Скачать презентацию Chapter 7 Input Output Continued Interrupt Physical Model Скачать презентацию Chapter 7 Input Output Continued Interrupt Physical Model

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Chapter 7 Input/Output Continued Chapter 7 Input/Output Continued

Interrupt Physical Model • CPU • Memory • Device Interrupt Physical Model • CPU • Memory • Device

Interrupt Physical Model • CPU — General Purpose Registers – PC Storage – R Interrupt Physical Model • CPU — General Purpose Registers – PC Storage – R 7 – Stack Pointer R 6 — Program Status Word (PSW) – Includes – – – State Program Priority Condition Codes (CC) — User stack Pointer Storage – USP. saved — Supervisor Stack Pointer Storage – SSP. saved — Hardware to communicate over the BUS • Memory — — User program Interrupt Service Routine Operating System Interrupt Vector Table – • Includes an entry that points to the Interrupt Service Routine (Interrupt vector #) Device — Status/Control Register(s) – Includes: – – Interrupt Enable bit Interrupt bit (sometimes called ready or done) — Priority Level for Interrupt Service Routine (In hardware or firmware) — Interrupt vector number (In hardware or firmware) — Hardware to communicate with CPU over the BUS

Interrupt Sequence 1) What does the programmer do? 2) What does the computer do? Interrupt Sequence 1) What does the programmer do? 2) What does the computer do?

Interrupt Sequence 1) Programmer Action: Enable Interrupts by setting “ intr enable” bit in Interrupt Sequence 1) Programmer Action: Enable Interrupts by setting “ intr enable” bit in Device Status Reg 2) Enabling Mechanism for device: When device wants service, and its enable bit is set (The I/O device has the right to request service), and its priority is higher than the priority of the presently running program, and execution of an instruction is complete, then The processor initiates the interrupt 4) Process to service the interrupt: The Processor saves the “state” of the program (has to be able to return) The Processor goes into Privileged Mode (PSR bit 15 cleared) Priority level is set (established by the interrupting device) The (USP), (R 6) USP. saved register (User. Stack. Pointer. saved) The (SSP. saved) R 6 (Supervisor. Stack. Pointer) The (PC) and the (PSR) are PUSHED onto the Supervisor Stack The contents of the other registers are not saved. Why? The CC’s are cleared 5) The Processor Loads the PC from the Interrupt vector (vectors in 0100: 01 FF) 6) Interrupt Service Routine is executed Ends with an RTI 7) The stored user PSR (POP into PSR), PC (POP into PC), (R 6) SSP. saved, (USP. saved R 6), and the next instruction fetched

DMA Function • DMA controller(s) takes over from CPU for I/O • Additional Module(s) DMA Function • DMA controller(s) takes over from CPU for I/O • Additional Module(s) attached to bus to control DMA operation

Typical DMA Module Diagram Typical DMA Module Diagram

DMA Operation • CPU tells DMA controller: —Read/Write —Device address —Starting address of memory DMA Operation • CPU tells DMA controller: —Read/Write —Device address —Starting address of memory block for data —Amount of data to be transferred • CPU carries on with other work • DMA controller deals with transfer • DMA controller sends interrupt when finished

DMA Transfer Cycle Stealing • DMA controller takes over bus for a cycle • DMA Transfer Cycle Stealing • DMA controller takes over bus for a cycle • Transfer of one word of data • Not an interrupt —CPU does not switch context • CPU suspended between bus cycles —i. e. before an operand or data fetch or a data write • Slows down CPU but not as much as CPU doing transfer

DMA and Interrupt Breakpoints During an Instruction Cycle What could be wrong with this? DMA and Interrupt Breakpoints During an Instruction Cycle What could be wrong with this?

Aside • What effect does caching memory have on DMA? • What effect does Aside • What effect does caching memory have on DMA? • What effect does use of DRAMs have on DMA ?

DMA Configurations (1) • Single Bus, Detached DMA controller • Each transfer uses bus DMA Configurations (1) • Single Bus, Detached DMA controller • Each transfer uses bus twice — I/O to DMA then DMA to memory • CPU is suspended twice

DMA Configurations (2) • Single Bus, Integrated DMA controller • Controller may support >1 DMA Configurations (2) • Single Bus, Integrated DMA controller • Controller may support >1 device • Each transfer uses bus once —DMA to memory • CPU is suspended once

DMA Configurations (3) • Separate I/O Bus • Bus supports all DMA enabled devices DMA Configurations (3) • Separate I/O Bus • Bus supports all DMA enabled devices • Each transfer uses bus once —DMA to memory • CPU is suspended once

I/O Channels • I/O channels are processors dedicated to I/O e. g. 3 D I/O Channels • I/O channels are processors dedicated to I/O e. g. 3 D graphics cards • CPU instructs I/O controller to do transfer • I/O controller does entire transfer from one or many devices • Makes transfers less visible to CPU • Improves speed —Takes load off CPU

I/O Channel Architecture I/O Channel Architecture

Interfacing Options • • • Parallel - PCI - SCSI Serial - RS 232 Interfacing Options • • • Parallel - PCI - SCSI Serial - RS 232 Local Networks - Ethernet Newer technologies - Fire. Wire - Infini. Band - USB Wireless - Blue. Tooth - Wi. Fi Automation - CAN

Intel 82 C 55 A Programmable Peripheral Interface Intel 82 C 55 A Programmable Peripheral Interface

Keyboard/Display Interfaces to 82 C 55 A Keyboard/Display Interfaces to 82 C 55 A

Layering – Example: OSI Network Layers International Standards Organization’s (ISO) Open Systems Interconnection (ISO) Layering – Example: OSI Network Layers International Standards Organization’s (ISO) Open Systems Interconnection (ISO) Model: • The Physical Layer describes the physical properties of the various communications media, as well as the electrical properties and interpretation of the exchanged signals. Example: this layer defines the size of Ethernet coaxial cable, the type of BNC connector used, and the termination method. • The Data Link Layer describes the logical organization of data bits transmitted on a particular medium. Example: this layer defines the framing, addressing and check-summing of Ethernet packets. • The Network Layer describes how a series of exchanges over various data links can deliver data between any two nodes in a network. Example: this layer defines the addressing and routing structure of the Internet. • The Transport Layer describes the quality and nature of the data delivery. Example: this layer defines if and how retransmissions will be used to ensure data delivery. • The Session Layer describes the organization of data sequences larger than the packets handled by lower layers. Example: this layer describes how request and reply packets are paired in a remote procedure call. • The Presentation Layer describes the syntax of data being transferred. Example: this layer describes how floating point numbers can be exchanged between hosts with different math formats. • The Application Layer describes how real work actually gets done. Example: this layer would implement file system operations.

Simple Example OF 7 Layer OSI Model Application Layer: Set of C Instructions, Set Simple Example OF 7 Layer OSI Model Application Layer: Set of C Instructions, Set of Data {I 0 I 1 I 2 …. IN Do D 1 D 2 … Dm} Presentation Layer: ASCII Coding {ASC {I 0 I 1 I 2 …. IN Do D 1 D 2 … Dm}} Session Layer: What process at computer x is communicating with what process at computer y {X 4 Y 6 {ASC {I 0 I 1 I 2 …. IN Do D 1 D 2 … Dm}}} Transport Layer: Guaranteed Transmission, sequentially numbered packets of 4096 bytes {GT 4 P 34 {X 4 Y 6 {ASC {I 0 I 1 I 2 …. IN Do D 1 D 2 … Dm}}} PCKSUM} Network Layer: Path through Network {N 23 N 53 {GT 4 P 34 {X 4 Y 6 {ASC {I 0 I 1 I 2 …. IN Do D 1 D 2 … Dm}}} PCKSUM}} Data Link Layer: Serial 256 bytes per frame {STRT T{N 23 N 53 {GT 4 P 34 {X 4 Y 6 {ASC {I 0 I 1 I 2 …. IN Do D 1 D 2 … Dm}}} PCKSUM}}CHKSM} Physical Layer: 9600 Baud, Coax cable - {Start {…. }Parity Stop}

Serial - RS 232 • UART (Universal Asynchronous Receiver & Transmitter) • Serial interface Serial - RS 232 • UART (Universal Asynchronous Receiver & Transmitter) • Serial interface on a chip • Historically very significant • After 30 years, still a standard

RS 232 Character transmission RS 232 Character transmission

UART Block Diagram UART Block Diagram

Connector Wiring – Null Modem Connector Wiring – Null Modem

UART Application UART Application

Ethernet • • CSMA/CD (Carrier Sense Multiple Access/Collision Detection) A local area network access Ethernet • • CSMA/CD (Carrier Sense Multiple Access/Collision Detection) A local area network access method in which contention between two or more stations is resolved by collision detection. When two stations transmit at the same time, they both stop and signal a collision has occurred. Each then tries again after waiting a predetermined time period. To avoid another collision, the stations involved each choose a random time interval to schedule the retransmission of the collided frame. To make sure that the collision is recognized, Ethernet requires that a station must continue transmitting until the 50 microsecond period has ended. If the station has less than 64 bytes of data to send, then it must pad the data by adding zeros at the end.

Bob Metcalf’s Ethernet Concept - 1976 Bob Metcalf’s Ethernet Concept - 1976

Network Reference model - Ethernet Network Reference model - Ethernet

Ethernet packet Ethernet packet

Ethernet block diagram Ethernet block diagram

IEEE 1394 Fire. Wire (Competitor to USB) • • • High performance serial bus IEEE 1394 Fire. Wire (Competitor to USB) • • • High performance serial bus Fast Low cost Easy to implement Also being used in digital cameras, VCRs and TV

Fire. Wire Configuration • Daisy chain • Up to 63 devices on single port Fire. Wire Configuration • Daisy chain • Up to 63 devices on single port —Really 64 of which one is the interface itself • Up to 1022 buses can be connected with bridges • Automatic configuration • No bus terminators • May be tree structure

Simple Fire. Wire Configuration Simple Fire. Wire Configuration

Fire. Wire 3 Layer Stack • Physical —Transmission medium, electrical and signaling characteristics • Fire. Wire 3 Layer Stack • Physical —Transmission medium, electrical and signaling characteristics • Link —Transmission of data in packets • Transaction —Request-response protocol

Fire. Wire Protocol Stack Fire. Wire Protocol Stack

Fire. Wire - Physical Layer • Data rates from 25 to 400 Mbps • Fire. Wire - Physical Layer • Data rates from 25 to 400 Mbps • Two forms of arbitration —Based on tree structure —Root acts as arbiter —First come first served —Natural priority controls simultaneous requests – i. e. who is nearest to root —Fair arbitration —Urgent arbitration

Fire. Wire - Link Layer • Two transmission types —Asynchronous – Variable amount of Fire. Wire - Link Layer • Two transmission types —Asynchronous – Variable amount of data and several bytes of transaction data transferred as a packet – To explicit address – Acknowledgement returned —Isochronous – Variable amount of data in sequence of fixed size packets at regular intervals – Simplified addressing – No acknowledgement

Fire. Wire Subactions Fire. Wire Subactions

Infini. Band • I/O specification aimed at high end servers —Merger of Future I/O Infini. Band • I/O specification aimed at high end servers —Merger of Future I/O (Cisco, HP, Compaq, IBM) and Next Generation I/O (Intel) • Version 1 released early 2001 • Architecture and spec. for data flow between processor and intelligent I/O devices • Intended to replace PCI in servers • Increased capacity, expandability, flexibility

Infini. Band Architecture • Remote storage, networking and connection between servers • Attach servers, Infini. Band Architecture • Remote storage, networking and connection between servers • Attach servers, remote storage, network devices to central fabric of switches and links • Greater server density • Scalable data centre • Independent nodes added as required • I/O distance from server up to — 17 m using copper — 300 m multimode fibre optic — 10 km single mode fibre • Up to 30 Gbps

Infini. Band Switch Fabric Infini. Band Switch Fabric

Infini. Band Operation • 16 logical channels (virtual lanes) per physical link • One Infini. Band Operation • 16 logical channels (virtual lanes) per physical link • One lane for management, rest for data • Data in stream of packets • Virtual lane dedicated temporarily to end transfer • Switch maps traffic from incoming to outgoing lane

Infini. Band Protocol Stack Infini. Band Protocol Stack