1. What is an Operating System? A historical Perspective
CSCE 410/611 Operating Systems
What is an Operating System?
Utilities? APIs? Services?
Brief historical journey
Operational definition
Historic Perspective

2. First-Generation Computers (1949-1956)
CSCE 410/611 Operating Systems
First-Generation Computers ( )
Re-Wiring the ENIAC with a new program (U.S. Army)
Historic Perspective

3. First-Generation Computers (1949-1956)
CSCE 410/611 Operating Systems
First-Generation Computers ( )
EDVAC (Ballistic Research Laboratory)
Historic Perspective

4. First-Generation Computers (1949-1956)
CSCE 410/611 Operating Systems
First-Generation Computers ( )
“The IBM-701 meets a future President” (IBM)
Historic Perspective

5. First-Generation Computers (1949-1956)
CSCE 410/611 Operating Systems
First-Generation Computers ( )
Single user writes program, operates computer through console.
Absolute machine language.
I/O devices
Development of libraries; device drivers
Relocatable code
memory space
user program area
libraries & dev.drivers
rest of user program area
Historic Perspective

6. Second-Generation Computers (1956-1963)
CSCE 410/611 Operating Systems
Second-Generation Computers ( )
UNIVAC at the Census Bureau
Historic Perspective

7. Second-Generation Computers (1956-1963)
CSCE 410/611 Operating Systems
Second-Generation Computers ( )
Observation: Efficient operation of computing infrastructure is critical!
Need to reduce setup time!
Solution:
Separate programming from operation
Move programming off-line
Automate Load/Translate/Load/Execute process
Computer Operator
Batch Operation
Monitor Programs
Historic Perspective

8. Second-Generation Computers (1956-1963)
CSCE 410/611 Operating Systems
Second-Generation Computers ( )
Separate programming from operation:
Automation:
“Job Entry Control”
$$ JOB JNM=JOB1,DISP=K,CLASS=2
$ FTN
<Program>
$ LOAD
$ RUN
$ DATA
<Data>
$$ EOJ
$$ JOB JNM=JOB2,DISP=K,CLASS=2
<Next job>
<...>
Punch card (public domain)
IBM 705 at Texas A&M University
(Cushing Memorial Library and Archives)
job sequencer and loader
memory space
control card interpreter
libraries & dev.drivers
Monitor
user program area
user program area
rest of user program area
device drivers
Historic Perspective

9. Second-Generation Computers (1956-1963)
CSCE 410/611 Operating Systems
Second-Generation Computers ( )
Separate programming from operation:
Observations:
Monitor loads and executes user programs.
Monitor stays resident in memory.
Misbehaving user program can affect execution of subsequent user programs.
Punch card (public domain)
Need to protect Monitor memory from user program!
IBM 705 at Texas A&M University
(Cushing Memorial Library and Archives)
job sequencer and loader
memory space
control card interpreter
Monitor
libraries & dev.drivers
user program area
user program area
rest of user program area
device drivers
Historic Perspective

10. Third-Generation Computers (1964-1973)
CSCE 410/611 Operating Systems
Third-Generation Computers ( )
Ken Thompson (sitting) and Dennis Ritchie at the PDP-11 (Peter Hamer)
Historic Perspective

11. Third-Generation Computers (1964-1973)
CSCE 410/611 Operating Systems
Third-Generation Computers ( )
Observations:
I/O devices are very slow.
I/O operations are very expensive.
Chronology of an I/O operation:
Zzz..
CPU J2 J4 J3 J5
I/O
I/O operation
Multiprogramming: Use idle time created by self-suspension to execute other workloads.
Historic Perspective

12. Third-Generation Computers (1964-1973)
CSCE 410/611 Operating Systems
Third-Generation Computers ( )
Multiprogramming:
CPU
I/O
I/O operation J2 J3 J4 J5
We need to ...
... have several programs ready to execute.
... keep several programs in memory.
memory space
Monitor
user program area
libraries & dev.drivers
user program area
Job1
rest of user program area
Job2
Job3
Job4
Historic Perspective

13. Third-Generation Computers (1964-1973)
CSCE 410/611 Operating Systems
Third-Generation Computers ( )
New issues with Multiprogramming:
How to schedule the jobs?
How to allocate memory to the jobs?
How to protect jobs from each other?
memory space
Monitor
user program area
libraries & dev.drivers
Job1
user program area
rest of user program area
Job2
Job3
Job4
Historic Perspective

14. CSCE 410/611 Operating Systems
Time Sharing (mid 1960s on)
Fernando Corbato with MIT’s CTSS IBM (MIT Museum)
CTSS = Compatible Time Sharing System
Historic Perspective

15. CSCE 410/611 Operating Systems
Time Sharing (mid 1960s on)
Remote interactive access to computer: “Computing as Utility”
How?
OS interleaves execution of multiple user programs with time quantum
CTSS (1961): time quantum 0.2 sec
New aspects and issues:
User “owns” machine: we need a persistent storage service (file systems)
Multiple users access machine: we need to protect resources (e.g., passwords!)
More programs than memory can handle: virtual memory
Users are impatient: we need sophisticated process scheduling
Advent of systematic techniques for designing and analyzing OSs.
Historic Perspective

16. CSCE 410/611 Operating Systems
Time Sharing (mid 1960s on)
Computing as Utility:
“If computers of the kind I have advocated become the computers of the future, then computing may someday be organized as a public utility just as the telephone system is a public utility... The computer utility could become the basis of a new and important industry.”
— John McCarthy, speaking at the MIT Centennial in 1961
Historic Perspective

17. CSCE 410/611 Operating Systems
More recently...
PCs, Pi, Arduino
History repeats itself
Parallel systems
Resource management
Fault tolerance
Real-Time Systems
Computing on a deadline
Secure Systems
Distributed Systems
Communication
Resource sharing
Coherency
Privacy?
Virtualization
an old idea
Cloud computing
Data Centers
Historic Perspective

18. What is, then, an Operating System?
CSCE 410/611 Operating Systems
What is, then, an Operating System?
The OS controls and coordinates the use of system resources.
Resource control and coordination has two goals:
Primary goal: Provide a convenient environment for a user to access the available resources (CPU, memory, I/O)
Provide appropriate abstractions (files, processes, ...)
Secondary goal: Ensure efficient operation of the computer system.
Historic Perspective

19. What is, then, an Operating System?
CSCE 410/611 Operating Systems
What is, then, an Operating System?
A convenient environment for a user to access ...
Ensure efficient operation of ...
Resource Management approaches
Transforming: Create virtual substitutes that are easier to use.
Multiplexing: Create the illusion of multiple resources from a single resource.
Scheduling: “Who gets the resource when?”
Historic Perspective

20. Summary: What is an Operating System?
CSCE 410/611 Operating Systems
What is an Operating System?
Brief historical journey
The OS controls and coordinates system resources.
Historic Perspective