Objectives 1. Describe the Intel family of microprocessors. 2. Explain the function of the Execution Unit and BIU. 3. Describe pipelining and how it enables the CPU to work faster. 4. Explain the list of registers of 8086 and this operation. Introduction Webster's New Twentieth Century Dictionary defines microprocessor as "the controlling unit of a microprocessor, laid out on a tiny chip and containing the logical elements for handling data, performing calculations, carrying out stored instructions, etc." Intel has brought out a series of microprocessors. The characteristic of each starting from 4-bit microprocessor to 64 bits microprocessor is listed below. For each processor note the number of transistors used, the clock speed, number of bits as well as the pin package has been indicated. There are many other features which will be discussed in detail as we go through the course. Intel brought out the first 4 bit processor (1971) • 2300 transistors • 400 – 800 kHz • 4-bit word size • 16-pin DIP package 8-bit processor (1974-1976) 8085 Microprocessor • 4.5k – 6.5k transistors • NMOS Technology • 5-10 MHz • 8-bit word size • 40-pin DIP package • No. of instructions 111/113 • 64K memory • Address lines 16 • Data lines 8 • Microcode ROM 16-bit processor (1978-1979) 8086/8088 Microprocessor • 3 µm process • NMOS Technology • 29k transistors • 5-10 MHz • 133 Instructions • 16-bit word size • 40-pin DIP package • 1 M Bytes Physical Memory • Microcode ROM 8-bit layout 16-bit layout
Difference between 8085 and 8086 No Description 8085 8086 1 Address lines 16 20 2 Memory 64K 1MB 3 Data Bus 8 16 4 Co-processor - 8087 5 Operating system CP/M DOS CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created for Intel 8080/85-based microcomputers by Gary Kildall of Digital Research, Inc. Difference between 8086 and 8088 Processor No Description 8088 8086 1 Address lines 20 2 Memory 1MB 1MB 3 Data Bus 8 16 4 Co-processor 8087 8087 5 Operating system DOS OS/2 20 80286 Microprocessor Virtual memory (1982) 1.5 µm process • NMOS Technology • 134k transistors • 10-16 MHz • 16-bit word size • 16M Physical Memory • 68-pin PGA(pin grid array) • Bit-slices clearly visible Difference between 8086 and 80286 No Description 8086 80286 1 Address lines 20 24 2 No. of Pins 40 68 3 Virtual Memory Nil 1G
4 Physical memory 1M 16M 5 Protective mode Nil 16MB 80386 Microprocessor 32-bit processor (1985): CMOS Tech • 1.5-1 µm process • 275k transistors • 16-33 MHz • 32-bit word size • 132-pin PGA • 32 Address lines • 32-bit data-path, • 64 T Bytes Virtual Memory • Synthesized control 80486 Microprocessor • Pipelining (1989) • CMOS Tech. • Floating point unit • 8 KB cache • 168 pins • 1-0.6 µm process • 1.2M transistors • 25-33 MHz • 32-bit word size • Cache, Integer data path, • FPU, microcode, • synthesized control • 168-pin PGA • 64 T Bytes Virtual memory Pentium Processor Superscalar (1993) 2 instructions per cycle Separate 8KB Cache I$ & D$ 0.8-0.35 mm process 3.2M transistors 60-300 MHz 32-bit word size 296-pin PGA 4G Bytes Physical memory. 64T Bytes Virtual memory Caches, data-path, FPU, control Pentium Pro / II / III Dynamic execution (1995-99) • 3 micro-ops / cycle • Out of order execution • 16-32 KB Cache I$ & D$ • Multimedia instructions • PIII adds 256+ KB L2$ Cache
• • • • • • Dynamic execution (1995-99) 3 micro-ops / cycle Out of order execution 16-32 KB Cache I$ & D$ Multimedia instructions PIII adds 256+ KB L2$ Cache Pentium 4 Deep pipeline (2001) Very fast clock 256-1024 KB L2$ Characteristics 180 – 90 nm process 42-125M transistors 1.4-3.4 GHz 32-bit word size 478-pin PGA Units start to become invisible on this scale 8086 Microprocessor The Intel 8086 p is a 16-bit microprocessor intended to be used as a CPU in a microcomputer. The term "16-bits" means that its arithmetic logic unit, internal registers, and most of its instructions are designed to work with 16-bit binary words. The 8086 have a 16-bit data bus, so that it can read data from or write data to memory and ports (16-bits or 8-bits at a time). The 8086 contain approximately 29000 transistors and is fabricated using the HMOS technology. The 8086 can be operated at 3 different clock speeds. The standard 8086 runs at 5Mhz and the other versions of the 8086, the 8086-2 and 8086 -1 permit a clock frequencies of up to 8Mhz and 10Mhz respectively. 8086/8088 - CPU Architecture The 8086/8088 architecture can be broadly divided into two groups: (i) Execution Unit (EU) (ii) Bus Interface Unit (BIU) The execution unit contains the Data and Address registers, the Arithmetic and Logic Unit and the Control Unit. The Bus Interface Unit contains Bus Interface Logic, Segment registers, Memory addressing logic and a Six byte instruction object code queue (4-byte instruction object-code queue in case of 8088 microprocessor). The execution unit and the Bus Interface unit operate asynchronously. The EU waits for the instruction object code to be fetched from the memory by the BIU. The BIU fetches or pre-fetches the object code (16-bits at a time) and loads it into the six bytes queue. Whenever the EU is ready to execute a new instruction, it fetches the instruction object code from the front of the instruction queue and executes the instruction in specified number of clock periods. If memory or Input/output devices must be accessed in the course of executing an instruction, then the EU informs the BIU of its needs. The BIU completes its operation code (opcode) fetch cycle, if in progress, and executes an appropriate external access machine cycle in response to the EU demand.