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to enable smooth playing of dvd discs DMA MUST BE ENABLED.
when dma is not enabled the signals are processed by the cpu, (they dont need to be). processing takes up a lot of resources and generally the cpu cant keep up with the demand on it, even a modern powerful one will struggle to cope.i have a 1gig athlon and it makes the machine jump like crazy if DMA is not enabled, so enable dma for your dvd drive.
i wouldnt worry about the digital connection at ths stage its proberbly not that.
i would start by disconnecting the drive completely from the pc. then restart and remove all the software from the machine. if there is an entry in device manager for the drive remove it. then power down the pc.
take the new dvd drive and ensure the jumper settings on the back are set to master. (this is usually the default factory setting)
reconnect the dvd drive. most dvd drives usually have three cable connections to them.
1, power lead
2, ide cable,
3, audio cable
connect the three cables, the power lead and audio leads will only connect one way round, so you should be ok, but dont force them. ensure that the individual wires in the connection are secure in the plastic block,( i have come across these sometimes where they push out and dont make a proper conection).
it may be possible to get the IDE cable connected around the wrong way,(some have locating slots, some dont). remember the edge of the ribbon cable marked with a red/black trace refers to pin one on the connection. pin one should be clearly marked on the dvd drive. connect the IDE cable and ensure that it is securly connected to the mobo as well. if the cable has become disconnected the same rule applies, red trace to pin one on the mobo.
most mobos will usually have at least two IDE channels, ensure that the IDE cable from the dvd is connected to its own IDE channel (HDD on one, dvd on one).
ok so you are all connected up.
restart the computer and wait to see what happens, if all is well win 98 will detect and install the driver for it. (dont worry most dvd drives only require the generic driver supplied by windows, its proberbly already stored in your winsys directory).
all you need to do then is reintall your software to veiw your dvd films.
if you need it win98 has its own basic software player stored in cab17.
i hope this helps,
brendan