Microprocessor and Microcontrollers ( CSE-3501) Lecture-2

1. Microprocessor and Microcontrollers (CSE-3501)Lecture-2 Instructor: SazidZaman Khan Lecturer, Department of Computer Science and Engineering, IIUC

2. Microprocessor based personal computer system Connected by Buses Memory System (RAMs CACHE. ROM) Microprocessor Input/output System (Printer, hard disk, mouse, monitor, DVD, etc) Figure-1: Microprocessor based Computer System [Fig-1-6 [Barry b. Bray-8th edition, p.18]]

3. The memory and I/O System Figure-2: Memory map of a personal computer[Fig-1-7 [Barry b. Bray-8th edition, p.18]]

4. The memory and I/O System • The memory system is divided into three main parts: TPA, System Area and Extended memory system. • TPA (Transient Program Area) :Holds the DOS (Disk Operating System) and other programs that control the computer system. TPA is not really an applicable concept in Windows. Figure-3: Memory map of TPA [B. Brey Fig-1-8 [p.20]]

5. The memory and I/O System • BIOS (basic input/output system) is the program a personal computer's microprocessor uses to get the computer system started after you turn it on. It also manages data flow between the computer's opearting system and attached devices such as the hard disk, keyboard, mouse, etc. • When BIOS boots up (starts up) your computer, it first determines whether all of the attachments are in place and operational and then it loads the operating system (or key parts of it) into your computer's random access memory (RAM) from your hard disk or disk drive.

6. The memory and I/O System • IO.SYS is a program that loads into the TPA from disk when an MSDOS system is started. It contains programs that allow DOS (Disk Operating System) to use the I/O devices. • Drivers are programs that control installable I/O devices such as a mouse, disk cache, hand scanner, CD- ROM memory, DVD. DOS drivers are normally files that have an extension of SYS or EXE. In Windows, a registry is used to contain information about the system and drivers used by the system.

7. The memory and I/O System • COMMAND.COM program controls the operation of the computer from the keyboard when operated in the DOS mode. • For example, if DIR is typed, the COMMAND.COM program displays a directory of the disk files in the present directory.

8. System Area • The DOS system area although smaller than TPA contains programs on either a ROM or flash memory and areas of RAM for data storage. This area starts at A0000H-FFFFFH. Can you tell the size of the area from this address range? (I showed in the first class). • In windows, it is from 00000000H- FFFFFFFFH (What’s the size from this range?).

9. I/O Space • The I/O space in a computer extends from I/O port 0000H-FFFFH (An I/O port address is similar to a memory address, except that it addresses I/O devices).

10. System buses • In computer architecture, a bus is a transmission path that transfers data (actual data, address data or control data) between components inside a computer, or between computers. • Address bus carries address, data bus carries data and control bus carries control information.

11. Functions of Buses • 1. Data sharing - All types of buses found on a computer must be able to transfer data between the computer peripherals connected to it. • 2. Addressing - A bus has address lines, which match those of the processor. This allows data to be sent to or from specific memory locations. • 3. Power - A bus supplies power to various peripherals that are connected to it. • 4. Timing - The bus provides a system clock signal to synchronize the peripherals attached to it with the rest of the system.

12. Expansion buses • Devices such as keyboards and mice are so common that their controller circuitry and connectors are built right into the motherboard.  Even audio, video and LAN capabilities - at one time considered "specialized" devices - are now built into most motherboards.  Such motherboards are designed for their simplicity, and will usually decrease the cost of the overall PC.  However, it makes the system more expensive to repair, since a faulty component will usually require the entire motherboard to be replaced. However, integrated motherboards are not always suited for specialized applications.  For example, the data transfer rate for integrated video (133 MB/s) may not be enough for games or high-end graphics applications.  In addition, you may want to connect a specialized device that does not have a suitable port or connector on the motherboard.  For these devices, the controller circuitry and connectors are built into special circuit boards called expansion cards (or controller cards, or adapter cards), which are physically inserted into special “expansion slots” on the motherboard.

13. Expansion buses • The narrow channel in each expansion slot contains tiny copper contacts, which are connected to expansion buses.  When an expansion card is inserted into the expansion slot, a connection is made between the contacts in the slot and the copper “fingers” on the expansion card.  This allows the expansion card to use the associated expansion bus to communicate with an appropriate support chip, which ultimately allows the  device to communicate with the CPU.

14. Expansion buses

15. Some Expansion bus types • Expansion Bus Types: These are some of the common expansion bus types that have ever been used in computers: • PCI - Peripheral Component Interconnect • PCMCIA - Personal Computer Memory Card Industry Association (Also called PC bus) • AGP - Accelerated Graphics Port • SCSI - Small Computer Systems Interface

16. Expansion bus types • Peripheral Component Interconnect (PCI): It is one of the latest developments in bus architecture and is the current standard for expansion cards. It was developed by Intel and launched as the expansion bus for the Pentium processor in 1993. It connects the CPU, memory and peripherals to wider, faster data pathway. • PCI supports both 32-bit and 64-bit data width; therefore it is compatible with 486s and Pentiums.

17. Expansion bus types • AGP: The need for high quality and very fast performance of video on computers led to the development of the Accelerated Graphics Port (AGP). The AGP Port is connected to the CPU and operates at the speed of the processor bus. This means that video information can be sent more quickly to the card for processing. The AGP uses the main PC memory to hold 3D images. In effect, this gives the AGP video card an unlimited amount of video memory. 

18. Expansion bus types • PC card: The Personal Computer Memory Card Industry Association was founded to provide a standard bus for laptop computers. So it is basically used in the small computers. • SCSI: Short for Small Computer System Interface, a parallel interface standard used by Apple Macintosh computers, PC's and Unix systems for attaching peripheral devices to a computer.

19. Expansion bus types • USB : This is an external bus standard that supports data transfer rates of 12 Mbps. A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. The USB also supports hot plugging/insertion (ability to connect a device without turning the PC of) and plug and play (You connect a device and start using it without configuration).