Lecture 1: History and Installation of Linux/Unix

Serial Processing:
- Earliest computers lacked a real operating system.
- Console-only interaction: direct input to output.
- Two major challenges:
  1. Scheduling the use of the computer.
  2. Significant setup time for each run due to the absence of a resident system.
Simple Batch Systems:
- Developed in the mid-1950s at General Motors on the IBM 701 (IBSYS).
- Employed a layered system architecture.
- Interactive input/output.
- Utilized Job Control Logic (JCL) to handle job scheduling and execution.
Multi-programmed Batch Systems:
- Employed Multiprogramming/Multitasking, enabling multiple programs to reside in memory concurrently.
- Allowed programs to leverage idle CPU time.
Time-Sharing Systems:
- Used when iteration was required.
- Enabled multiple users to interact with the system simultaneously through terminals.
- With $N$ users, each user gets approximately $1/N$ of the CPU time.
- First used by the IBM 709 (1961) with CTSS developed at MIT.

Operating systems require structure due to concurrent process interactions.
Important to differentiate between policies and mechanisms in OS design:
- Policy: Defines what should be done.
- Mechanism: Defines how it should be done.
Policies are more susceptible to change over time.
Separating mechanisms from policies ensures that policy changes do not necessitate mechanism changes, and vice versa.
Without separation, altering policies might demand a complete redesign.

Also known as the central processing unit (CPU).
Represents the architecture upon which the Operating System is built.
The integer accumulating register's bit size determines the processor's bit size.
The size of the Data bus is not the processor size.
The size of the address bus of the processor and memory unit determines the maximum accessible memory.

Identifying the processor is crucial for selecting compatible applications and OS versions.
The assertion that 64-bit is always faster is not universally true.