, RAM, ROM, timing, counting, and various interfaces into one. It is small in size, low in cost, powerful in function, and widely used in smart products and industrial automation. The 51 microcontroller is one of the most typical and representative microcontrollers. This … Read more
I am Lao Wen, an embedded engineer who loves learning.Follow me to become even better together!Program Structure Optimization 1. Program Writing Structure Although the writing format does not affect the quality of the generated code, certain writing rules should still be followed during actual programming. A clearly written program is beneficial for future maintenance. When … Read more
1. Write the C language program ch03_06_01.c /* * The goal of this program is to count the occurrences of a specific character in a given string and print the result. * The length of a char is 1 byte, while the length of a char* is 8 bytes (refer to "Computer Systems: A Programmer's … Read more
1.Introduction to x86 x86 is a CISC architecture introduced by Intel in 1978, named after early processor models (such as 8086). Its core features include complex instruction set design and backward compatibility, supporting a smooth transition from 16-bit to 64-bit. Throughout its historical evolution, the 80386 marked the beginning of the 32-bit era, while AMD64 … Read more
Place MASM in the D drive. Start DOSBox and enter mount c d:\masm and press Enter. This command mounts the D drive MASM as the C drive. Because when you first start, it is on the Z drive. Next, enter c: and press Enter; it has successfully started and is now usable. General-purpose registers: AX, … Read more
The Basic Meaning of ‘Arm’ As a noun, the most common meaning of ‘arm’ is “arm; limb”; it can also refer to “weapons; armed forces”; as a verb, it means “to arm; to equip”. Examples of Noun Usage Arm; Limb She held the baby in her arms. (She held the baby in her arms.) Weapons; … Read more