--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.

--Hierarchy 存储山

--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.