History of device configuration Plug and play

ibm 402 accounting machine control panel wiring. control panel labeled profit & loss summary .

in beginnings of data processing technology, hardware collection of modules, , functions of modules had linked accommodate different calculating operations. linking done connecting wires between modules , disconnecting others. many mechanical data processing machines, such ibm punched card accounting machines, calculating operations directed use of quick-swap control panel wired route signals between module sockets.

as general purpose computing devices developed, these connections , disconnections instead used specify locations in system address space expansion device should appear, in order device accessible central processing unit. if 2 or more of same type of device installed in 1 computer, necessary assign second device separate, non-overlapping region of system address space both accessible @ same time.

apple ii serial interface card required cutting , soldering reconfigure. user cut wire trace between >< cones @ x1 , x3 , solder <> cones @ x2 , x4. located vertically near center of board.

some microcomputing devices such apple ii required end-user physically cut wires , solder others make configuration changes. changes intended largely permanent life of hardware.

as computers became more accessible general public, need developed more frequent changes made computer users unskilled using soldering irons. rather cutting , soldering connections, configuration accomplished jumpers or dip switches.

however, process of configuring devices manually using jumpers or dip switches, quite difficult, , there no forgiveness technical inexperience. incorrect settings render either whole system or expansion device or partially inoperable. settings such interrupts (irq) or direct memory access (dma) required knowledge of configuration had been manually assigned other devices, settings main system may have been using. system might still have seemed work incorrect setting, until irq or dma needed , entire system froze , needed reset.