stephen%hpdml93.hp.com@cunyvm.cuny.edu (12/06/89)
dawill@hubcap.clemson.edu (david williams) writes: > Hummm. I am in the process of hacking together a 50pin-to-25pin connector >for a StarDrive I recently got. The target drive (my roomate's) is a miniscribe >8425S. Is this drive differential? If not, how often is differential drive >used in the REAL world? I have a feeling that this would only be used on >really high-end drives, much as professional audio uses balanced connectors, and >consumer stuff only uses single-ended. Yup. Differential drives are mostly used on high-end systems. The SCSI bus uses +12V and -12V signal levels as opposed to +5v and GND used on Single-ended drives. Obviously, the differential drives are not as sensitive to say a 2V signal drop as would a single-ended drive. NOTE TO EVERYONE WHO IS WORRIED IF THEY HAVE A DIFFERENTIAL DRIVE ON THEIR AMIGA: All of the SCSI controllers that I know of for the Amiga use single-ended SCSI. You would *REALLY* know if you put a differential drive on a single-ended controller!! :-) I would *LOVE* to see standardization of cables (eg, SCSI means 50 pin cable, serial interface means DB-25 cable, etc.). Speaking of standard cables, what possessed Commodore to use a DB-23?!?!?!? :-) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Stephen Holmstead ...!hplabs!hpdmlge!stephen // Hewlett Packard Disk Memory Division \X/ Amiga Forever! "I remind you that humans are only a tiny minority in this galaxy." -- Spock, "The Apple," stardate 3715.6.
charles%hpcvca.cv.hp.com@cunyvm.cuny.edu (12/07/89)
> Hummm. I am in the process of hacking together a 50pin-to-25pin > connector for a StarDrive I recently got. The target drive (my > roomate's) is a miniscribe 8425S. Is this drive differential? No. SCSI is not differential. It merely (most of the time) interdigitates signals and grounds in the 50 wire ribbon cable. Sort of a poor man's differential drive. > If not, how often is differential drive used in the REAL world? I > have a feeling that this would only be used on really high-end > drives, much as professional audio uses balanced connectors, and > consumer stuff only uses single-ended. > Dave Williams > dawill@hubcap.clemson.edu Rarely. Don't worry about it. -- Charles Brown charles@cv.hp.com or charles%hpcvca@hplabs.hp.com or hplabs!hpcvca!charles or "Hey you!" Not representing my employer.
toweri@clinet.FI (Jukka Lindgren) (12/17/89)
Is anyone out there able to tell, how "standard" the "standard" SCSI-drives are? In my work, I am seeing a lot of >300Mb SCSI-drives, and sometimes I have wondered, if it would be possible to connect them to my Amiga. I have GVP 42Mb drive with GVP controller. It has an external connector (25 pins) and it draws its power from Amigas own power supply. Is the external connctor ONLY for Amiga-SCSI-drives, or is it universal? (More or less, at least...) -=(toweri)=- -- = VOICE: + 358 0 571789 || Any opinions expressed contain = = EMAIL: toweri@clinet.fi || * The Absolute Truth * = = or: ...!mcsun!santra!clinet!toweri || Therefore no disclaimers can be made = = SNAIL: don't bother... || (I KNEW you'd hate it !) =
lphillips@lpami.wimsey.bc.ca (Larry Phillips) (12/17/89)
In <1371@clinet.FI>, toweri@clinet.FI (Jukka Lindgren) writes: >Is anyone out there able to tell, how "standard" the "standard" >SCSI-drives are? Most modern SCSI drives support a common command set that allows them to be used interchangably. There are exceptions to this, and the only real way to tell is to either find someone who has tried a particular combo, or try it yourself. >In my work, I am seeing a lot of >300Mb SCSI-drives, and sometimes I >have wondered, if it would be possible to connect them to my Amiga. >I have GVP 42Mb drive with GVP controller. You have half the battle won, in that you have the GVP and the drives to try. I don't have a GVP host adapter, but have tried many drives on the ComSpec, 2090, 2090A, and HardFrame, with only one attempt being a failure (Maxtor LXT-100S on a HardFrame). > It has an external connector >(25 pins) and it draws its power from Amigas own power supply. Is the >external connctor ONLY for Amiga-SCSI-drives, or is it universal? >(More or less, at least...) There really isn't any such thing as an 'Amiga-SCSI-drive', unless you want to put that label on one of the 'packaged systems'. The 25 pin connector is Apple's idea of a SCSI interface connector (I sincerely wish the Amiga folks doing host adapters would supply a real 50 pin one instead). You will need a cable (get it from a Mac dealer, an external enclosure/pwr_supply/fan if you need to mount it externally. -larry -- " All I ask of my body is that it carry around my head." - Thomas Alva Edison - +-----------------------------------------------------------------------+ | // Larry Phillips | | \X/ lphillips@lpami.wimsey.bc.ca -or- uunet!van-bc!lpami!lphillips | | COMPUSERVE: 76703,4322 -or- 76703.4322@compuserve.com | +-----------------------------------------------------------------------+
monty@sagpd1.UUCP (Monty Saine) (12/20/89)
In article <1371@clinet.FI> toweri@clinet.UUCP (Jukka Lindgren) writes: >Is anyone out there able to tell, how "standard" the "standard" >SCSI-drives are? In MOST instances the hardware is "standard" (apple has a different reset handling method) your problem lies in which SCSI commands are implemented and how they are implemented. I am presently working on a SCSI project and have two devices that handle reporting of bad blocks entirely different. One uses the extended request sense command and the other uses a specific command to return the information. The point here is that the SCSI spec leaves a lot of "user definable" holes that are filled differently by different manufacturers. I guess the real answer to your question is the bus is standard but the information carried over it is not. Hope I helped Monty Saine > >In my work, I am seeing a lot of >300Mb SCSI-drives, and sometimes I >have wondered, if it would be possible to connect them to my Amiga. >I have GVP 42Mb drive with GVP controller. It has an external connector >(25 pins) and it draws its power from Amigas own power supply. Is the >external connctor ONLY for Amiga-SCSI-drives, or is it universal? >(More or less, at least...) >
rokkar@dsoft.UUCP (Paul Bell) (12/31/89)
As a registered GVP dealer, I can tell you this (if someone already has, apologies) -- the Impact and other hard drives by GVP are advertised as being able to chain 6 SCSI drives and 1 Apple/Mac SCSI. So, there must be some difference, but they do allow you one connect anyway. If it's a big drive, why not give it a shot. By the by, gang, I offer great prices on anything GVP. Happy to help anyone seeking to purchase drives, accelerators, etc. Paul Paul Bell & Assoc Inc. West Orange, NJ. 07052 (201) 736-3298: office Or, reach me at ddsw1!tronsbox!dsoft!rokkar or, uunet!tronsbox!dsoft!rokkar