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Direct Memory Access (DMA) + (A mechanism to move data in/out/around memory without software intervention.)
Memory Mapping Extra + (A more detailed look towards practical memory mapping.;)
Arrays + (A note about programming arrays in C.)
Write Buffer + (A place to queue up (slow) output operations to avoid having to wait for them to complete.)
Memory Sizes + (A pragmatic look at the organisation of memory. Some terminology with which every computer scientist ought to be familiar.)
Interrupt Service Routines (ISRs) + (A procedure (or “method”) called by the hardware 'behind the scenes'. User applications are not directly aware of these.)
Dynamic Memory Allocation + (A process wants more memory; the OS tries to provide it.)
Race Conditions + (A race condition is normally a mistake, where two (or more) operations can complete in different orders - and thus leave different results - depending on issues such as the way threads are scheduled.)

Semaphores + (A signalling mechanism for access control in processes.)

Exercises + (A summary page for the various practical exercises for this module.)
Watchdog + (A system to facilitate crash recovery in embedded systems.)
Queues + (A widely used principle in operating systems (and elsewhere). Includes a look at implementation techniques.)
Memory Mapping Example + (A worked memory mapping example.)
Virtualisation + (An abstraction of some physical resource, typically for providing regularity in an interface or transparent sharing of the resource.)
Sockets + (An abstracted endpoint of a communications path.)
Synchronisation Barrier + (An animated demonstration of a synchronisation barrier.)
Timers + (An example I/O peripheral.)
I-nodes + (An example of filing system implementation)
FAT + (An example of filing system implementation.)
Paging States + (An example to help explain paging.)
Reset + (An exception which restarts the processor or system.)
Unix proc Exercise + (An exploration of some of the Unix internal data made human readable and pretending to be files.)
Security + (An important, all-spanning topic in comput … An important, all-spanning topic in computing. Within an operating system the primary concerns are to ensure that application processes can affect neither each other nor the operating system itself. This should include any leakage of illicit information.nclude any leakage of illicit information.)
Interrupts + (An interrupt is a form of exception where the hardware calls for a software service.)
What is an OS + (An operating system is a layer of software which lies between the application(s) program(s) and the hardware.)
Multiprocessors + (An overview of the implications - and additional problems - of having more than one hardware processor working in the same memory space at the same time.)
Hypervisor + (Another abstraction layer allowing several different operating systems to run concurrently on the same hardware without interfering with each other.)
Processor Privilege + (Any reasonably sophisticated processor wil … Any reasonably sophisticated processor will have more than one operating (privilege) mode. This lets the hardware detect that it is running a user application or trusted OS code and can prevent the former from seeing of changing any variables it does not specifically 'own'.changing any variables it does not specifically 'own'.)
Memory Mapping + (At its simplest, the (invisible) translation of the memory addresses a process wants to addresses of available, physical memory. I.e. this 'puts' the memory you bought in the places where you want to use it.)
Cacheability + (Caches are copies of data. This only works correctly under certain circumstances.)
Reentrancy + (Code is re-entrant if several threads can be running the same section of code at the same time. It should be clear that each thread's context is completely independent.)
Relocatable Code + (Code is relocatable if it can be moved to any address in memory and executed there successfully.)
Libraries + (Commonly used, probably optimised, application routines. Sometimes used to provide a more portable, user-friendly interface to an OS.)
Context Switching + (Context switching is changing from one running process to another. Typically this is done frequently to give the illusion of processes running concurrently)