CPU Function
The CPU (central processing unit) is the primary component of a computer that performs instructions and processes data. It carries out arithmetic, logic, and input/output operations as directed by the computer's software. The CPU's function is to execute program instructions and coordinate the activities of the computer's other hardware components.
5 Key excerpts on "CPU Function"
eBook - ePub- David Johnson(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
...4 The Central Processing Unit Although referred to as the brain of the system, the Central Processing Unit in a normal installation is the unsung hero, buried in a control cabinet, all but forgotten. 4.1 BASIC FUNCTIONALITY In a programmable controller system, the central processing unit (CPU) provides both the heart and the brain required for successful and timely control execution. It rapidly and efficiently scans all of the system inputs, examines and solves the application logic, and updates all of the system outputs. In addition, it also gives itself a checkup each scan to ensure that its structure is still intact. In this chapter we will examine the central processing unit as it relates to the entire system. Included will be the various functional blocks in the CPU, typical scan techniques, I/O interface and memory uses, power supplies, and system diagnostics. 4.2 TYPICAL FUNCTION BLOCK INTERACTIONS In practice, the central processing unit can vary in its architecture, but consists of the basic building block structure illustrated in Figure 4.1. The processor section consists of one or more microprocessors and their associated circuitry. While it is true that some of the older generation programmable controllers were designed without the luxury of using microprocessors, most modern systems use either a single microprocessor such as the 8086 or Z-80, or multiple microprocessors such as the AMD2903, used in a bit slice architecture. This multi-tasking approach is used in the multiple microprocessor system to break the control system tasks into many small components which can be executed in parallel. The result of this approach is to achieve execution speeds that are orders of magnitude faster than their single-tasking counterparts...
eBook - ePubElectronics Explained
The New Systems Approach to Learning Electronics
- Louis E. Frenzel(Author)
- 2010(Publication Date)
- Newnes(Publisher)
...One special type of microcomputer is the programmable logic controller (PLC) used for industrial control (Chapter 12). The larger microcomputers, such as personal computers, are made with a microprocessor. A microprocessor is a large-scale integrated circuit that contains most of the digital logic circuitry usually associated with a digital computer. This logic circuitry is referred to as the central processing unit (CPU). A microprocessor is a single-chip CPU. Another common micro is called a core. A core is a microprocessor or microcomputer integrated with some other circuits. The core is made on the same silicon chip as a cell phone or a security device. Today multicore micros are common. Two or more cores are used to get more processing power. Embedded microcontrollers are complete micros on a single chip, including the CPU, memory, and input/output circuits. But in all cases, a microcomputer is an assembly of digital logic circuits, such as gates and flip-flops, that is used to process data. It is sometimes referred to as a data processor, or simply processor. Data, of course, refers to the binary numbers and words the processor works with. Processing refers to the way the data is manipulated or handled. Types of processing include arithmetic, logic, sorting, translating, editing, counting, and searching. Any action taken on the data is called processing. Processing normally implies that the data is changed in some way or is used to create new data. Data that is not processed as suggested above is dealt with in other ways. Four common ways are storing, retrieving, input, or output...
- Mohamed Rafiquzzaman(Author)
- 2021(Publication Date)
- CRC Press(Publisher)
...1 INTRODUCTION TO MICROPROCESSORS AND MICROCOMPUTER-BASED APPLICATIONS This chapter provides a brief summary of the features of microprocessors and microcomputer-based applications. The basic elements of a computer are the Central Processing Unit (CPU), the Memory, and Input/Output (I/O) units. The CPU translates instructions, performs arithmetic or logic operations, and temporarily stores instructions and data in its internal high-speed registers. The memory stores programs and data. The I/O unit interfaces the computer with external devices such as keyboard and display. With the advent of semiconductor technology, it is possible to integrate the CPU in a single chip. The result is the microprocessor. Metal Oxide Semiconductor (MOS) technology is typically used to fabricate the standard off-the-shelf microprocessors such as those manufactured by Intel and Motorola. Appropriate memory and I/O chips are interfaced to the microprocessor to design a microcomputer. Single-chip microcomputers are also available in which the microprocessor, memory, and I/O are all fabricated in the same chip. These single-chip microcomputers offer limited capabilities. However, they are ideal for certain applications such as peripheral controllers. Single chip microcomputers are also referred to as “microcontrollers”. The microcontrollers are typically used for dedicated applications such as automotive systems, home appliances and home entertainment systems. Typical microcontrollers, therefore, include on-chip timers, A/D (Analog to Digital) and D/A (Digital to Analog) converters. Two popular microcontrollers are Intel 8751 (8-bit)/8096 (16-bit) and Motorola HC11 (8-bit)/HC16 (16-bit). The 16-bit microcontrollers include more on-chip ROM, RAM, and I/O compared to the 8-bit microcontrollers. The efficient development of microprocessor-based systems necessitates the use of a microcomputer development system...
- Ed Lipiansky(Author)
- 2012(Publication Date)
- Wiley-IEEE Press(Publisher)
...10 A SIMPLE CPU DESIGN The design of a simplified central processing unit (CPU) is covered in this chapter. This design exemplifies a somewhat more involved and practical design than the examples studied in the previous chapter. This entire chapter basically is a huge example that shows the most important considerations when designing a simple CPU. We start defining the CPU instruction set and the machine instruction word. What the instructions do. The registers, memory, and combinational logic blocks are the components that the CPU requires to be able to execute the defined instruction set. We will also cover the design of the sequencer or control section of the machine with the details of its state diagram and circuit implementation. Finally, a system section covers some of the most important aspects, and sometimes overlooked issues of embedded system design: clocks, resets, power decoupling, and timing. The goal of this chapter is not only to cover a simple CPU but at the same time a complex enough design example that is more comprehensive than previously covered design examples. The basic approach taken is mostly bottom up. 10.1 OUR SIMPLE CPU INSTRUCTION SET This section introduces the reader to our small CPU instruction set. The instruction set is carefully picked such that various types of the most popular machine language instructions are represented. We will not categorize this design neither as a CISC or RISC example. CISC stands for Complex Instruction Set Computer and RISC stands for Reduced Instruction Set Computer. From a computer architecture point of view our design is closer to a von Neumann machine. This is an architecture that consists of a stored-program digital machine that has a central processing unit and a single separate memory unit that holds program instructions as well as data...
eBook - ePub- J S Anderson(Author)
- 2012(Publication Date)
- Routledge(Publisher)
...The microprocessor or CPU itself is obviously the most important part. It controls all the automatic actions which take place, accesses the memory units, fetches and executes instructions, performs arithmetic and logic calculations, monitors external events and keeps track of where it has got to. The memory of the system holds the program and various types of data. The I/O or input/output devices of the system allow the user to ‘talk’ to the computer in a familiar manner, for example, uses a typewriter-style keyboard, or in many modern systems a mouse in association with pull-down menus. A typical output system is of course the VDU – video display unit. The buses provide interconnections for the various parts of the system. Questions 1 List the great advantages of using integrated circuits in micro-electronics and microcomputer systems. 2 State: (a) how many bits there are in a byte; (b) the name for 1024 bytes. 3 Assuming a memory device made up from basic flip-flop elements, how many transistors would be required to construct an 8K memory? 4 (a) Describe the differences between RAM and ROM. (b) What is meant by ‘volatile’ and ‘non-volatile’? 5 Draw a simple diagram of a Z80 CPU (or a 6502 CPU) showing; registers, control, ALU, IR, flags and PC, 6 What is the function of the instruction register? 7 (a) What is the function of the ALU? (b) Where are the results of ALU operations sent to? (c) What other register may the ALU affect? 8 What is the ‘stack’ used for, and what is special about it? 9 Why might a 16-bit processor have an 8-bit data bus? 10 (a) How is a microprocessor system word length determined? (b) Draw and label 8-bit and 16-bit words (c) Draw and label a typical microprocessor system. Assignment 3.1 (a) Looking at the memory chip pin-outs given in Appendix II, and using manufacturers’ literature where necessary, select two RAM and two EPROM devices...
