--Initial program to run, this called bootstrapprogram.
--It initalizes all the aspects of system,from CPU registers to device controllers.
--The bootstrap program must locate andload into memory the OS kernel.
--The occurrence of an event is usuallysignaled by an interrupt.
--The interrupt must transfer control theappropriate interrupt service routine.
--The table of pointers is stored in lowmemory; these locations hold the addresses of the interrupt service routine forvarious devices, called Interrupt Vector(中断向量)
1.2.2 Storage Structure
--The CPU only loads instructions from thememory, exchange data with memory (the north birdge).
--All forms of memory contain an array ofwords; eachword has its own address.
--This section is easy.
1.2.3 I/O StructureD
--A device concoller maintains some local bufferstorage and some registers.
--The device is reponsible for moving databetween its device and the local buffer storage.
--OS has a device driver for each deviceconcoller.
--DMA (direct memory acess), exchange datastrightforward with memory.