PandOS

Shahir Ahmed and Boosung Kim
Operating Systems Project – PandOS Kernel for uMPS3

Overview

PandOS is a custom operating system developed for the uMPS3 emulator, a 3000 RISC architecture simulator. This project implements key OS functionalities such as:

• Time-sharing & Multiprogramming – Running multiple processes concurrently.
• Process Scheduling – Using the round-robin algorithm for CPU time allocation.
• Device Interrupt Handling – Managing hardware interaction through interrupts.
• System Call Management – Supporting I/O, process creation, and termination.
• Trap Handling – Managing runtime errors to maintain system stability.
• Deadlock Detection – Preventing system-wide resource locks.
• Virtual Memory with Paging – Enabling efficient memory management via TLB paging.

For a more detailed explanation of the project, see the Technical Report.

Implementation Phases

Phase 1: Queue Management

• Implemented Process Control Blocks (PCB) and Active Semaphore Lists (ASL).
• Designed linked list structures for process scheduling and synchronization.

Phase 2: Kernel Development

• Added round-robin scheduler, interrupt handlers, and system calls for I/O and process management.
• Integrated passeren (P) / verhogen (V) operations for mutual exclusion.

Phase 3: Support Level

• Implemented paging and virtual memory with TLB address translation.
• Enabled eight concurrent user processes with swap pool management.

Setup & Compilation

1. Compile the PandOS Kernel

Navigate to the pandos/phase3 directory and run:

make

To clean up previous builds:

make clean

2. Set Up uMPS3 Emulator

1. Launch uMPS3:

   umps3
   

2. Create a new machine configuration:

   • Set directory to pandos/phase3
   • Adjust general settings:
     • TLB Size: 32
     • TLB Floor: 0x80000000
     • RAM Size (Frames): 128

3. Configure Flash Drives:

   • Assign each flash drive to a corresponding user process (see Technical Report for details).

4. Enable all 8 terminals under the "Terminals" tab.

3. Run PandOS

1. Power on the emulator.
2. Open Windows > Terminal 0-7 to observe output from all eight user processes.
3. Click the Run (▶) button.

Testing

To test swapStress.c:

1. Modify Makefile in pandos/phase3/resources/testers:
   • Replace terminalTest5.umps with swapStress.umps
2. Recompile and run:

make
umps3

Reflection

This project deepened our understanding of process synchronization, virtual memory, and low-level OS design. Implementing paging with TLB and handling device interrupts provided valuable experience in kernel development.

Technical Report

For a full breakdown of implementation details, see PandOS-Implementation-Report.pdf.

Authors

Shahir Ahmed & Boosung Kim