ELEC1700 Computer Engineering 1 Week 12 Monday lecture Microprocessor systems Semester 1, 2013

1. ELEC1700Computer Engineering 1Week 12 Monday lectureMicroprocessor systems Semester 1, 2013

2. Introduction to microprocessor systems Intel 8051 Microprocessor systems

3. Basic computer organisation • CPU = Central Processing Unit • fetches instructions from memory, decodes and executes instructions • Memory & storage • Non-volatile ROM stores BIOS = lowest level of operating system • RAM stores data used by programs • Buses • Address bus carries memory or I/O locations • Data bus carries memory or I/O contents • Control bus transfers control signals to/from CPU

4. ELEC2700 — microprocessor system design & interfacing ELEC3720 — design & implement your own microprocessor

5. Elements of a microprocessor • ALU = arithmetic & logic unit • +, –, ×, /, sin, cos, exp, … • AND, OR, NOT • Register array • Registers store groups of bits in groups of flip-flops • Store temporary results during program execution • Control unit + instruction decoder • State machine • Provides timing and control signals for ALU, instruction decoder, registers and memory

6. Multi-core processors • Multi-core processors • 2 or more microprocessors (“cores”) on one chip • Cores operate in parallel • Dual-core and quad-core processors are now common

7. Pipelining • Instructions divided into pipeline stages • Microprocessor executes multiple stages concurrently • Analogy: making pizzas • 3 stages, each 1-minute long • once pipeline is full: 3 people can make pizzas at rate of 1 per minute

8. Multitasking • Multitasking operating systems (e.g. Windows) switch quickly between many tasks • Programs appear to run simultaneously • Multi-core processors allow fewer tasks per core, with less switching time → faster

9. High-level language /* Hello World program */ #include<stdio.h> main() { printf ("Hello, world\n"); } Assembly language MOV R7,#0AH MOV P0,#00H LOOP: CPL P0.7 DJNZ R7,LOOP Machine language 00110001 00000000 10010000 Computer programming

10. assembler High-level language (HLL) Assembly language Machine language compiler “front-end” “back-end” Compilers and assemblers • Role of the assembler is possible to perform manually • compilation of HLL source into efficient assembly language is difficult—the design of optimising compilers is a course in itself

11. Introduction to microprocessor systems Intel 8051 Microprocessor systems

12. Fetch, decode, execute • Microprocessor program execution: • Fetch instruction from memory • Decode instruction • If other “operand” information is required by the instruction, fetch it from memory • Execute the instruction • Perform the operation, and return results to registers and memory

13. Instructions and data Opcode = “operation code” Unique 1-byte code identifying each instruction to the microprocessor

14. Single- and multi-byte instructions • Single-byte instructions • opcode only • Multi-byte instructions • opcode followed by one or two operand bytes

15. Programmer’s model of the 8051 • General purpose registers R0,…,R7 • Accumulator A • Program counter PC

16. General purpose registers • 8-bit general-purpose registers • R0,R1,…,R7 • Registers are used for holding: • temporary results of computations • addresses of data in memory Examples MOV R1,#0F3H Load register R1 with value F3 hexadecimal MOV P3,@R1 Send the contents of RAM, whose address is in register 1, to port 3

17. Accumulator (A) Processor status Word (PSW) Arithmetic and logic unit (ALU) Accumulator (A) 8-bit accumulator (A) • holds one operand before the arithmetic/logic operation and the result after the operation Example ANL A,R2 Logically AND register R2 (bit by bit) with accumulator, and store result in accumulator

18. Program counter (PC) PC • 16-bit program counter (PC) keeps track of addresses of instructions and data read from memory • PC is normally incremented by CPU control unit as successive instructions are fetched from memory 8000 : 7FFE16 : 7FFF16 1-byte instruction byte 1 800016 byte 1 800116 2-byte instruction byte 2 800216 : 800316

19. Some 8051 instructions • uses mnemonic representations for opcodes, data and addresses • abbreviations intended to assist the memory of programmers

20. Application: microwave oven control Jump to correct address to start program Decide if value in accumulator is zero If A ≠ 0, display accumulator value at port 1 Wait 1 second Decrease accumulator value by 1 Repeat from step 3 until value in accumulator is zero

21. 8051 assembly language example

22. 8051 assembly language example Address contents Assembly language 000002 LJMP 0100H 000101 000200 010060 JZ 010AH 010108 0102F5 MOV P1, A 010390 010412 LCALL 1__SEC__DELAY 010528 010655 010714 DEC A 010870 JNZ 0102H 0109F8

23. 8051-based system • Microcontroller = CPU + RAM + ROM + IO ports on one chip • “Embedded applications”— dishwashers, cameras, electric toothbrushes, vending machines, keyboards, …

24. 8051 microcontroller • Just a few dollars each • $3.88 in single unit quantities http://bit.ly/KtFMoo • Can also buy as an IP core (intellectual property core) for Altera FPGAs and CPLDs http://bit.ly/M4yslc 8051 is the microprocessor used in ELEC2700