On Fri, Oct 24, 2003 at 09:43:38AM +0100, Tony wrote: > Hi, > > Good idea. I have done this now. Went and downloaded the manual > and there are two DIP switches that are relevant. I quote from > the manual: > > ------- > Data Compression (switches 1 and 2) > > If switch 1 is ON (default), HW data compression is enabled. If > switch 1 is OFF, HW data compression is disabled. > > If dip switch 2 is ON (default), then SCSI commands can be used > to enable or disable HW data compression. To prevent HW data > compression from being enabled or disabled by SCSI commands, set > DIP switch 2 to OFF > ------- > > That all sounds pretty straight forward. I turned dip switches 1 > & 2 OFF so that HW compression is disabled and can't be turned > on again by the software. > > I would hope that if I have physically set these switches, that > even putting in a tape that was previously written on with > compression enabled could not over-ride the DIP switch settings. >
I would not make that assumption. The manual description of the effect of SW-2 refers to the ability of software to change the compression setting, not the ability of the hardware itself to change the setting. Otherwise you would not be able to 'read' tapes previously compressed. Certainly not a desireable trait. I would 'expect', but not assume, that after switching to HW compression ON during a read, subsequent writes would still be compression OFF if SW-2&1 and is off. But one never knows does one? BTW the manual for my drive has similar dip switch settings. SW-1 is refered to as the "power on state". So the drive must be power cycled to restore that state after a switch change. SW-2 is described as enabling/disabling software control of the compression state. But it doesn't say the hardware can't change the state. -- Jon H. LaBadie [EMAIL PROTECTED] JG Computing 4455 Province Line Road (609) 252-0159 Princeton, NJ 08540-4322 (609) 683-7220 (fax)
