ENIAC1943-1946Electronic Numerical Integrator And Computer18.000
vacuum tubes30 tones150 m2140 kWDecimal5000 additions per
secondJohn von Neumann
Computer Types
Abstract layers of computer useUser
InterfaceApplicationOperating SystemDrivers, BIOSHardware
Abstract layers of computerProblem-oriented language levelLevel
5Translation (compiler)Assembly language levelLevel 4Translation
(assembler)OS machine levelLevel 3Partial interpretation (operating
system)Instruction set architecture levelLevel 2Interpretation
(mprog) or direct executionMicroarchitecture levelLevel
1HardwareDigital Logic LevelLevel 0
Computer Structure Data BusAddress BusControl Bus
PC structurePower SourceCircuit Board -
MotherBoardProcessorMemory SlotsChipsRear/Front ConnectorsSockets
where the edge connectors of I/O boards can be inserted
Device ControllersThe job of a controller is to control its I/O
device and handle bus access for it.When a program wants data from
the disk for example, it gives a command to the disk controller,
which then issues seeks and other commands to the drive. When the
proper track and sector have been located, the drive begins
outputting the data as a serial bit stream to the controller. The
controller breaks the bit stream up into units and sends them
further.A controller that reads or writes data to or from memory
without CPU intervention performs DMA (Direct Memory Access). When
the transfer is completed, the controller normally causes an
interrupt, forcing the CPU to suspend running its current program
and start running a special procedure, called an interrupt handler,
to check for errors, take any special action needed, and inform the
operating system that the I/O is now finished. When the interrupt
handler is finished, the CPU continues with the program that was
suspended when the interrupt occurred
Later PC Structure
Main MemoryVideo Controller
CPUMonitorSCSI ControllerSCSI chain
USB Controller
USB chain
Network ControllerNetwork PCI Bus
PCI Bridge
ISA Bridge ISA BusPrinter ControllerModemSound CardMemory
Bus
