test-drb March 2000

test-drb@ccmp.vtda.org

150 participants
515 discussions

by pete＠dunnington.u-net.com

On Mar 29, 13:41, Bill Pechter wrote: > > In article <00ce01bf990a$26953aa0$03e893c3@proteus>, Peter Pachla > > <peter.pachla(a)wintermute.org.uk> writes > > I have an external tape drive which I am told came from a Prime of some > > sort which you can have. I don't know what sort of tape it takes as I > > didn't get any with it. Perhaps someone else on the list could say > > whether it is any use to you. It has no external markings except for a > > sticker showing that it passed statutory testing in 1988. The drive > > itself is an Exabyte Model EXB 8200, does anyone recognise this? > It's an 8mm 112M Exabyte... www.exabyte.com. Works great with any > SCSI single ended (usually) interface. I have two here, one sold originally as a PDP-11/83 add-on, and one from a Pr1me. I upgraded the firmware in the older one using code from www.exabyte.com, and both work very nicely on my Unix machines and an Acorn Archimedes. They don't do compression and the standard 8200 doesn't have the high-speed search that the 8200S has, but they handle a reasonable data rate and hold around 2.2GB per tape. Lots of people use 8mm video tape; I prefer to use proper data cartridges, though. -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 1 month

Swap Meet

by steverob＠hotoffice.com

Went the the Hamfest at the Motorola Factory in Plantation (western Ft. Lauderdale) last weekend. From what I understand, it used to be a regular event but, now it's held infrequently. There were quite a few sellers there but, not too much computer stuff. I found a micro-based controller for $10. Looks like it was used for some kinda automated inspection or manufacturing system. The system consisted of 4 large wire-wrapped boards and 4 fairly large power supplies. There was some damage to the innards so, I bought it strictly for the parts. Got a ton of TTL devices and other goodies out of it. Also found a "NIDA" Counter / Timer. It's an educational tool used to teach digital logic. It's in great condition considering it came from the school board. In my experience, most of the stuff from the schools is pretty beat up. Anyway, it's very cool and only cost me $5. I had other comittments so only stayed until 8:00 AM. At that time, sellers and buyers were still filing in. Probably missed some good stuff but, oh well... Later, Steve Robertson <steverob(a)hotoffice.com> > > We stayed at the meet for about an hour or so, and decided > that we had had > enough of the wall to wall people. I had fun but I doubt that > I'll go again, > unless I learn more about ham radio stuff. I'll hold out for a vintage > computer fest instead. > > Ernest

24 years, 1 month

PDP11/23 More dumb questions

by pete＠dunnington.u-net.com

On Mar 28, 15:25, CLASSICCMP(a)trailing-edge.com wrote: > >> >M7195 > >> > >> 128 kbyte RAM > > >It's actually a MXV11-B Multifunction card, with 128KB RAM, and ... > > >> It's also particularly confusing, because you evidently have no serial > >> line cards nor disk controllers in the backplane. I have no idea > >> how you even got the ODT prompt out of the machine. > > >... the MXV11-B has two SLUs, of the same type as a DLV11. > > Yeah, that makes more sense. I still don't know how his machine is > supposed to boot from disk without a disk controller, though! Ah, that's the magic part :-) -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 1 month

Parallel port hard drives?

by pete＠dunnington.u-net.com

On Mar 28, 19:14, Tony Duell wrote: > The other thing is that when 96 tpi drives were in common use, some (lesser) > manufactuerers fitted the narrow head to all drives (even 48 tpi ones!). > Or at least some system builders/OEMs did. I have heard rumours that a > well-known BBC micro supplier sold 40 track, 80 track, and 40/80 > switchable drives. They were actually all the same (80 track, 96 tpi) > mechanisms. The '40 track' ones had been modified to double-step, and the > switchable ones had this mod controlled by the switch. Canon mechanisms, by any chance? or Chinon? > Needless to say, these '40 track' drives can correctly read '40 track' > disks that have been overwritten by 96 tpi drives (since the head in such > a drive only 'sees' the narrower 96-tpi-like track anyway), but what they > can't do is overwrite disks formatted or written on real 48 tpi drives. > Don't ask how I got to sort this out! Yuk! I can imagine :-) > The other question, of course, is how reliable do you need it to be. > > For example, the last time I wrote a 40 track disk in an 80 track (96 > tpi) drive was when I wrote a TRS-80 Model 4 boot disk on this linux box > (which has a 1.2Mbyte 96 tpi drive). I did the following : yes, i do things like that quite often. But not for anything I want to keep (not the one written in the 80-track drive, anyway) because you never know if the drive you use next year will be the same... -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 1 month

Altos machines

by Innfogra＠aol.com

Altos machines came in several generations. 1st Generation Altos 5-ZZ where ZZ was the size of the HD. These were Z80 machines with 5 1/4 inch drives. These are small rectangular desktop boxes. Altos 8XXX-ZZ was a large heavy rectangular desktop box with Z80s or 68000 CPUs. These were generally multiuser machines. ZZ again refers to the size of the 8" HD(10=10 Meg, 12=20 Meg, 14=40 Meg HDs). They used a large custom single board computer the size of the case. The drive controller was a separate half card mounted on top of the SBC. The early 8000s had separate cases for the 8" FD & HD. In later models the drives and cards were integrated in the same case. I think the 68000 processor machines were labeled 68XX-ZZ but it has been too long to be sure. I also think the 68000 machines ran an early version of Xenix. You could get them in versions up to 9 users and a supervisor. 2nd Generation Altos 5XX & 6XX class machines. These looked like squashed hexagons, flat on the bottom and top with two angles on each side. These were medium sized desktop cases, usually beige but often came in custom colors. They carried on the two circuit card configuration. Large SBC with secondary drive controller card. Altos 580 was my favorite. Half height floppy and St 225 20 Meg HD with a Z80 and ran 4 terminals under MPM. They would also run CPM. These also came with FH 10 & 15 Meg HDs Altos 586 came with a 40 meg FHHD and the new 8086 processor and was a 6 user machine. These often ran Xenix and were password protected. While I never had one I think the 686 series machines had the 68000 processor and ran Xenix. These were all squashed Hexagonal shaped machines. I think this line went up to 9XX series numbers with greater amounts of users. 3rd Generation Then there were the Brown floor towers, Altos II & III. These were multiple card towers for large amounts of users. These had 80286 and 80386 processors. I believe there were machines that continued the 680xx processor line too. I only had a couple of these. The Altos II terminal is a rebadged Wyse 100 and the Altos III was a Wyse 50. I think the Altos IV was a Wyse 60 but I am not sure at the moment. Paxton

24 years, 1 month

360K in a 1.2M drive (was: Parallel port hard drives?

by pete＠dunnington.u-net.com

On Mar 26, 16:16, Richard Erlacher wrote: > I'm not sure I am the one who should wake up here. I would repeat "It > doesn't matter whether the diskette is a 1.2 MB one or a 360K type" but it > does depend what sort of drive it is. No, Fred is right. There are plenty of drives designed to use single density or double density disks at 96 tpi, and disks cerified for such use, and they work perfectly reliably for 80 tracks, SD or DD. Historically, such drives predate 1.2M (HD) drives. Provided you use SD/DD media in a drive using the correct write current, and providing there isn't any other leftover rubbish for the wider heads in a 48 tpi drive, any reasonably well-aligned 48 tpi will handle those disks just fine. However, no 48 tpi drive I have ever heard of is designed to use HD 1.2M media, and if you try it, it will give trouble sooner or later. All the evidence indicates that the major factor is the magnetic coercivity of the media. > [...] the fact that the heads designed for 48tpi will write a > significantly wider swath on > the diskette than the 96tpi drive can erase. Consequently, and I'll bet > you've had this experience, you can format a bulk erased diskette to 48tpi > with a 96 TPI drive and have it work for a while. > > The more the diskette is written, by the 48tpi drive, the harder it becomes > for the 96tpi drive to erase its writing, Again, no. Providing you're only reading back the part overwritten by the 96 tpi drive, this is not true. It only matters if you both write with 48 tpi, overwrite with 96 tpi, and then try to read back with a 48 tpi drive -- which is not what was being discussed. And it doesn't make any difference whether the 48 tpi drive writes once or one thousand times, the magnetic field strength is the same! > and, of course, the 48TPI drive > will have the most trouble because the signal not erased in the 96tpi drive > is perceived by the 48tpi drive as noise, while the signal written by the > 96tpi is written at a lower level to begin with, since the drive relies on > the higher coercivity of the medium to generate a larger signal amplitude if > that factor is to come into play at all. No, it doesn't rely on the higher coercivity, not when it's writing single or double density. It only does that for High Density. -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 1 month

Swap Meet

by kyrrin＠bluefeathertech.com

At 20:39 12-03-2000 -0800, John Lawson dared me to... > So... where's the detailed Swap Meet Report???? > > We're waiting... >PS: Post to The List if you dare... :) Ok, I dare. ;-) The Puyallup swap this year was quite crowded compared with last year. I managed to sell a bunch of stuff that I didn't think I would, and some stuff that I thought would sell (almost) didn't. For the record, I sold all the Exabyte drives (the 8500's are holding here for checks from the purchasers -- thanks, guys!) and the small UPS I had. I don't think any of the buyers (with three exceptions) were classiccmp'ers, but all business was appreciated. There were equal amounts of joy and irritation with this year's event. On the 'joy' side was, certainly, good sales. Add to that my finding of not one, but TWO Amp 'Butterfly' tools (if you don't know what one is, you'll have trouble appreciating it), plus some spare batteries for the pair of radios I use for SwapComm and a nice mid-80's vintage Amprobe clamp-on AC meter, and I think I did pretty well. On the irritation side. One fellow showed up with a beautiful mil-spec HF receiver. Those of you familiar with the radio side of things will likely recognize the designation of R-2174(P)/URR, a.k.a. the Racal 6790. It was in great shape, came with its manual and power cord, and had a sticker price of $1,275. Those of you who know this receiver will know immediately that this is a bit exorbitant. In prime shape, they're worth about a grand, and that's what I offered the fellow for it (knowing full well that I'd be going into debt for six months to pay it off!). He insisted on waiting until the end of the day. However, at day's end, I came back to find him wrapping it up. Upon asking what was up, he told me (rather brusquely) that someone had paid him $2,000 in CASH for it. Initially, I was stunned. Not only was that over twice what the unit was worth, but it astounded me that ANYone would be (a) walking around with two grand in cash in their pocket, and (b) would use it to buy a mid-80's HF receiver, however nice. I walked away from that one fuming. In retrospect, and after talking to a friend of mine, it is now my firm belief that the owner was lying through his teeth in an effort to cover the fact that no one had been willing to pay his outrageous sticker price. Here's why I think this. 1). He was wrapping the receiver up as if to ship it. If someone was crazy enough to pay $2K for that unit, said buyer would have taken it with them ON THE SPOT. 2). The seller's attitude throughout the day was loud, obnoxious, and forceful on trying to sell things. Too forceful, in fact. He wouldn't dicker beyond a certain point, and he seemed borderline arrogant in every dealing he had with those around him. From what I could tell, he sold very little that day. 3). His body language, as he was wrapping up the receiver, was most definitely NOT that of someone who'd just closed a two-grand sale. It was more along the lines of "I'm taking my ball and going HOME! To blazes with this whole mess!!" Anyway, that's about it. I deposited more back into the bank than I took out to cover my purchases, so I think I did pretty well. Eric Smith came by on Sunday to pick up the DSD-880's I had for him, plus some other goodies, and it was he who bought my last Exabyte drive. Eric, if you're reading this, thanks again and enjoy! Guess I'll just have to do it again next year. Heck, I might rent a table just to get in early. Let's hope that, if someone has a similar receiver next year, they'll be more serious about selling it at a reasonable price. Caveat (burp) Emperor! -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Bruce Lane, Owner and head honcho, Blue Feather Technologies http://www.bluefeathertech.com // E-mail: kyrrin(a)bluefeathertech.com Amateur Radio: WD6EOS since Dec. '77 "Our science can only describe an object, event, or living thing in our own human terms. It cannot, in any way, define any of them..."

24 years, 1 month

Research Machines Link 480Z

by JRichardson＠softwright.co.uk

>> IIRC at least one of the RML winchester systems was a box about the size >> of a 380Z with a PSU, ST506-interfaced drive and a SASI-ST506 interface >> card. I assume the 380Z interface was a SASI host adapter or something. that sounds like what I maybe have.... never seen a 380Z so I don't know. I've got five or six 480Z machines though, three or four of them with network interfaces, and then two big black metal cabinets - one houses the hard drive, and from memory the other contains either controller logic or floppy drives (these things have been sitting in sotrage for the last 4 years, so it's been a while since I've seen them!) pretty nifty stuff though, I must dig them all out again some day... (they were given to me along with my Diamond wordprocessor, which was the main find, so I only ever powered up the 480's to check that they could talk to the disk unit before they got stored...) someday I will have the time and space to fire these things up again and have a serious play around with them... cheers Jules >

24 years, 1 month

remove

by thomas.h.lindberg＠se.abb.com

remove

24 years, 1 month

PDP11/23 More dumb questions

by pete＠dunnington.u-net.com

On Mar 28, 11:51, CLASSICCMP(a)trailing-edge.com wrote: > On Mar 28, 20:15, Olminkhof wrote: > >The cards are, from one end: > >M7195 > > 128 kbyte RAM It's actually a MXV11-B Multifunction card, with 128KB RAM, and ... > >M8067 > > Another 128 kbyte RAM Or maybe 256K > It's also particularly confusing, because you evidently have no serial > line cards nor disk controllers in the backplane. I have no idea > how you even got the ODT prompt out of the machine. ... the MXV11-B has two SLUs, of the same type as a DLV11. It also has a bootstrap (usually) which is vaguely similar to some of the 11/23+ ad early 11/73 bootstraps, and an LTC. And a million jumper posts. I have a document listing their names/functions somewhere online, if you need it. > There seem to be some (slight) behavioural differences depending on which > serial port I plug the terminal into. Well, the one on the left of the card, looking into it from the back, is the console line, if that helps. > I'm unclear about the switches and lights, but I have the run light on, the > DC light on, the fixed disk write protect switch out and it's red light out, > and the fixed disk ready switch out with it's green light on. Well, that should be running. As Tim noted, there isn't a disk controller in your list, though. I'd expect an RQDX1 or maybe RQDX2 in that machine -- more likely an RQDX1 if the drive is an RD50. If there isn't, it won't do much. It might be worth trying to connect a terminal to the console SLU and seein what happens when you start it. You can break into the bootstrap routine using ctrl-C if necessary. -- Pete Peter Turnbull Dept. of Computer Science University of York

24 years, 1 month

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test-drb March 2000