ZinixOS

Our OS has been depolyed as an online appication. If you want to have have a try, please click the link.

C, x86 assembly, Operating System

This ambitious project is a Unix-like operating system built on the qemu virtual machine. It is the culmination of our operating system design course and is a testament to the hard work and dedication we put into this project. We developed this operating system from the ground up, ensuring that we could support a wide range of features and functionalities. We also added a number of unique features to make it stand out from other operating systems. Ultimately, this project was a great success and we are proud of the hard work and dedication we put into making it a reality. I also found great interest in operating system during this course

Basic functionalities: Implemented an operating system supporting fundamental features such as scheduling, interrupts, system calls, exceptions, and file systems.
Additionally, self-designed features were utilised to enhance the system, such as an implicit free list and slab cache to implement a virtual memory allocation system. Furthermore, advanced signals, speaker and hard-disk drivers were also implemented to the system, allowing for an increase in functionality and performance.

Show case of our OS

Two types of memory management

Fixed length memory allocation
Variable length memory allocation

Fixed length — Slab Cache

In this specific implementation, fixed length memory allocation is implemented by two parts, memory management unit and memory unit.
fixed length diagram:
        |memory management unit|  |memory management unit|  |memory management unit|  ..........    |memory unit|  |memory unit| |memory unit| .....
        |next|  --------------->  |next|  --------------->  |next|                                      ↑              ↑             ↑
        |ptr|---------------------|ptr|---------------------|ptr|---------------------------------------↑--------------↑-------------↑

Data structure: Linked list

Slab_Create ( name , size )
destroy , malloc , free
Automatically shrinks and grows
quick and fast to allocate and free
granularity: 1byte - 4kB-8 bytes

Variable length — Implicit free list

On the other hand, variable length memory allocation is implemented very similar to Linux's implicit free list design. 
A memory part consists of two parts, memory management unit and real useable memory unit.
Memory management units are held in a linked list to track each memory fragments have been allocated.
variable length diagram:
        |memory mangement unit| -> |memory mangement unit| -> |memory mangement unit| -> |memory mangement unit|
        -----------------------    -----------------------    -----------------------    -----------------------
        |                     |    |                     |    |                     |    |                     |
        |   useable memory    |    |   useable memory    |    |   useable memory    |    |   useable memory    |
        |                     |    |                     |    -----------------------    |                     |
        |                     |    -----------------------                               -----------------------
        |                     |
        -----------------------

Slab cache's implementation is based on fixed length memory allocation.

Data structure: Implicit free list

varmalloc( size )
flexible: can allocate any size
granularity: 1byte - 4MB

Memory allocation system and memory supevise system

Signal

Support users to set handler they define

Support sigreturn and set_handler syscall

Support five signals:

SIG_DIV_ZERO
SIG_SEGFAULT
SIG_INTERRUPT
SIG_ALARM
SIG_USER1

signal tests for our signal implementation

ATA Hard Disk Support & File System

Writable file system
```
write fname contents
```
Persistent Change (after reboot) by saving the change to the hard drive
How the file system is loaded and initialized:

Untitled

Speaker Driver

Key mapping:

(C3~E4) ZSXDCVGBHNJM,L.;/

(C4~G5) Q2W3ER5T6Y7UI9O0P[=]

Runs concurrently with any user programs & across terminals

part of the code for our ‘keyboard piano’