Below Your Program

Alexander Nelson

January 15, 2020

University of Arkansas - Department of Computer Science and Computer Engineering

Below Your Program

Application Software – Written in

high-level language

System Software

• Compiler – Translate HLL to

Machine Code

• Operating System – Service Code

• Handle I/O

• Manage memory/storage

• Schedule tasks/IPC

Hardware – Processor, Memory, I/O

Controllers1

1Slide content provided by book authors

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Levels of Program Code

High-Level Language – Level of

abstraction close to problem domain

Provide productivity and portability

through abstraction

Assembly Language – Textual

representation of instructions for

given architecture

Hardware Representation – Binary

encoded instructions/data

2

Components of a Computer

Five basic components of

a computer:

• Input

• Output

• Memory

• Datapath

• Control

3

Input/Output

Input/Output facilitate interactions with people/things

e.g.

• Screen - Output

• Touchscreen - Both

• Mouse/Keyboard/Touchpad – Input

• Wireless Radio (Wi-Fi/BT/Cell) – Both

Controller for I/O Devices may have direct memory addressibility

(DMA)

4

LCD Rasterize

5

Opening the Box – Apple iPad 2

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Opening the Box

Apple A5 Processor, 16GB Flash Memory, Power management

TI Touchscreen Driver, Power management IC

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Inside the CPU – Apple A5

12.1x10.1mm Integrated

Circuit

45nm transistor process

Dual-core ARM processors

PowerVR GPU w/ 4

datapaths

2x256MiB DRAM

interfaces = 512MiB

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Inside the CPU – Apple A9X

12 GPU Cores!

8x512MiB DRAM (DDR4)

interfaces = 4GiB

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Abstractions

Instruction Set Architecture – Hardware/software

interface

Need to know what a chip can do

Allow identical software to run on different hardware

Cache Memory – Small, fast memory as buffer for

larger DRAM

Datapath is important as abstraction

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A Safe Place for Data

Volatile vs. Nonvolatile Memory

Volatile = able to change rapidly/unpredictably

Volatile in memory = Does not persist through power loss

Main Memory – Typically volatile, high level of memory hierarchy

Secondary Memory – Typically nonvolatile, lower level of memory

hierarchy

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A Safe Place for Data

SRAM/DRAM – Main Memory

Magnetic Disk, Flash Memory – Secondary Memory

Access times:

• SRAM = ˜10ns

• DRAM = ˜100ns

• Flash = ˜10,000ns

• Magnetic Disk = ˜9,000,000ns

Flash & Magnetic Disk wear out over time

Must control # of writes

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Cost Per Bit

2

2https://www.cs.utexas.edu/users/mckinley/352/lectures/21.pdf

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Communicating with other Computers

Different access technologies

• LAN – Local Area Network (Ethernet)

• WAN – Wide Area Netowrk (Internet)

• Wireless Network (WLAN/WWAN) – Wi-Fi/BT/Cellular

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