early computer systems

8/13/2019 Early Computer Systems

1/17

Computer Architecture WS 06/07 Dr.-Ing. Stefan Freinatis

Early Computer Systems

Vacuum tubes

A single group of people did all the workdesign, construction, programming, operating, maintenance

Programming in machine languageplugboard, no programming languages

Operating systemsFirst computer generation (1945 55)

Users directly interact with computer system

Programs directly interact with hardware

No operating system


Early Computer SystemsOperating systems

First computer generation (1945 55)

IBM 407 Accounting MachineElectro mechanical tabulator

Source: http://www.columbia.edu/acis/history/407.html

Wiring panel (plugboard)


2/17


Early Computer SystemsOperating systems

First computer generation (1945 55)

IBM 402 plugboard

Source: http://www.columbia.edu/acis/history/plugboard.html


Early Computer Systems

Vacuum tubes

A single group of people did all the workdesign, construction, programming, operating, maintenance

Programming in machine languageplugboard, no programming languages

Operating systemsFirst computer generation (1945 55)

Users directly interact with computer system

Programs directly interact with hardware

No operating system


3/17


Batch Systems

Transistors, Mainframe computers

First high level programming languagesFortran (Formula translation), Algol (Algorithmic language), Lisp (List Processing)

No direct user interaction with computerEverything went via the computer operators.

Users submitjob to operatorjob = program + data + control information.

Operator batched jobsComposition of jobs with similar needs

Operating systemsSecond computer generation (1955 65)


Batch SystemsOperating systems

Figure from [Ta01 p.9]

Structure of a typical FMS (Fortran Monitor System) batch job

Second computer generation (1955 65)


4/17


Batch SystemsOperating systems

Figure from [Ta01 p.8]

IBM IBM IBM

Batch job processing scence [Tanenbaum]



Batch Systems

Resident monitor program in memoryMonitor program loading one job one after another (from tape).

Operating systems

Monitor

program

job

Memory

Sequenced job inputJobs from tape or from card reader. Monitorprogram cannot selectjobs on its own.

One job in memory at a time

CPU often idlewaiting for slow I/O devices



5/17


Multiprogram Systems

DisksDirect access to several jobs on disk. Now the operating

system can select jobs (job scheduling).

Multiprogrammed Batch Systems

Operating systemsThird computer generation (1965 80)

OperatingSystem

job 1

Memory

job 2

job 3

job 4

Several jobs in memory at the same time

Operating system shares CPU time

among the jobs (CPU scheduling).

Better CPU utilization

Integrated Circuits


Multiprogram SystemsOperating systems

Assume program A being executed on a single-program

computer. The program needs two I/O operations.

Assume program B being executed on the same computer

at some other time. The program needs no I/O.

A1 A2 A3

I/O I/O

t

A A

CPU usage

over time

B1 B2 B3t

CPU usageover time


6/17


Multiprogram SystemsOperating systems

Total execution time on a single-program computer:

Total execution time on a multi-program computer:

Now assume program A and B being executed on a

multi-program computer.

B1 B2 B3A1 A2 A3

I/O I/O

t

A A

CPU usageover time


Multiprogram Systems

Multiprogram computers were still batch systems

Desire for quicker response timeIt took hours/days until output ready. A single misplaced comma could cause

a compilation to fail, and the programmer wasted half a day [Ta01 p.11].

Desire for interactivityUsers wanted to have the machine for themselves, working online.


Requests paved the way for timesharing

systems (still in third computer generation)


7/17


Time Sharing Systems

Direct user interactionMany users share a computer simultaneously. Terminals Host.

Multiple job execution with high frequent switchingOperating system must provide more sophisticated CPU scheduling.

Disk as backing store for memoryVirtual memory

Many jobs awaiting execution


Operating System

Swapping,

address translation,

protecting memory

(memory management)

Disk as input / output storageNeed for the OS to manage user data (file system management)


Time Sharing Systems

Assume program A and B as previously. Execution

on a time sharing system:Program B has finished

Time sharing is not necessarily faster. Compare to

the multiprogramming example:

Small time slices allow for interactivity (quasi parallel execution)

B1 B2 B3A1 A2 A3

I/O I/O

tCPU usageover time

I/O I/Ot

A A

CPU idleCPU usage

over time


8/17


Memory LayoutOperating

System

program 1

Memory

program 2

program 3

program 4

program n

program 5

program 6

Working

Memory

Time sharing system

OperatingSystem

job 1

Memory

job 2

job 3

job 4

Multi program system

Monitor

program

job

Memory

Batch system


Modern SystemsOperating systems

Fourth computer generation (1980 present)

Single-chip CPUs

Personal Computers

Real-Time Systems

Multiprocessor Systems

Distributed Systems

Embedded Systems

CP/M

MS-DOS, DR-DOS

Windows 1.0 ... Windows 98 / ME

Windows NT 4.0 ... 2003, XP

XENIX, MINIX, Linux, FreeBSD


9/17


Real Time Systems

Rigid time requirements

Hard Real Time

Industrial control & robotics

Guaranteed response times

Slimmed OS features (no virtual memory)

Soft Real Time

Multimedia, virtual reality

Less restrictive time requirements

RT System

RT System

Modern systems


Multiprocessor Systems

n processors in system (n > 1), tightly coupled

Resource sharing

Symmetric Multiprocessing

Asymmetric Multiprocessing

Each CPU runs identical copy of OS

All CPUs are peers (no master-slave)

Each CPU is assigned specific task

Task assignment by master CPU

User User User User

CPU CPU CPU CPU

Operating System

Operating System

User User User User

CPU CPU CPU CPU

Modern systems


10/17


Distributed Systems

Individual computers

Autonomous operation

Communication via network

Network Operating System

Modern systems

File Sharing

Message exchange

n computers/processors (n > 1), loosely coupled


Embedded Systems

Dedicated to specific tasks

Modern systems

Encapsulated in host deviceinvisible, usually not repaired when defect

Small in size, low energy

Sometimes safety-criticalautomotive drive by wire, medical apparatus

Custom(ized) operating systemLittle or no file I/O, sometimes multitasking,

no fancy OSs.


11/17


Resource ManagementOperating systems

File system management

Memory management

Creation and organization of a logical storage location where data (user

data, system data, programs) can be persistently stored in terms of files.

Assigning rights and managing accesses. Maintentance.

Process managementCreation of processes (programs in execution) and sharing the CPU

among them. Control of execution time. Enabling communication

between processes.

Device management.

Assigning memory areas to processes. Organizing virtual memory.

Low level administrative work related to the specifics of the I/O devices.

Translations, low level stream processing. Usually by device drivers.


Operating Systems

An operating system in the wide sense

is the software package for making a

computer operable.

The operating system in the narrow sense is

the one program running all the time on the

computer (the kernel).

It consists of several tasks and is asked for

services through system calls.

Imagesource:Wikipediaonkernel,English


12/17


Operating Systems

Operating system categories

Single User - Single Tasking

Single User - Multi Tasking

Multi User - Single Tasking

MS-DOS

Windows, MacOS

Multi User - Multi Tasking

CP/M

Unix, VMS


Computer Architecture

File System Management


13/17



Storage Media

Magnetic Disks

Files and Directories

File Implementation

Directory Implementation

Free BlockManagement

File System Layout

Disk Performance

Floppy Disks


Storage Media

Storage hierarchy

Figure from [Sil00 p.31]

low

high

accesstime

se

cond

ay

sto

rag

e

primarystorage


14/17


Storage MediaCost versus access time for DRAM and magnetic disks [HP06 p.359]

1ms 10ms

Flash


Storage Media

Store large amount of dataMuch more data than fits into (virtual) memory

Persistent store

The information must survive the terminationof the process creating or using it.

Concurrent access to dataMultiple processes should be able to access the data simultaneously.

Storage of data on secondary

storage media in terms of files.

Requirements for secondary storage


15/17



Storage Media

Magnetic Disks

Files and Directories

File Implementation

Directory Implementation

Free BlockManagement

File System Layout

Disk Performance

Floppy Disks


Magnetic DisksMagnetic disk drive principle

Figure from [Sil00 p.29]

Disk drive

Computer

diskcontroller

hostcontroller


16/17


Magnetic Disks

Sector: Smallest addressable unit on magnetic disk.

Data size between 32 and 4096 bytes (standard 512 bytes).

Several sectors may be combined to form a logical block. The

composition is usually performed by a device driver. In this way the

higher software layers only deal with abstract devices that all have

the same block size, independent of the physical sector size.

Such a block is also termed cluster.

A disk sectorFigure from [Ta01 p.315]

512 bytes


Magnetic Disks

Formatted Disk Capacity

= bytes per sector x tracks per cylinderx sectors per track

capacity of a track

capacity of one platter side

x cylinder

number of tracks on a platter

capacity of all platter sides = disk capacity

Capacity = 63 kB

CHS = (7, 2, 9), sector size: 512 byte

C = cylinder

H = Heads = tracks per cylinder

S =sectors per track


17/17


Magnetic Disks

Disk parameters for the original IBM PC floppy disk

and a Western Digital WD 18300 hard disk [Ta01 p.301].

(heads)

early computer systems

Documents