RAM 6.0 BUX II Series Guía de usuario descargar pdf (Pagina 25)

7. Devices

DMA Controllers

DMA controllers can free the processor of lengthy copies to I/O devices or

off-board memory and may optionally be used by SCSI device drivers.

Reset Button

A reset button should be provided that is functionally equivalent to a power-on

reset. If operating in a bus-full environment, the reset signal may need to be

propagated to the bus.

Abort Button

The ability to generate a non-maskable-interrupt (NMI) allows the user to retake

control from a wayward interrupt-bound processor, without resetting the whole

board.

DIP Switches

Selection of addressing and interrupts is more convenient with DIP or rotary

switches than with jumpers. Software-readable DIP switches (jumpers) are an

advantage during configuration.

User LEDs

LEDs are useful debugging tools, especially on single-board computers. They

allow for quick visual inspection of a board to verify its functionality. With a row

of LEDs, information such as error codes can be displayed.

Physically, the LEDs should be in an easily visible place such as a front panel.

Programmatically, the LEDs should be in an easily visible place so that not much

board initialization needs to be done before the LEDs can be used. For example,

putting the LED registers on a subordinate bus is a bad idea since it prevents the

LEDs from being used until the bus is configured.

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RAM 6.0 BUX II Series Guía de usuario Pagina 25