Chapter 1 Microprocessor-based systems EE314 Microprocessor Systems Based on "An Introduction to the Intel Family of Microprocessors" by James L. Antonakos

1.1 Introduction Examples of devices using microprocessors (  P) Pocket calculators Digital watches Automatic tellers Smart telephones Compact disk players Home security devices Realistic video games Toys VCRs Personal computers

1.2 Evolution of Microprocessors Computers “generations” First generationENIAC (vacuum tubes) Second generation(transistors) Third generation(IC - SSI, MSI) Fourth generation(LSI) Fifth generationcan think? Microprocessors MSIIntel® 4004™, 8008™ LSIIntel® 8080™, Zilog® Z80™, Motorola® 6800™ 8 bit data bus, 16 bit address bus (64kbyte=65536 byte of addressable memory), no multiply and divide instructions VLSI32…64 bit data bus, 2-300MHz clock, RISC concept

1.3 System block diagram System bus (data, address & control signals) Memory Interrupt circuitry Serial I/O Parallel I/O TimingCPU  P + associated logic circuitry: Bus controller Bus drivers Coprocessor ROM (Read Only Memory) (start-up program) RAM (Random Access Memory) DRAM (Dynamic RAM) - high capacity, refresh needed SRAM (Static RAM) - low power, fast, easy to interface Crystal oscillator Timing circuitry (counters dividing to lower frequencies) At external unexpected events,  P has to interrupt the main program execution, service the interrupt request (obviously a short subroutine) and retake the main program from the point where it was interrupt. Simple (only two wires + ground) but slow. Printer (low resolution) Modem Operator’s console Mainframe Personal computer Many wires, fast. Printer (high resolution) External memory Floppy Disk Hard Disk Compact Disk Other high speed devices

1.6 The Personal Computer Processor (8086 trough Pentium System bus (data, address & control signals) System ROM Interrupt logic (8259) Keyboard logic (8253) DMA Controller (8237) Timer logic (8253) Coprocessor (8087 trough KB DRAM Expansion logic Keyboard Speaker Extension slots Video card Disk controller Serial port...

;NUMOFF.ASM: Turn NUM-LOCK indicator off. ;.MODEL SMALL.STACK.CODE.STARTUP MOV AX,40H;set AX to 0040H MOV DS,AX;load data segment with 0040H MOV SI,17H;load SI with 0017H AND BYTE PTR [SI],0DFH;clear NUM-LOCK bit.EXIT END All characters following a “;” till the line end are “comments”, ignored by the assembler Assembler reserved words Assembly language instructions 1.7 Developing software for the personal computer.ASM file

;NUMOFF.ASM: Turn NUM-LOCK indicator off. ;.MODEL SMALL.STACK.CODE.STARTUP MOV AX,40H;set AX to 0040H MOV DS,AX;load data segment with 0040H MOV SI,17H;load SI with 0017H AND BYTE PTR [SI],0DFH;clear NUM-LOCK bit.EXIT END Register pair (16 bit) (destination of “MOV”) Hexadecimal value to be loaded (source for “MOV”) Data Segment register pair Prepare the Data Segment Source Index The complete address of the byte containing NumLock bit is specified. First operand and destination for logical “AND” Memory address specified by DS and SI together. Second operand for logical “AND” (immediate hexadecimal value) AND ing with DFH= B, only b5 (bit 5) of specified memory location is affected (reset to 0)

;NUMOFF.ASM: Turn NUM-LOCK indicator off. ;.MODEL SMALL.STACK 0000.CODE.STARTUP 0017 B MOV AX,40H ;set AX to 0040H 001A 8E D8 MOV DS,AX ;load data segment with 0040H 001C BE 0017 MOV SI,17H ;load SI with 0017H 001F DF AND BYTE PTR [SI],0DFH ;clear NUM-LOCK bit.EXIT END Memory location addresses Machine language codes generated by the assembler 1.7 Developing software for the personal computer.LST file