david@david.UUCP (David A. Roth) (02/11/91)
Has anyone heard of a interface that allows a MAC to be backed-up on
at DAT(Digital Audio Tape), something like the old VCR backup systems
with Apple IIs.
I've heard about the DAT backup offered with DigiDesign but I don't
think that allows complete archive of the system just the soundfiles.
Thanks in advance.
David
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David A. Roth uunet!abvax!osu-cis!david!david
From CompuServ: send >internet:david@david.uucp
------------------------------------------------------------------------yahnke@vms.macc.wisc.edu (Ross Yahnke, MACC) (02/13/91)
In article <789@david.UUCP>, david@david.UUCP (David A. Roth) writes... >Has anyone heard of a interface that allows a MAC to be backed-up on >at DAT(Digital Audio Tape), something like the old VCR backup systems >with Apple IIs. MaxStream, among others, offers a very fast (8 megs/min?) tape backup that uses 8mm 'video' cassettes >>> yahnke@macc.wisc.edu <<<
mingo@well.sf.ca.us (Charles Hawkins Mingo) (02/17/91)
In article <789@david.UUCP> david@david.UUCP (David A. Roth) writes: >Has anyone heard of a interface that allows a MAC to be backed-up on >at DAT(Digital Audio Tape), something like the old VCR backup systems >with Apple IIs. > >I've heard about the DAT backup offered with DigiDesign but I don't >think that allows complete archive of the system just the soundfiles. I don't think one can use a conventional audio DAT deck for data backups. There ARE archival tape units based on the DAT mechanism (one of them claims to be able to put 10Gb on one cassette), but audio DAT units lack a mechanism to permit the computer to externally control them. I know that VCR's *have* been used to back up macs, but the information density on a DAT means that several megabytes would be recorded/ played each second; the mac could only keep up with a DAT if it could turn the DAT on and off for millisecond intervals. It's a bit like how you can't use a conventional CD player to play CD-ROM's. You need a hardware interface to the deck's controller. -- ______________________________________________________________________________ Charlie Mingo Internet: mingo@well.sf.ca.us 2209 Washington Circle #2 mingo@cup.portal.com Washington, DC 20037 CI$: 71340,2152 AT&T: 202/785-2089
epan@jarthur.Claremont.EDU (Eric C. Pan) (02/17/91)
Charlie Mingo talked in his post about unusability of audio DATs for computer backup due to the lack of control. But what about Sony's L-control(?) , S-control(?) and Pioneer's control system. A lot of companies produce comp- onents that had control interfaces intended for control by a reciever/pre-amp . Are those usable from a computer-control standpoint? Eric p.s. I believe the 10mg/tape capacity Charlie quoted is based on hardware compression and not the "real" or "raw" storage capacity of DAT tapes.
bdugan@teri.bio.uci.edu (Bill Dugan) (02/17/91)
In article <23192@well.sf.ca.us> mingo@well.sf.ca.us (Charles Hawkins Mingo) writes: >[...] > It's a bit like how you can't use a conventional CD player to play >CD-ROM's. You need a hardware interface to the deck's controller. I have always wondered why CD-ROM drives are so expensive when compared to the consumer audio CD players. CD-ROM drives use the same mechanism, don;t need D/A converters, and all they really need is a SCSI card on-board. Am I spouting mixed-up untruth, or should CD-ROM drives cost $200? bill
nilesinc@well.sf.ca.us (Avi Rappoport) (02/17/91)
In article <789@david.UUCP> david@david.UUCP (David A. Roth) writes: >Has anyone heard of a interface that allows a MAC to be backed-up on >at DAT(Digital Audio Tape), something like the old VCR backup systems >with Apple IIs. See MacWEEK, February 12. They have a short thing on the current state of DAT backup. -- -- Help me justify my online bills: ask me EndNote questions, please! -- Avi Rappoport 2000 Hearst, Berkeley, CA 94709 nilesinc@well.sf.ca.us, 415-649-8176 Niles.Assoc on AppleLink fax: 415-649-8179
mingo@well.sf.ca.us (Charles Hawkins Mingo) (02/18/91)
In article <10851@jarthur.Claremont.EDU> epan@jarthur.Claremont.EDU (Eric C. Pan) writes: > > Charlie Mingo talked in his post about unusability of audio DATs for >computer backup due to the lack of control. But what about Sony's >L-control(?), S-control(?) and Pioneer's control system. A lot of companies >produce components that had control interfaces intended for control by a >reciever/pre-amp. Are those usable from a computer-control standpoint? Well, I'm no expert on the specifics of L-Control, S-Control, et al., but the reciever/pre-amp coordination system are usually only designed to do simple things like "start PLAY" or "REWind", not "advance to frame 08A3F1 and transmit the next sixty frames." A computer controller requires extremely precise control over the device, so that specific locations can be reliably accessed. It also usually needs some sort of error detection/ correction system, which audio DATs generally lack. (Audio DAT's have mechanisms to make errors less noticable, such as interpolation, but data DAT's have to eliminate errors completely.) And consumer DAT's *do* produce a lot of errors of the bit level. According to reports on the dat-heads mailing list, 2500 errors/second is not unheard of. This is not a problem for recording *music*, but data would be really corrupted by this. (The best DAT's have around 100 errors/second.) >p.s. I believe the 10mg/tape capacity Charlie quoted is based on hardware >compression and not the "real" or "raw" storage capacity of DAT tapes. Well, that was 10GB (GigaBytes), and there surely is some compression involved, but I've never seen a DAT data cassette system which offered less than 2GB. Remember that the PCM system involves around 1.5 million bits/ second of recording time, which suggests a "raw" data storage of 1.35GB on a 120min cassette. -- ______________________________________________________________________________ Charlie Mingo Internet: mingo@well.sf.ca.us 2209 Washington Circle #2 mingo@cup.portal.com Washington, DC 20037 CI$: 71340,2152 AT&T: 202/785-2089
mingo@well.sf.ca.us (Charles Hawkins Mingo) (02/18/91)
In article <27BDB6B4.17437@orion.oac.uci.edu> bdugan@teri.bio.uci.edu (Bill Dugan) writes: >In article <23192@well.sf.ca.us> mingo@well.sf.ca.us (Charles Hawkins Mingo) writes: >>[...] >> It's a bit like how you can't use a conventional CD player to play >>CD-ROM's. You need a hardware interface to the deck's controller. > >I have always wondered why CD-ROM drives are so expensive when compared to >the consumer audio CD players. CD-ROM drives use the same mechanism, don;t >need D/A converters, and all they really need is a SCSI card on-board. >Am I spouting mixed-up untruth, or should CD-ROM drives cost $200? It has to do with production quantity. Tens of millions of CD players are made each year; only a few tens of thousands of CD-ROM's (if that) are. When I purchased my first CD player in 1983 (an NEC 803CD), it cost $1250, and the cheapest available was a Denon for about $850. DAT decks involve the tape mechanism of a VCR, with the D/A converter of a CD player. Yet DAT's cost much more than a VCR and a CD player combined. Mind you, DAT prices are falling fast, and some speculate they'll cross the critical $500 price barrier, which is the threshold for widespread acceptance, based on the VCR and CD experience. -- ______________________________________________________________________________ Charlie Mingo Internet: mingo@well.sf.ca.us 2209 Washington Circle #2 mingo@cup.portal.com Washington, DC 20037 CI$: 71340,2152 AT&T: 202/785-2089
bill@bilver.uucp (Bill Vermillion) (02/18/91)
In article <23206@well.sf.ca.us> mingo@well.sf.ca.us (Charles Hawkins Mingo) writes: > It has to do with production quantity. .... > DAT decks involve the tape mechanism of a VCR, with the D/A converter >of a CD player. Yet DAT's cost much more than a VCR and a CD player combined. DAT decks involve the same principles as a VCR but their transport is unique. The only thing that uses DAT transports and DAT sized tape are DATS. No way to combine savings with other mechanical transports. -- Bill Vermillion - UUCP: uunet!tarpit!bilver!bill : bill@bilver.UUCP
hodas@saul.cis.upenn.edu (Josh Hodas) (02/19/91)
In article <27BDB6B4.17437@orion.oac.uci.edu> bdugan@teri.bio.uci.edu (Bill Dugan) writes: > >I have always wondered why CD-ROM drives are so expensive when compared to >the consumer audio CD players. CD-ROM drives use the same mechanism, don;t >need D/A converters, and all they really need is a SCSI card on-board. >Am I spouting mixed-up untruth, or should CD-ROM drives cost $200? > >bill Well, I don't think they are the same mechanism in general. Consider, how long does it take your CD player to seek from the beginning of a disc to the end. Most take at least a couple of seconds. Such a mechanism would be unacceptable for use with a CD-ROM where you want much higher access times. Now, there is one drive out, the portable from NEC, I forget its model number, which is low priced, and seems to use a traditional mechanism. It's average access time, however, is something like 1500ms, as compared to about 350ms for higher-end CD-ROM drives, like the Toshiba. Josh ---------------------------------------------------------------------------- Josh Hodas Home Phone: (215) 222-7112 4223 Pine Street School Office Phone: (215) 898-9514 Philadelphia, PA 19104 New E-Mail Address: hodas@saul.cis.upenn.edu
stanfiel@testeng1.misemi (Chris Stanfield) (02/20/91)
In article <10851@jarthur.Claremont.EDU> epan@jarthur.Claremont.EDU (Eric C. Pan) writes: > >p.s. I believe the 10mg/tape capacity Charlie quoted is based on hardware >compression and not the "real" or "raw" storage capacity of DAT tapes. I would have thought that the data capacity of a DAT tape would be similar to that of a CD. If I have got my math right, that would be (for tape that couls hold 1 hour of audio): sample rate = app. 50 kHz per channel, two channels, 8 bit coding (i.e. byte encoding) = 100,000 samples/sec*60*60 = 360 M samples, which is 360 Mb of data This is, of course, raw, unformatted capacity, but I don't see any reason why you shouldn't be able to get 256 Mb of data onto a tape. Am I missing something? Chris Stanfield, Mitel Corporation: E-mail to:- uunet!mitel!testeng1!stanfiel (613) 592 2122 Ext.4960 We do not inherit the world from our parents - we borrow it from our children.
mcohen@umbc5.umbc.edu (Mr. Mark Cohen; HONORS COL (U)) (05/13/91)
In article <27BDB6B4.17437@orion.oac.uci.edu> bdugan@teri.bio.uci.edu (Bill Dugan) writes: >In article <23192@well.sf.ca.us> mingo@well.sf.ca.us (Charles Hawkins Mingo) writes: >>[...] >> It's a bit like how you can't use a conventional CD player to play >>CD-ROM's. You need a hardware interface to the deck's controller. > >I have always wondered why CD-ROM drives are so expensive when compared to >the consumer audio CD players. CD-ROM drives use the same mechanism, don;t >need D/A converters, and all they really need is a SCSI card on-board. >Am I spouting mixed-up untruth, or should CD-ROM drives cost $200? > >bill You aren't too far from some of the lower-end type prices for CD-ROM's. If you take a look in the nearest DAK catalog, you will see that you can get the CD-ROM plus 6 full CD's for around $700. (I don't have the catalog with me, but it's around there.) I figure that a great deal of that is for the software (hey, lot's of people put lots of time into digitizing that stuff!!), but of course they advertise that as free discs from buying the CD-ROM. The only cost of the drive that you missed is the actual board for the computer and cable to hook it in (figure almost $100 for that). So, yes, CD-ROM's should be maybe $300-$400, but you can find the exact same thing for thousands more if you try hard enough. I got one of the CD-ROM's from DAK and I love it. (out about $700 but worth it), Mark MCOHEN@UMBC5.UMBC.EDU