Summary
Highlights
Device drivers are responsible for managing I/O operations, providing a uniform interface to the kernel. Each device controller has a device driver. The operating system doesn't need to handle device-specific details. USB compatibility is a common approach, but specialized features may require custom device drivers.
The video introduces interrupt vectors, explaining their role in handling interrupts and operating system services. Interrupt vector 0 is reserved for divide by zero errors.Different designers exist, and routines related to Inter vector 0 has to be written. Interrupt service routines (ISRs) are discussed. Some interrupts are used by the computer, while others are for program development.
The storage structure is divided into main memory, secondary storage, and tertiary storage. Main memory is directly accessible by the CPU and is volatile. Secondary storage provides larger, non-volatile storage, such as hard disks. Hard disks are structured with logical tracks and sectors.
Hard disks are explained, including their structure of tracks and sectors. Disk controllers manage logical connections between devices and the computer. Solid-state drives (SSDs) are faster than hard disks but are still stable. Optical disks are also mentioned and tertiary storage is available. Tertiary storage has the largest capacity but slowest access time, using tape drives and magnetic tapes.
The basic unit of computer storage is the bit, which can be 0 or 1. A byte is 8 bits. The word size depends on the computer architecture and is not a fixed size. Throughput is measured in bytes. The video explains the approximations of megabytes and gigabytes.
The memory hierarchy is examined based on speed, cost, and volatility, from CPU registers (fastest, smallest) to tertiary storage (slowest, largest). Caching is used to copy information from slower to faster storage. The hierarchy includes registers, cache memory, main memory, and secondary storage.
Cache memory is introduced as a faster memory type between registers and main memory. It stores frequently accessed memory portions, reducing the need to access main memory. Cache memory is faster than main memory due to its access technology. More information about cache architecture is available in computer architecture books.
A typical computer system consists of CPUs and device controllers connected via a common bus. Device controllers manage specific device types. The device driver loads registers of the device controller to initiate an I/O operation. The device controller examines the contents of these registers and begins transferring the data.
Direct Memory Access (DMA) is introduced for transferring large amounts of data. Instead of interrupting the processor for each byte, the DMA controller transfers the entire data block directly to memory, and notifies the device driver about the completed operation. DMA controller makes multi programming possible and improves computer throughput.
Modern computer architectures are discussed, including the concept of threads and processes. In modern systems, CPUs execute multiple processes concurrently. The video discusses multiprocessor system architectures that have better throughput and reliability. The systems are split into symmetric and asymmetric multiprocessing, and the pros and cons of each are discussed.