About

CIMC is a 16-bit, loosely PC/x86 based redstone computer in Minecraft. The project aims to be as scalable as possible.

Architecture

The computer uses our own cx16 architecture.

Hardware features

• 16-bit CPU:

  • 4 general-purpose registers
  • Arithmetic operations
    • Add, subtract, multiply (wit 32-bit output!), divide, AND, OR, XOR, shift left, shift right
    • Reserved: Floating point !!
  • Stack
  • Simple x86 paging based virtual memory (64 KiB addressable memory, 512 B pages)
  • 16 I/O ports, 16-bit parallel bus
  • 8 external interrupts
  • CPU exceptions
  • 2 user accessible interrupts
  • 384B built-in BIOS ROM
  • CPU identification (CPUID)

• 7.625 KiB (7808 B) of RAM

• Chipset

  • 256 I/O ports
  • 16 IRQs
  • 16-bit parallel I/O bus
  • Special fast I/O bus ("Fast I/O")
  • Full DMA system

• Graphics adapter and display

  • Monitor (128x64, redstone lamp)
  • Text mode with ability to load custom font

• Mass storage (64 KiB)

  • 8 parallel 8 KiB-blocks "partitions" (effectively 7, one is for name registry)
  • Filesystem acceleration with directory structure
  • A maximum of 512 files (65535 IDs)
  • 12-character names (the last character is for extension)

• Sound adapter

  • 256 sound blocks for each speaker
  • A maximum of ?? parallel channels
  • 3-Speaker Dynamic Sound Distribution (DSD) for minimizing delays
  • 32B shift buffer for each channel

• (Almost) full keyboard (QWERTY)

  • Caps Lock, Alt, Control, Shift control keys

• Miscellaneous

  • Programmable Interval Timer (PIT)
  • Programmable interrupt controller (PIC), with interrupt masking
  • Real Time Clock - for querying MC time
  • Device Info (DI) interface used to detect and query device capabilities
  • Power Management Interface (PMI) for managing power state.
    • Support for Shutdown & Reboot.
    • Support for Power & Reset Buttons
    • Support for Power & HDD "LEDs"

• Additional features ;)

  • Full-pledged chassis
  • CPU and chassis fan
  • Network adapter

Software features

• BIOS / Bootloader
  • Ability to load kernel from file (thanks to FS acceleration)
• Simple operating system (VERY loosely Unix-based)
  • Up to 3 processes (shell, command, worker) + kernel, not preemptive for now
  • File descriptors (up to ?? per process)
  • Standard streams
  • Simple shell with Unix-like commands
• Applications
  • Text editor
  • Calculator
  • Paint
  • Hex editor
  • Some game
  • CIMC demo, showing various features of the computer.

Formats

See spec/OS/os-extensions.txt for details.

• Font, up to 256 characters (.ttf)
• Sound, up to 32B per channel (.mp3, .sig)
• Graphics, up to 16x16 (.cgr)
• Animation, up to 16x16, 8 frames (.gif)
• Executable - "normal" executable, library, object file (.exe, .obj)
• ASCII (.txt, .msg, .cpp, .sh, .asm)

Development features

• NOTE: Currently all development software works only on Linux (Tested on Ubuntu 20.04)

• Full cx16 emulator -- WIP

• Compiler/toolchain (C-based) -- WIP

• Font generator (from image file) -- TODO

• Sound generator (from MIDI) -- TODO

• Full specification of entire architecture -- WIP

Optimization ways

Because the worlds starts to lag, we must to find out a way a minimize it.

Possible ways are:

• Some no-lag plugin
• Custom MC server/MC client?

Links

https://wiki.osdev.org/Main_Page - info about creating operating systems
http://www.maverick-os.dk/FileSystemFormats/FAT12_FileSystem.html - FAT12 specification
https://software.intel.com/content/dam/develop/public/us/en/documents/325462-sdm-vol-1-2abcd-3abcd.pdf - Full spec of x86