COSC240 • Operating Systems

Week 5: I/O Subsystems & Disk Scheduling

Examine device controllers, programmed I/O vs. memory-mapped I/O, APIC interrupts, DMA transfers, mechanical disk geometry, and RAID architectures.

📚 What You Will Learn
  • Core architectural mechanics and low-level data structures.
  • Kernel operational states, hardware interrupts, and protection boundaries.
  • Theoretical trade-offs, performance implications, and industry standards.
✅ What You Should Do
  • Review lecture notes and assigned textbook chapters.
  • Explore interactive pedagogical steppers and simulation modules.
  • Complete weekly tutorials, practical lab assignments, and review quizzes.
📂 Course Modules & Deep-Dive Texts
Module 01

I/O Hardware & Device Controllers

Explore device controller registers, data buffers, PMIO vs. MMIO hazards, and volatile memory fencing.

PMIOMMIODevice RegistersMemory Fencing
Module Overview →
Module 02

Interrupts, APIC & DMA Transfers

Study hardware interrupt vectors, top-halves vs. bottom-halves, MSI-X, and Direct Memory Access.

APICMSI-XSoftirqsDMA Controller
Module Overview →
Module 03

Disk Geometry & Arm Scheduling

Analyze platters, seek time, rotational latency, ZBR, and arm algorithms (FCFS, SSTF, SCAN, C-LOOK).

Seek TimeRotational DelaySSTFC-LOOK
Module Overview →
Module 04

RAID Storage Architectures

Evaluate RAID levels 0 through 6, XOR parity math, Galois Field P+Q codes, and MTTDL reliability modeling.

RAID 5RAID 6XOR ParityMTTDL
Module Overview →