test-drb

test-drb@ccmp.vtda.org

101090 discussions

by Innfogra＠aol.com

I bought 6 of these chips about 8 or 9 years ago, IIRC. However I have exhausted all of my resources to identify them at the moment. I would like to know what they are. The numbers are: IDT 7M624 S45C (Delta symbol) 8738G1 Pretty chip, 8 gold caps mounted on a large purple ceramic substrate. 40 pin wide DIP. 7/8 inch by 2 7/16 inch in size, large like a 68000 but not as long. Pictures at: http://members.aol.com/innfogra/idt624a1.jpg http://members.aol.com/innfogra/idt624a2.jpg Paxton Astoria, OR

23 years, 11 months

pdp 11/44 terminating UNIBUS

by huglhuglhugl＠gmx.net

Hi! Now that my pdp11/44 is talking to me (switched from current loop to rs232), i'd like to use it, of course. But i'm missing a unibus-terminator. Does someone have a spare one ? i do have some cards (unibus and qbus) to trade... btw. i live in Belgium / Europe. Or is there a way to make a unibus-terminator, AFAIK they only contain resistors. Did someone do this before, or maybe someone has scematics of a terminator ? regards, lothar. -- GMX - Die Kommunikationsplattform im Internet. http://www.gmx.net

23 years, 11 months

Tape dumping programs for Unix/Linux...

by cdl＠proxima.ucsd.edu

> From: Raymond Moyers <rmoyers(a)nop.org> > To: classiccmp(a)classiccmp.org > Subject: Re: Tape dumping programs for Unix/Linux... > Date: Thu, 2 May 2002 21:56:13 -0500 > In-Reply-To: <000501c1f245$6a304ca0$1aefffcc@Shadow> > > You really have me going about the 9 track behavior tho > null portion of tape as record delimiters "crap in the gap" > problems of the past, and other such things. > > So far what ive learned about those things is nothing as > many years around this stuff conditioned me to expect. > > If i spool the whole raw tape using a driver that knows > nothing of any null gaps and simply spool all bytes that > are bytes to a file .... could not i then pull the desired content > out of the spool if i knew the format of the data ? > > If random access is what they are doing, how did they deal > with a rewritten record, pad the unused portion of the record > to overwrite trailing garbage ? or was the bytecount in a rewritten > headder so that the controller knew the valid byte count ? By its physical nature, a magtape is a sequential-access device. One can of course keep track of position on the tape and use it as a "random-access" input device. Standard magtapes as block-replaceable devices were not at all common, and were really sort of a stunt, "see what I can do" phenomenon. > a tape with blank as delimiter/filler and records with no or > painfully terse descriptors seems to me very .... um something. That's the way it is when hardware is not very clever. Back in the olden days. However, the record mark delimiter was more sophisticated than just blank tape. It was actually a pair of characters surrounded by blank tape, a two-character record, that could be detected by analog circuitry. carl

23 years, 11 months

Tape dumping programs for Unix/Linux...

by cdl＠proxima.ucsd.edu

> From: Raymond Moyers <rmoyers(a)nop.org> > To: classiccmp(a)classiccmp.org > Subject: Re: Tape dumping programs for Unix/Linux... > Date: Thu, 2 May 2002 16:37:30 -0500 > In-Reply-To: <200205021718.g42HI9X7086853(a)daemonweed.reanimators.org> > > On Thursday 02 May 2002 12:18, you wrote: > > > > Whats wrong with cat ? > > > > What's wrong with cat (and dd, and arguably the whole Un*x concept of > > files-as-bytestreams for that matter) is that it loses information. A > > magnetic tape is not an ordered stream of bytes, it is an ordered > > stream of files of records, and each record has a length. > > Here you are talking about a data tape with fields that make up records > where the records are all the same size and the fields being varaible > length inside the record but repeating in all the other records. > > But a tape like this, from the days when tapes was used as random > access devices is not the format of a system archive tape is it ? > > > So you are forced to result to multiple disk files to maintain the file > > structure. > > (which adds to your hassle because now you need to manage collections > > of files instead of a single tape), > > Like with a tarball ? > > > and as you are copying the files to bytestreams you lose the record > > length information. > > Unless you are going to resurrect some old general ledger program > why is this important ? For the same reason it is important to resurrect old computer hardware. I thought that would be obvious to people who read this mailing list. carl -- carl lowenstein marine physical lab u.c. san diego clowenstein(a)ucsd.edu

23 years, 11 months

dd for err recovery

by rmoyers＠nop.org

cat /dev/floppy > /test1 cat: /dev/floppy: Input/output error -rw-r--r-- 1 root root 18432 May 3 02:09 test1 Bad floppy right ? So time for dd, noerror tells it not to quit sync tells it not to aggregate a short read with the good ones, but to fill the remainder of the short read with zeros so ... dd conv=sync,noerror if=/dev/floppy of=/test2 ( bs=defaults to 512) -rw-r--r-- 1 root root 1474560 May 3 02:18 test2 and we have the whole image of the proper size but including bad sectors filled in with zeros Raymond

23 years, 11 months

Tape dumping programs for Unix/Linux...

by cdl＠proxima.ucsd.edu

> From: Raymond Moyers <rmoyers(a)nop.org> > To: classiccmp(a)classiccmp.org > Subject: Re: Tape dumping programs for Unix/Linux... > Date: Thu, 2 May 2002 14:08:41 -0500 > In-Reply-To: <20020502200530.E35218(a)MissSophie.unixag-kl.fh-kl.de> > > On Thursday 02 May 2002 13:05, you wrote: > > On 2002.05.02 18:25 Raymond Moyers wrote: > > > Whats wrong with cat ? > > [...] > > > I see most are using dd when cat is all they need > > cat(1) and dd(1) do not read / recognize the _physical_ block size of > > the tape. > > At the portion of the work where you just want to get the stuff > spooled to a file, you dont care about "block size" yet, you > just need to get it pulled off. > > Unix will treat any device as a stream of bytes > > On my old sony, mkboot is broken, you cant use the OS to > create a bootable volume of itself > > so ... you hang the old scsi disk off your linux box and > cat /dev/sdb > /files/sonyhdimage.img > > hang the new scsi disk off your linux box > > cat files/sonyhdimage.img > /dev/sdb > > Put new disk in sony, look mom it boots !! > > Now you redo the disklabel and shove everything > except root up to a new volume above the footprint of the old disk > redo the middle volumes to suit ... move the stuff back down > mount the new space as /usr/local whatever > > Now you have a 1g bootable disk in a machine that cannot create > one for itself... > > Do you see what im getting at here ? hello ? > > and guess what ... i never even bother to involve myself with > any "block sizes" even as the multiple volumes on > that image uses a mix of logical block sizes. Guess what. You aren't dealing with structured magtapes. And it's a very rare disk drive that has a mixture of block sizes. carl -- carl lowenstein marine physical lab u.c. san diego clowenstein(a)ucsd.edu

23 years, 11 months

Tape dumping programs for Unix/Linux...

by cdl＠proxima.ucsd.edu

> From: Raymond Moyers <rmoyers(a)nop.org> > To: classiccmp(a)classiccmp.org > Subject: Re: Tape dumping programs for Unix/Linux... > Date: Thu, 2 May 2002 11:25:19 -0500 > In-Reply-To: <5.0.0.25.0.20020502090947.02f88e30@pc> > > > > At 02:01 AM 5/2/2002 -0700, Ethan Dicks wrote: > >I can use dd to slurp > >stuff off of tape, but it's tedious. What tools are people using for > >tape archiving under Linux or Solaris? AIX seems to come with "tcopy" > >that essentially pulls everything off the tape until logical or physical > >EOT. I'm looking for something similar - point it at the drive and > >siphon it on down. > > Whats wrong with cat ? > > use the /dev/nst0 device, its the one that dont rewind > ( use mt commands for that kind of stuff ) > > cat /dev/nst0 > file1.tap > cat /dev/nst0 > file2.tap > > and so on You have just thrown away all of the data structure on the tape. No more clues about block lengths, file marks, etc. Some original software is going to need that information to work properly with whatever else is on the tape. carl -- carl lowenstein marine physical lab u.c. san diego clowenstein(a)ucsd.edu

23 years, 11 months

Tape dumping programs for Unix/Linux...

by cdl＠proxima.ucsd.edu

> Date: Thu, 2 May 2002 06:25:24 -0700 (PDT) > From: Ethan Dicks <erd_6502(a)yahoo.com> > Subject: Re: Tape dumping programs for Unix/Linux... > To: classiccmp(a)classiccmp.org > In-Reply-To: <Pine.LNX.4.44.0205021957030.15892-100000(a)floodland.tved.net.au> > Sender: owner-classiccmp(a)classiccmp.org > Reply-To: classiccmp(a)classiccmp.org > > > --- cvisors(a)carnagevisors.net wrote: > > there is also dump & restore, if the Sparc is running solaris there is > > ufsdump and ufsrestore, and finally if all else fails tar > > these programs should allready be (dump and restore) on the redhat box. > > You misunderstand the direction I'm going. I have magtape with data > already on it. I want to extract that data into a file or set of > files on the disk that I can then burn to CD-R. I can use dd to move > raw records, but I would like to also know what the block size was > for a particular file so I could reconsitute the tape later if > necessary. I'm not so worried about the VMS BACKUP tapes I need to > spin off - I want one saveset per file. If I want to dup any install > tapes (non-VAX), the blocking becomes more critical. > > Essentially, a physical backup that is primarily for data recovery, > but secondarily for later restoration. Yes, that is what "copytape" was written for. Works quite well, especially now that disks are (again) much larger than tapes. The balance keeps shifting back and forth over the decades. carl -- carl lowenstein marine physical lab u.c. san diego clowenstein(a)ucsd.edu

23 years, 11 months

Tape dumping programs for Unix/Linux...

by cdl＠proxima.ucsd.edu

> Date: Thu, 2 May 2002 05:34:09 -0500 (CDT) > From: Doc <doc(a)mdrconsult.com> > To: classiccmp(a)classiccmp.org > Subject: Re: Tape dumping programs for Unix/Linux... > In-Reply-To: <Pine.LNX.4.44.0205021957030.15892-100000(a)floodland.tved.net.au> > > On Thu, 2 May 2002 cvisors(a)carnagevisors.net wrote: > > > there is also dump & restore, if the Sparc is running solaris there is > > ufsdump and ufsrestore, and finally if all else fails tar > > these programs should allready be (dump and restore) on the redhat box. > > I'd be very interested to know if RedHat dump/restore will fly on > those magtapes. Linux' version only works on ext2 filesystems on the > dump side, but since the tape archive (_IF_ it was generated by unix > dump) isn't exactly a filesystem.... My bet would be a big no go, but > now I'm curious. > BTW, Jochen turned me on to the maketape utility from PUPS a while > back. It works very well. By their nature, dump and restore (or ufsdump and ufsrestore) are operating-system specific. Dump in particular works on the raw disk image and must have intimate knowledge of the way the operating system constructs a file system. On the other hand, I was once successful at restoring a dump tape made on a MicroVax Ultrix system using "restore.old" on a NeXT. I was rather astonished that it worked. carl -- carl lowenstein marine physical lab u.c. san diego clowenstein(a)ucsd.edu

23 years, 11 months

APPLEVISION Monitor

by acme_ent＠bellsouth.net

> From: Richard Erlacher <edick(a)idcomm.com> > What's always annoyed me with "brand-name" PC's is that the packaging ALWAYS > deviates from the "norm" established by the DIY market. Consquently, your > DELL, Gateway, or Compaq was never upgradable, because the CPU or hard disk > wasn't supported by the BIOS, or some peripheral wouldn't fit in the system > because of address conflicts. Simple things like the on-board video caused > problems when they failed because one couldn't disable them, or, if one did, > the now-broken native video interfered with the replacement. Even printer > ports posed such problems. Many times the packaging itself was the problem. > Have you ever tried to replace or upgrade the CDROM drive in an HP PC? Actually I've found that CD-ROM drives are among the easiest components to replace in HPs. Often the floppy disk drives and power supplies have a weird form factor, and when it comes to motherboards, forget it. I have found HP and Compaq units where, in order to replace the CD-ROM drive (or *any* drive) I had to pull the motherboard, which seems pretty bizarre in itself. Glen 0/0

23 years, 11 months

Googling and "egg-sucking" (was Re: "Toy" computers...)

by cdl＠proxima.ucsd.edu

> Date: Wed, 1 May 2002 19:52:05 -0500 (CDT) > From: Doc <doc(a)mdrconsult.com> > To: classiccmp(a)classiccmp.org > Subject: Re: Googling and "egg-sucking" (was Re: "Toy" computers...) > In-Reply-To: <3CD004D7.3282.A8CC01B@localhost> > > On Wed, 1 May 2002, Stan Sieler wrote: > > and, re: > > > Hey, guys. Simplify. A Google search on the phrase "suck eggs" leads > > > to a clear explanation of the historical use of the phrase, dating > > > back to the 16th century in English, and older in other languages. > > > > > > < http://www.quinion.com/words/qa/qa-tea1.htm > > > > > Nice try, but it doesn't address what I think most people are interested > > in learning about (for that phrase, anyway :) ... sucking eggs. > > It address, instead, the concept of teaching people something they > > already know. > > Well, I dunno what most people are interested in learning about, but I > know that referral to "teaching people something they already know" was > the point of my original use of the phrase. I thought people on this list were interested in historical stuff. An investigation into the antiquity of the expression seemed appropriate. On the same Web page one finds a much more antique version of the same idea in Latin, which can be translated as "Don't teach a fish to swim". carl -- carl lowenstein marine physical lab u.c. san diego clowenstein(a)ucsd.edu

23 years, 11 months

Tape dumping programs for Unix/Linux...

by dquebbeman＠acm.org

> > The emulator community is vigorously using a tape image container > > format known as TAP for precisely this purpose. ... > Darn...sounds like a subset of what I use. I'd be interested > in knowing more about TAP (with an eye towards adopting use of it), > and would suggest some possibly missing features might be: > > - ability to flag if the current tape record had a recovered read > error (obviously, not all hardware/OS's support getting that information) No. And I see no useful purpose in including that in the format. If the read was recovered, you have the data; surely you would *not* want to recreate a tape and make a previously marginal block, marginal again on a clone? > - ability to flag if a particular tape record had a hard error > while reading it No (I can say this even though I'm about to ask): do you mean an unrecoverable error, or one that was corrected by the hardware (as opposed to being corrected by software)? Either way, if the error was corrected, see my response above. > - ability to flag if an End-of-tape marker/indicator was seen > while reading the the current record (again, not all > hardware/OS's support getting that information) No, and again, I can't see how this data would be used to recreate the tape or would be needed by an emulator. It's kind of like asking if a particular hardware emulator also emulates memory parity errors so that you can see memory parity errors in the logs. Why?? > - overall header at start of file, recording information about the tape No, although I did consider suggesting some extensions like this. One problem I have encountered with some old CDC tape formats dealt with how blocking got handled. But my current feeling on this is that if its blocked on taped, then the records will come off the taoe with their proper lengths (I encountered this not trying to read a tape, but trying to create an image of a tape that no longer exists by a desctiption of its contents). Anyway, I encode that kins of descriptive information (what kind of computer, encoding, #tracks, etc) in the filename, or in the name of the directory containing the file, or in a README. > I have a program called "tapedisk", which reads an arbitrary tape > and "copies" it to a single disk file (or set of files, if the size of the > output file exceeds the maximum disk file size). The purpose of > tapedisk is to allow a future exact copy of the tape to be recreated > on another tape (of equal or larger size). (That future copy would be > made with the companion program, disktape.) Additionally, most of > my other tape-reading utilities know how to read a tapedisk format > disk file as though it were a tape. This sounds familiar... is it on the web somewhere? > This is what I store on a per-tape-record basis: ... So you really do want to recreate bad tapes as bad tapes... Why? > This is some what I store as a "header" at the start of the > overall output: ... Yeah, this info is README fodder... why on earth program that? > As you can see...a lot of info, but all necessary to faithfully > reproduce the tape later and/or to understand *why* the file might > (or can't) be used to completely reproduce the tape. Uh, again, can't understand why you'd need to recreate bad tapes. As to the understanding, README.DOC... etc... > This is part of a product we sell on MPE/iX systems, but I'd be happy > to document the structures and/or work with other people on standards > in this area. > > There's room for potential improvement. For example, is it worthwhile > to have a table at the front of the output file that specifies where > the first N EOFs are? You just used that nasty, bad word "standard"... TAP is a convention, not a standard. ;) However, I'm not King of this Kingdom, we're a collective (right out of Monty Python's Search for the Holy Grail). You might try hooking up with the emulator community and ask your questions there. Regards, -doug q

23 years, 11 months

Anyone need 2112 RAMs?

by acme_ent＠bellsouth.net

> From: Lawrence LeMay <lemay(a)cs.umn.edu> > I could use some 2114's and C2109-4's. These are used in Teraks for Video > memory and System memory. Just in case anyone knows of a source ;) Jameco sells the 2114N for $1.49. Glen 0/0

23 years, 11 months

MP/M was CP/M-86

by acme_ent＠bellsouth.net

> From: Freek Heite <f.heite(a)hccnet.nl> > On what kind of hardware is this MPM (86?) running? Newbies that want to > experiment with MPM, would most likely want an implementation of MPM for > the IBM PC hardware - but is that available somewhere? The downloads that > were mentioned a week ago (mpm8621i.zip etc.) are for some compupro hardware. Actually, I'd like to get MP/M for my Zenith Z-100s. Anybody know if this is available?? Glen 0/0

23 years, 11 months

Tape dumping programs for Unix/Linux...

by dquebbeman＠acm.org

> At 04:10 PM 5/2/2002 -0400, Douglas H. Quebbeman wrote: > >No. And I see no useful purpose in including that in the format. > >If the read was recovered, you have the data; surely you would > >*not* want to recreate a tape and make a previously marginal > >block, marginal again on a clone? > > Choosing between the loss of all the data, and a partial > copy, I'll take the partial copy. > > I have many 8-inch disks with bad blocks. I'd like to preserve > the data if at all possible. A simplistic 'dd'-style read > won't preserve everything; it'll bail out when it has a problem. ??? I just did a 'dd' of a bad QIC-80 tape; it read the entire tape as a single file, and didn't bail out. I've not done that with magtape, but ISTR someone else here saying that 'dd' does raw reads, bad blocks and all... My bad if not true. -dq

23 years, 11 months

Tape dumping programs for Unix/Linux..

by dquebbeman＠acm.org

> However, if I notice recovered-reads (or hard errors) on old 9-track > tapes, I often see fewer recovered reads (or hard errors) if I try > the tape one more time. I assume that going over the heads once > may have knocked off a bit of dust/dirt/something that affected > the tape the first time. Note that I don't discard the > results of the first run until the second run finishes... hey! Me too! > I've had one tape break during a second run :) Ouch! Acetate backing? > > > Go buy a 9-track drive and hang it on your *nix box. > > > Let me send you a 9-track tape. You read it any way > > > you want. You send me the tape back. > > > > > Then you go get a second tape, and put the data back on > > > any way you want. Then send it to me, and I'll tell you > > > if your technique works or not. > > BTW, the only way you can be *SURE* you got all the data on > the tape is if *EVERY* read-request returned fewer characters > than you asked for. E.g., if you did: > bytesread = read(fromfd, buffer, BUFSIZE); > and you get BUFSIZE bytes in, then there's a chance that that > tape record had BUFSIZE + 100 bytes ... and you've just lost > those last 100 bytes. I *just* recently discovered this, and will incorporate that into a utility I'll be hosting on the Prime. -dq

23 years, 11 months

S/36 OS?

by xds_sigma7＠hotmail.com

SSP... Why, do you need a copy or something? I have it on 8" floppies... SSP stands for System Support Program, FYI. Will J _________________________________________________________________ Join the world’s largest e-mail service with MSN Hotmail. http://www.hotmail.com

23 years, 11 months

New Finds for the Museum

by jrkeys＠concentric.net

This week has been a little slow and have to watch the cashflow. 1. 30 plus cartridges for the Intellivision (free) 2. hp 82901M Flexible Disc Drive excellent shape ($1.99) 3. IBM 3.5 FD external type 4865 ($1.99) 4. PowerBook 150 with adapter and case (Targus) ($20) 5. NCD ExploraPro x-terminal ($1) 6. Sun SPARCStation IPC ($1) 7. Two AppleCD 600e ($1ea) 8. Four AppleCD 300 ($1ea) 9. MicroScribe model 450/2013 ($1) 10.WYSE model WY-150-03-01 ($6) 11. TOMY robot ($1) 12. digital VT420-C2 (free) 13. AMT FormsWriter-242 (free) 14. AMIGA 500 (free) 15. digital VT240 model VS240-B ($8) That's it for this week the balance is too new to post.

23 years, 11 months

Tape dumping programs for Unix/Linux..

by dquebbeman＠acm.org

> Fair enough, but remember my post was about cat vs dd, and > was not dealing with all these other issues being tossed > up, it was to point out that what he was doing would be easier > with a simpler tool > > It certainly didnt apply to preserving the information > needed to rewrite a new 9 track tape. > > I think your being a bit rough on me here, your givin me > a GI bath for things that was outside of the scope of my > focus. Ok, and fair enough... several of us detected that you might not quite grasp the scope of the issue, yet your dogged assertiveness was sending a different message. I apologize for any part of my remarks that came off like an attack. Regards, -doug q

23 years, 11 months

Tektronix 4052A GPIB Programming Guide Item # 1727379522

by rigdonj＠cfl.rr.com

<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1727379522>

23 years, 11 months

Tektronix 4050 Series Basic Reference Guide HURRY!

by rigdonj＠cfl.rr.com

<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1726561113> It closes in 54 minutes!

23 years, 11 months

Tape dumping programs for Unix/Linux...

by Lee.Davison＠merlincommunications.com

Engineers are great- they're like laser beams. They are intense and highly focusable. .. and they bounce around the room until you don't know which direction they're comming from. Lee. ---------------------------------------------------------------------------- ---- This email is intended only for the above named addressee(s). The information contained in this email may contain information which is confidential. The views expressed in this email are personal to the sender and do not in any way reflect the views of the company. If you have received this email and you are not a named addressee please delete it from your system and contact Merlin Communications International IT Department on +44 20 7344 5888. ________________________________________________________________________ This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________

23 years, 11 months

Tape dumping programs for Unix/Linux...

by dquebbeman＠acm.org

> Keep in mind one thing: engineers who spend their lives working on tape > hardware thought it was important enough to be able to signal recovered > errors ... for a reason. Engineers are great- they're like laser beams. They are intense and highly focusable. But they don't illuminate a wide area when focused. OTOH, take the lowly, dim incandescent lightbulb. Not intense. Not very focused. But it lights up the whole room. Ok, now that everyone's got me pegged as the dim bulb in this group... (didn't think I was going to leave that one for someone else, did you?), let me finish my thought... Anyway, my point is that sometimes engineers are so focused that they don't see the big picture. But I'm not disagreeing about the need to know about read errors (or write errors for that reason). Regards, -dq

23 years, 11 months

Tape dumping programs for Unix/Linux...

by dquebbeman＠acm.org

Stan sayeth: > > No. And I see no useful purpose in including that in the format. > > If the read was recovered, you have the data; surely you would > > *not* want to recreate a tape and make a previously marginal > > block, marginal again on a clone? > > > NOOOO! It's *IMPORTANT* to know if there was a question about the > accuracy of the data! That's *WHY* some tape drives even *tell* > you there was a recovered error ... so the user could use that > information! I do that during the first dozen-or-so reads of the tape... > It's like getting a recovered parity error on memory. > Should you know about it? DAMN STRAIGHT YOU SHOULD! heh... for years, any IBM compatible PC would, on detection of a parity error, deliberately crash. Doesn't matter why, I just lots my stuff... > Without recording that information, you also can't answer > important questions like: is the orginal tape in good shape? Sure, *make note of it*, but I don't necessarily view the image file as the only correct place to put that info. But it's not a bad idea, just a bit Brobdignagian... If I was Tim Shoppa and was doing analog reads of tapes so far gone that you've got only one try to get it right, sure. But like I said before, traditional methods shouldn't be used on these tapes. > > > - ability to flag if a particular tape record had a hard error > > > while reading it > > > > No (I can say this even though I'm about to ask): do you mean an > > unrecoverable error, or one that was corrected by the hardware > > (as opposed to being corrected by software)? Either way, if the > > error was corrected, see my response above. > > If it was corrected, then there was no error (other than a > recovered read, already correct recorded via the earlier bit :) > > I meant a real, live, actual error. (E.g., missing oxide) > > When recording the contents of a tape it's **IMPORTANT** to know > that there was an error there. If you simply skip the erorr and > keep reading, you've lost data. > Did you lose original user data? Possibly, and you've definitely > lost data about the tape (i.e., the fact there was an error). > > By recording the fact an error occurred, along with any data > your tape drive/OS *may* have sent you, you preserve the ability > to act wisely in the future. For example, by recording the > fact there was an error at megabyte 100 in a 102 MB file, > the user would have confidence that when that file is eventually > extracted, the first 99 MB of it is in fine shape. Y'all must encounter a lot more marginal tapes than I do. The ones I can't read have gone all the way down to where they will require an analog read. If I can read it digital at all, I'll reread the dang tape until I get ever record error-free. The wet read is most useful in this application. > > > - ability to flag if an End-of-tape marker/indicator was seen > > > while reading the the current record (again, not all > > > hardware/OS's support getting that information) > > > > No, and again, I can't see how this data would be used to recreate > > the tape or would be needed by an emulator. It's kind of like asking > > if a particular hardware emulator also emulates memory parity errors > > so that you can see memory parity errors in the logs. Why?? > > With 9-track tapes, software writing to the tapes generally watches > for an indication that the end-of-tape marker (a short silver > reflective strip) has been seen. At that time, it can prepare > to do a reel-switch. Although some people feel they can backspace > and write reel-switch info prior to the EOT marker on a 9-track > tape, that's technically not safe (and opens up the possibility > of getting what's called (in 1979) "crap in the gap"). Anyway, > the ANSI (?) standard for 9 track tapes specifies a minimum length > of tape be available for writing after the EOT marker ... a length > that should be sufficient (even with modest multiple outstanding > write-ahead requests) to write the reel switch information. I think you're missing my point- I don't believe there are any 9-track drives that split physical records across reels of tape. If I'm wrong, please correct me. > On at least one OS, Burroughs MCP, one could detect that EOT at > read time. Then, if one is doing multiple read-ahead requests, > one can moderate them appropriately. Yes, yes, yes, of course the EOT is detected while reading. But it happens *between* records, not *inside* them. > Ok...the short answer: it's information. You don't throw away > information without a darn good reason. :) Hey, if physical records *can* be split bwteen reels, then you are absolutely right. > > > - overall header at start of file, recording information about the tape > > > > No, although I did consider suggesting some extensions like this. > > One problem I have encountered with some old CDC tape formats > > Sorry...if you want a professional program, not something like > that toy cptape, you *WILL* have this information. > > Been there, worked on that, for over 30 years. Trust me...you > *want* all the information you can get. Actually, all I want is that the system software and applications can use the data from the tape without detecting its coming from some place other than a physical tape. So far that goal has not required the extreme mesaures discussed here. > > Anyway, I encode that kins of descriptive information (what kind > > of computer, encoding, #tracks, etc) in the filename, or in the > > name of the directory containing the file, or in a README. > > If two items of data are separated, what happens to them? > Yep. Should be 'nuff said :) Well, Raymond and I agree that tarballs work well for this, as well as other such methods of encapsulation. > > > I have a program called "tapedisk", which reads an arbitrary tape > > > > This sounds familiar... is it on the web somewhere? > > The MPE V version was/is (can't recall which), and was free. > The MPE/iX version is a product from our company. I was thinking of some Linux thing... I've only a few hours of HP3000 experience. Looked like a nice extension of the 2000 Access system, at first... > > So you really do want to recreate bad tapes as bad tapes... > > > > Why? > > No...I want to know that a problem existed, and where that > problem was. > > Again...this is basic, vital, and indisputable. You *NEED* to > know if there was a problem with the tape, and if you're trying to > extract a particular file you need to know where any problems > are in that file. Otherwise, you'll be lying to the user. > > If you know where within a file an error was found, then you've > got a chance at recovering most of the rest of the data successfully. > If you know an error occurred *somewhere* in a file, but not > where, then you have a large pile of bits which *might* be trash, > and *might* be useful ... but neither you or the user knows. > And, if you don't know where the errors were (and how many there > were), you can't reliably restore the data. That data might > be banking information that your company is being audited on; > it might be data that could clear someone of a crime...you simply > don't know. > > Data is important...that's why we call it data and not junk :) We're not disagreeing about this, we just have a different time-and-place attitude about it. > > This is some what I store as a "header" at the start of the > > > overall output: > > > > ... > > > > Yeah, this info is README fodder... why on earth program that? > > Uh, 'cuz someone had to do it and build a reliable, thorough > program? I'm not arguing that it's of no value, but I'm looking at cost of effort expended vs. return on investment. I used to always believe in building for the worst-case, but these days it's rarely feasible. The people writing the checks don't want to pay for features they don't think they'll use. > > > As you can see...a lot of info, but all necessary to faithfully > > > reproduce the tape later and/or to understand *why* the file might > > > (or can't) be used to completely reproduce the tape. > > > > Uh, again, can't understand why you'd need to recreate bad tapes. > > Again...you're *NOT RECREATING BAD TAPES*. I understand. Recreating tapes from images is not a criterium. > > You might try hooking up with the emulator community and > > ask your questions there. > > This being ClassicCmp, I thought they might be here, too :) One or two of us, at least! > Besides, this isn't an emulator question so much as a data > preservation question. Related issues, to be sure, but not necessarily identical ones. I don't think we're really disagreeing here; you circle the block to the left, I circle to the right. We both make it to where we want to go. Regards, -dq

23 years, 11 months

Mainframe emulation and serial comms (was Re: "Toy computers)

by dquebbeman＠acm.org

> > There are/were apparently a number of Apple LocalTalk cards made > > for PC usage. One of them is the PC MacBridge by Tangent Technologies - > > now defunct - which is a short 8-bit card based on the Zilog Z8530APC > > chip. A google search will disclose multiple others also. > > I have a native Apple LocalTalk ISA card manufactured by Apple. It does an > excellent job and the PC communicates seamlessly with the Macs in the > apartment. Since the thrust of this topic is find a board that can be used to do IBM BISYNC communication, would you happen to know what chipset is used by the board? It would be hard to use it if no one knows how to write software for it... -dq

23 years, 11 months

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