Transcript Andrew-Kennedy-Kyle-Hunter-Mehdi-Tabdili-Chase-Crabtree

IBM OS/360
Andrew Kennedy
Kyle Hunter
Mehdi Tabdili
Chase Crabtree
System/360 Design Goals
• Extend to Commercial, Scientific, and Real
Time applications
• General method for using I/O devices that
differed in data rate, access and function
• Enable asynchronous operation of circuit,
storage and input/output components with
respect to each other (timesharing)
System/360 Series Overview
• Noteworthy Models:
– 25 ~ Small, specialized applications
– 67 ~ Virtual Memory, TSS/360  CP-67
– 85 ~ Cache Memory
• 3 Operating Systems:
– DOS/360
– OS/360
– TSS/360
OS 360 Principal Control
Program (PCP)
• Almost all operating systems prior to the OS/360
ran using stacked job batch processing (Pugh et
al., 1991).
• A single job ran at a time until completion.
• Scheduler level-1 – Allocated memory to one job
at a time.
• Supervisor level-1 – Initiated the execution of
each job in turn.
OS/360 MFT and MVT
•
MFT
– Could run a fixed number of
prioritized jobs concurrently.
– Memory was divided into
partitions.
– One job resided in each partition
of memory.
– Supervisor level-2 – Supported
the partitioning of memory and
multiprogramming among the
partitions.
– Scheduler level-2 – Permitted job
inputting with concurrent program
execution. Established a job
queue, and initiated the execution
of tasks according to priorities.
•
MVT
– Allocated dynamic memory
partitions for jobs which could
grow bigger or smaller during
execution.
– Supervisor level-3- Supported the
partitioning of memory
dynamically. Reallocated memory
when were jobs completed.
– Scheduler level-2
Time-Sharing Option (TSO)
• IBM did significant work on timesharing systems
in the 1960’s. Their experiments dealt with new
concepts such as the virtual machine.
• The Time-Sharing System (TSS) operating
system was released in 1967 but because it was
so expensive and many of IBM’s customers
used OS/360 it was abandoned.
• TSO software was released to run on OS/360
MVT.
What Was Done Right with
IBM OS/360
• Each part was tested separately to make
sure it was working properly.
• Introduction of Multi- Programming
• Job Control Language (JCL)
• TSO and “Time Sharing”
• Easier Input/Output operation
What Was Done Wrong with
IBM OS/360
• Managerial Differences caused a long
delay before its release.
• Many Bugs at the time of its release
• Complicated Installation process.
IBM OS 360 Deadlock Solutions
• Devices, volumes, and memory are
allocated in order on a per-job-step basis
• When Temporary file space can cause
deadlocks, operator intervenes and kills a
job
• Combination of Prevention and
Detection/Removal
Commercially Successful
• IBM’s OS/360 was very flexible in a way
such that it was built to be able to handle
any type of commercial or scientific task.
• Ex: A specific model was built for the North
America missile defense.
Economically Successful
• “$5 Billion Gamble”
• Within four weeks, IBM had 1,000 orders
for the computers and associated
peripherals. Two years later the company
had amassed 9,000 orders (Goff, 1999).
• They made the $5 billion back and made
much more over the years.