RE: RK06 alignment pack
[Writing alignment disks] I have an idea that some of these units used an optical interferometer to determine the head position Quite possible. But it also requires the movement control being different from a standard drive, in order to drive at the precision, as well as the feedback from the inferometer. It was probably still a voice coil mechanism, but with very differnet drive electronics. While the servo surface can't be re-written in the field (that is what determines head positions, after all), I see no reason why the data surfaces can't be reformatted on a drive which has a separate servo surface like the RK06/07 Oh, agree. As long as the servo track is ok, the rest is easy. I was specifically referring to the servo tracks. (Which on something like the RL drives is embedded with the data.) The RK06/07 do not have embedded servo. There are 2 disks, 4 surfaces in the pack. One is a dedicated servo surface. That cannot be rewritten in the field, AFAIK the data surfaces can be reformatted. Incidentally, I once saw a procedure (maybe HP) for rewriting the servo surface of a fixed/removeable drive in the field. It used special electronics, but not any special mechanics. It went like this : [...] Well, a drive like the RK05 can also be reformatted in the field. So it all depends on the drive... Sure. The low-track-density drives like the RK05 (HP7900, IBM whatever) don't have a servo signal on the disk. They have an optical position transducer on the positioner for head position feedback. So they can get the heads into position on a totally blank disk. And thus can reformat such a disk. No the procedure I was thinking of was to re-write the dedicated servo surface on the fixed disk stack of a fixed/removeable drive that used a servo signal from the disk. I am pretty sure it was an HP drive, maybe the 7905 or 7906 (I don't have either). -tony
Re: using new technology on old machines. Was: PDP-12 Restoration at the RICM
(I would change the subject line, but I am not sure how to do it in my ISP's web mail client) As far as I know XH558 will be permanently stationed at Finningley after this year's flying season is completed. The full details are here: http://www.vulcantothesky.org/, including dates of flypasts and displays. Regards Rob On 17 June 2015 at 12:16, Christian Gauger-Cosgrove captainkirk...@gmail.com wrote: On 17 June 2015 at 05:09, Huw Davies huw.dav...@kerberos.davies.net.au wrote: Funny I was discussing just this pair of planes last night - I last saw them fly in 1971 at RAF Shawbury. Of course they were both in active service then and I remember watching the Lightning do a supersonic pass with much joy. Off topic for a moment but, do you know perchance what's going to happen to XH558 at the end of this year? I've never had a chance to see a flying Vulcan, and it's too bad I won't ever get to see one (nor did I get to see the awesome display of both of he flight worthy Lancasters flying together last year...). Getting a little closer to the topic at hand, eventually parts will no longer be available for older computers so the decision will have to be made to either retire them or use more modern components to keep them going. Somewhat ironically the ones that can be maintained in ‘original' condition for longer may be the mechanical ones where replacement parts could be fabricated whereas valves and SSI TTL may not be able to be economically produced. The point you raise is comparable to the fact that we'vve basically flown the life out of the last Avro Vulcan, meanwhile here in my home town we're still managing to keep an Avro Lancaster flying after all these years. Also, I realize anyone can infer where I live based on the statements in this e-mail, hah. Cheers, Christian -- Christian M. Gauger-Cosgrove STCKON08DS0 Contact information available upon request.
Re: RK06 alignment pack
On Jun 17, 2015, at 1:50 PM, Johnny Billquist b...@update.uu.se wrote: On 2015-06-17 19:40, tony duell wrote: [Writing alignment disks] As far as I know, in special machines mounted on slabs on stone weighting tons, standing on dampeners, so that you had absolutely vibration free environment, and then a very precisely controlled head control system that could write the tracks at the exact place they I have an idea that some of these units used an optical interferometer to determine the head position Quite possible. But it also requires the movement control being different from a standard drive, in order to drive at the precision, as well as the feedback from the inferometer. Interferometer would make sense, at least for drives of that era. I think modern drives have track spacings small enough that a visible light interferometer may not be sufficient any longer. ... Incidentally, I once saw a procedure (maybe HP) for rewriting the servo surface of a fixed/removeable drive in the field. It used special electronics, but not any special mechanics. It went like this : [...] Well, a drive like the RK05 can also be reformatted in the field. So it all depends on the drive… True, but an RK05 doesn’t have servo data on the platter; positioning is done by reference to an optical widget in the drive. So it depends on mechanical reproducibility being significantly better than the track spacing. Higher density drives use on-pack servo to avoid that constraint. And embedded servo avoids an additional constraint: accurate positioning of one head relative to another. paul
Re: DEC RRD-42 CDROM drives
On Wed, 17 Jun 2015, Jarratt RMA wrote: I have an RRD-42 already, but a spare would be nice if shipping to the UK wasn't too expensive. Any idea how much it would cost? Too much I will wager. Off hand I cannot estimate the size or weight... -- Richard Loken VE6BSV, Unix System Administrator : Anybody can be a father Athabasca University: but you have to earn Athabasca, Alberta Canada : the title of 'daddy' ** richar...@admin.athabascau.ca ** : - Lynn Johnston
Re: Windows and devices - was Re: using new technology on old machines. Was: PDP-12 Restoration at the RICM
On Jun 17, 2015, at 10:50 , Toby Thain t...@telegraphics.com.au wrote: Here's a cute gotcha I hit this week: - Have a running Windows 8.1 machine with PS/2 keyboard. - Shut it down, start up with only USB keyboard. - Shut down and boot again with PS/2 keyboard atached. - Windows ignores it (although BIOS flashes lights normally, etc). - Registry change (found by google) reboot brings it back to life. Can't imagine how many good keyboards were dumpster'd over that one. Working in the GPS industry, I became all too familiar with how Windows can't tell the difference between a Microsoft Serial BallPoint and a 4800 baud NMEA stream. -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: Documation card readers for sale
On Jun 17, 2015, at 16:14 , John Ball ball.of.j...@gmail.com wrote: About six months ago I struck a deal with a place down in California for four Documation M1000's that I've been able to tell so far they all work but I really don't have space for more than one. I've been trying to sell them at a loss for months now over on the Vintage Computer Forums and Nekochan (if you got here you'll find pictures) but no bites. I swear there were people out there that were looking. Where did you folks go? Might anyone here be interested? I absolutely refuse to put them on the curb. Where are they located? I'm known for my poor self-control when it comes to acquiring vintage computer gear, but shipping one of those heavy beasts to southern California might be more than I'd like to spend. :/ -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: Documation card readers for sale
On Wed, Jun 17, 2015 at 7:14 PM, John Ball ball.of.j...@gmail.com wrote: About six months ago I struck a deal with a place down in California for four Documation M1000's that I've been able to tell so far they all work but I really don't have space for more than one. If anyone here does get one, I've got a simple Arduino UNO program that interfaces to the parallel output and sends fully decoded information over USB at quite high speeds. The M-1000-L is a great reader, very reliable, and easy to work on too (I did a little routine maintenance, but mine was in 100% working shape when I got it). Here's a video: https://www.youtube.com/watch?v=N27Mr199I7g I'm also working on getting a cable made to hook up to the M843 CR8-E punched card reader interface for the PDP-8/E, but that's a project for another day (year?). Kyle
Re: RE: using new technology on old machines
On 2015-06-17 13:28, Dave G4UGM wrote: I found it easier to think of it in DC terms. So the Cap charges through R5 + R3 and R9 + R8. As the Cap charges the voltage on the base of Q1 rises until it turns on, which then turns on Q2. While the cap charges, it steals the base current which would otherwise have gone to Q1, thus keeping Q1 turned off. When the cap nears the end of the charge, more current goes to the base of Q1 which turns on, turning on Q2, which raises the voltage over R8 and R9. Since the voltage on a capacitor cannot change instantaneously, the voltage on the base of Q1 rises while the cap discharges through the base of Q1, keeping it hard on. As the cap discharges and charges in the reverse direction, the base current of Q1 decreases and ultimately Q1 turns off, turning off Q2 and lowering the voltage over R8 and R9, and the cycle starts over. For the circuit to work, I think (I may be wrong) the base current supplied to Q1 by R5 and the pot has to be not quite sufficient to turn it on. Also the cap is reverse charged for one half cycle. I believe this is a classical astable multivibrator circuit, but not the more common one with two cross-coupled transistors with capacitors from the collector of one to the base of the other. The DEC circuit I think can be seen a lot in old Siemens application books from the 1960s, such as may be found here (note German books): http://rainers-elektronikpage.de/SIEMENS-Fach---u_-Datenbucher/siemens-fach---u_-datenbucher.html /Jonas At this point the cap is then charged (or discharged) in the reverse direction via Q2, D5 and R4 until Q1 turns off. At first glance I thought R9 might be there to provide some hysteresis in the switching thresholds for the RC charge/discharge but it looks like it acts in the opposite direction to that. The base circuit of Q3 (the first stage of buffering) will draw current from the high-impedance side (R8,R9) of the oscillator output, pulling up the C5,R9 junction when Q2 is off, so it will probably affect the oscillator and be necessary to get the 'proper' functioning of the oscillator portion of the circuit. I included that in my LTSpice model ... but it doesn't actually have that much effect... Dave G4UGM
Re: Documation card readers for sale
Mike where did you get new rubber roller things for the card reader? Thanks for the link on theinterface. Ed# _www.smecc.org_ (http://www.smecc.org) In a message dated 6/17/2015 7:21:15 P.M. US Mountain Standard Time, mloe...@cpumagic.scol.pa.us writes: On Wed, 17 Jun 2015, Kyle Owen wrote: On Wed, Jun 17, 2015 at 7:14 PM, John Ball ball.of.j...@gmail.com wrote: About six months ago I struck a deal with a place down in California for four Documation M1000's that I've been able to tell so far they all work but I really don't have space for more than one. If anyone here does get one, I've got a simple Arduino UNO program that interfaces to the parallel output and sends fully decoded information over USB at quite high speeds. The M-1000-L is a great reader, very reliable, and easy to work on too (I did a little routine maintenance, but mine was in 100% working shape when I got it). Here's a video: https://www.youtube.com/watch?v=N27Mr199I7g There's also Brian Knittel's USB interface for the Documation readers: http://media.ibm1130.org/sim/cardread.zip I built one, and it works well. Mike Loewen mloe...@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/
Re: Documation card readers for sale
On Wed, 17 Jun 2015, Kyle Owen wrote: On Wed, Jun 17, 2015 at 7:14 PM, John Ball ball.of.j...@gmail.com wrote: About six months ago I struck a deal with a place down in California for four Documation M1000's that I've been able to tell so far they all work but I really don't have space for more than one. If anyone here does get one, I've got a simple Arduino UNO program that interfaces to the parallel output and sends fully decoded information over USB at quite high speeds. The M-1000-L is a great reader, very reliable, and easy to work on too (I did a little routine maintenance, but mine was in 100% working shape when I got it). Here's a video: https://www.youtube.com/watch?v=N27Mr199I7g There's also Brian Knittel's USB interface for the Documation readers: http://media.ibm1130.org/sim/cardread.zip I built one, and it works well. Mike Loewen mloe...@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/
Re: Documation card readers for sale
On Jun 17, 2015, at 19:48, Chris Osborn fozzt...@fozztexx.com wrote: On Jun 17, 2015, at 7:43 PM, Mark J. Blair n...@nf6x.net wrote: Are the readers in question these ones in Canada? When you drive up there to get them, you can stop by my house on your way home and drop one off. I’m in Sacramento so I’m right on the way. I’ll let you play some air hockey while you’re here! :-P I sincerely thank you for the offer, but I won't be driving up there. I don't like driving long distances (despite commuting about 20,000 miles per year), and I don't particularly like traveling in general, either. Nope, I'm totally a stay-near-home type, with my one concession being a drive up to San Luis Obispo once a year for a military radio collectors meeting and one or more steaks at Jocko's. -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: Documation card readers for sale
On Jun 17, 2015, at 7:43 PM, Mark J. Blair n...@nf6x.net wrote: Are the readers in question these ones in Canada? When you drive up there to get them, you can stop by my house on your way home and drop one off. I’m in Sacramento so I’m right on the way. I’ll let you play some air hockey while you’re here! :-P -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com
Re: RK06 alignment pack
On 06/17/2015 11:56 AM, Johnny Billquist wrote: On 2015-06-17 18:36, Pontus Pihlgren wrote: How was alignment packs produced? As far as I know, in special machines mounted on slabs on stone weighting tons, standing on dampeners, so that you had absolutely vibration free environment, and then a very precisely controlled head control system that could write the tracks at the exact place they should be. I think the alingment packs even have some tracks intentionally offset from true center in order to check signal strength when heads are slightly off track as well. These pack formatters used air bearings to give the most vibration-free rotation of the spindle. They were generally pretty open units, not like disk drives, and were run in clean rooms by people wearing low-dust overalls. Jon
Re: Documation card readers for sale
I haven't replaced the rubber rollers on my M1000, yet. They're still in good shape. On Wed, 17 Jun 2015, couryho...@aol.com wrote: Mike where did you get new rubber roller things for the card reader? Thanks for the link on theinterface. Ed# _www.smecc.org_ (http://www.smecc.org) In a message dated 6/17/2015 7:21:15 P.M. US Mountain Standard Time, mloe...@cpumagic.scol.pa.us writes: On Wed, 17 Jun 2015, Kyle Owen wrote: On Wed, Jun 17, 2015 at 7:14 PM, John Ball ball.of.j...@gmail.com wrote: About six months ago I struck a deal with a place down in California for four Documation M1000's that I've been able to tell so far they all work but I really don't have space for more than one. If anyone here does get one, I've got a simple Arduino UNO program that interfaces to the parallel output and sends fully decoded information over USB at quite high speeds. The M-1000-L is a great reader, very reliable, and easy to work on too (I did a little routine maintenance, but mine was in 100% working shape when I got it). Here's a video: https://www.youtube.com/watch?v=N27Mr199I7g There's also Brian Knittel's USB interface for the Documation readers: http://media.ibm1130.org/sim/cardread.zip I built one, and it works well. Mike Loewen mloe...@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/ Mike Loewen mloe...@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/
Re: Documation card readers for sale
On Jun 17, 2015, at 16:14, John Ball ball.of.j...@gmail.com wrote: About six months ago I struck a deal with a place down in California for four Documation M1000's that I've been able to tell so far they all work but I really don't have space for more than one. I've been trying to sell them at a loss for months now over on the Vintage Computer Forums and Nekochan (if you got here you'll find pictures) but no bites. I swear there were people out there that were looking. Where did you folks go? Might anyone here be interested? I absolutely refuse to put them on the curb. Are the readers in question these ones in Canada? http://www.vintage-computer.com/vcforum/showthread.php?45888-FS-Documation-M1000-Card-Readers If so, the presumed cost of shipping is the main thing that has kept me from adopting one of them. Well, that and being in debt at the moment from other recent acquisitions. And not having a clear space to set one down. And not having a keypunch, let alone room for a keypunch in my tiny little packed-full house. But I do think they look quite cool! And if I find solutions to all of those impediments before you find loving homes for all of those readers, I may yet adopt one of them. I was born just late enough to miss using punched cards, so I think that experiencing them would be fun since I've never learned otherwise by needing to use them in anger. -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: OT? Compaq 5/60M
I'd consider it OT ... I miss my IBM 9595 ... with the P60 processor complex ... I thought it was doubly cool since the CPU was one of the examples of the Pentium that got shipped with the FDIV bug ... great machine to play with WNT 3.51/4, or OS/2 3.x or 4.x. I wouldn't say the P5 killed workstations or midrange ... they had maybe 10-15 years yet to move and shake when the P5 first hit the market ... but I suppose you are right in that it was probably the first shot across the bow. But time marched on, and now all you see in a full-size computer is x86_64. Ho hum ... :| Best, Sean On Wed, Jun 17, 2015 at 2:35 AM, Pontus Pihlgren pon...@update.uu.se wrote: Run of the mill PC clones are rather booring. But brand names, oddballs and first are always fun. I wouldn't mind to have the first DELL machine in my collection. I have a DECpc 433 with matching SCSI expansion box. A desktop machine with some interesting solutions. /P On Wed, Jun 17, 2015 at 12:43:17AM -0400, william degnan wrote: I know I keep pushing the boundary of vintage lately but I wanted to report to those who care that I finally got my hands on a 1993 Compaq 5/60M - this is a if not the first desktop computer with a Pentium processor installed stock. it was the 1993 dream machine - $9000+ It had an EISA bus and was otherwise a 486 system with a Pentium controller card, not on the motherboard. Pentium computers' contribution to the WWW era vintage is extremely significant. Pentium killed the minicomputer, or at a minimum merged into it, if you ask me. The interplay between DEC/Compaq/HP/Intel 1992-1995 culminating into the launch of Pentium processor systems is vital to understanding the WWW era of computing. How these companies worked or did not work together and how the Pentium vs. the Alpha processor came to be...a good tale of woe and $$. For those interested: Compaq 5/60: http://vintagecomputer.net/browse_thread.cfm?id=612 I have a bunch of articles to post on my site related to the first Pentium desktops which I will do asap. Bill P.S. while we're on this off-sh topic I also posted some photos of a Digital 486 laptop, DEC had a 486 laptop before it was absorbed by Compaq. 1994. Not really noteworthy other than the Digital name http://vintagecomputer.net/browse_thread.cfm?id=613 P.S.S. and related to Pentium and DEC ... here is one of DEC's early (but not the first) Pentium machine http://vintagecomputer.net/browse_thread.cfm?id=585
Re: using new technology on old machines. Was: PDP-12 Restoration at the RICM
On Mon, Jun 15, 2015 at 10:14:18PM -0700, Mark J. Blair wrote: On Jun 15, 2015, at 21:59, tony duell a...@p850ug1.demon.co.uk wrote: Even though there are at least 4 different USB connectors Ok, you got me there! When I was working for a GPS startup, I used mini-B on everything I designed with USB (always devices, never hosts, and no need for USB OTG). Then we got bought by a cell phone company and now everything's a godawful mix of mini-B and micro-B, with OTG thrown in there, too. Grrr! Well, micro-B is the better choice since it is designed for more plug cycles than mini-b, designed to minimize wear on the socket and instead wear out the (cheap, easy to replace) cable and it actually locks in the socket, so is much less likely to slip out. I'm cursing everytime some device comes with a mini-B connector these days instead of micro-B. IMHO USB got round the problem of null-modem cables by making them impossible. Which to me is not an improvement. I guess USB is OK when it works (like plugging in a memory stick) but a right pain to debug when it doesn't. And having read the standard there is much I dislike about it. Maybe this isn't the best time or place for this particular rant, but in my opinion, Windows' implementation of USB is fundamentally broken. It's a mouse, you stupid computer! You shouldn't need to spend a minute or more installing a new device driver for it! And you shouldn't need to install the driver yet again if I poke it in a different hole than I did last time! Every other *** OS on the planet is smart enough to say Oh, a mouse! I know how to use those! within a handful of milliseconds! Windows does what (haven't used a Windows box for a long time)? Now that is retarded. I'm used to my systems (Linux, *BSD) just going oh, this is a keyboard/mouse, no problem, I can handle this and stuff quietly works. Kind regards, Alex. -- Opportunity is missed by most people because it is dressed in overalls and looks like work. -- Thomas A. Edison
Re: OT? Compaq 5/60M
IIRC, they shipped that QVGA card you show on your Compaq P60 page with the DECpc AXP 150, too, no? Man that thing was awful ... I always lusted after the better card they shipped on that machine (don't recall) that could do 24-bit. I miss that box too ... ah, nostalgia. Best, Sean On Wed, Jun 17, 2015 at 10:54 AM, Sean Caron sca...@umich.edu wrote: Ha, I need to just stop using OT since it's ambiguous. On topic, on topic! :O Best, Sean On Wed, Jun 17, 2015 at 10:54 AM, Sean Caron sca...@umich.edu wrote: I'd consider it OT ... I miss my IBM 9595 ... with the P60 processor complex ... I thought it was doubly cool since the CPU was one of the examples of the Pentium that got shipped with the FDIV bug ... great machine to play with WNT 3.51/4, or OS/2 3.x or 4.x. I wouldn't say the P5 killed workstations or midrange ... they had maybe 10-15 years yet to move and shake when the P5 first hit the market ... but I suppose you are right in that it was probably the first shot across the bow. But time marched on, and now all you see in a full-size computer is x86_64. Ho hum ... :| Best, Sean On Wed, Jun 17, 2015 at 2:35 AM, Pontus Pihlgren pon...@update.uu.se wrote: Run of the mill PC clones are rather booring. But brand names, oddballs and first are always fun. I wouldn't mind to have the first DELL machine in my collection. I have a DECpc 433 with matching SCSI expansion box. A desktop machine with some interesting solutions. /P On Wed, Jun 17, 2015 at 12:43:17AM -0400, william degnan wrote: I know I keep pushing the boundary of vintage lately but I wanted to report to those who care that I finally got my hands on a 1993 Compaq 5/60M - this is a if not the first desktop computer with a Pentium processor installed stock. it was the 1993 dream machine - $9000+ It had an EISA bus and was otherwise a 486 system with a Pentium controller card, not on the motherboard. Pentium computers' contribution to the WWW era vintage is extremely significant. Pentium killed the minicomputer, or at a minimum merged into it, if you ask me. The interplay between DEC/Compaq/HP/Intel 1992-1995 culminating into the launch of Pentium processor systems is vital to understanding the WWW era of computing. How these companies worked or did not work together and how the Pentium vs. the Alpha processor came to be...a good tale of woe and $$. For those interested: Compaq 5/60: http://vintagecomputer.net/browse_thread.cfm?id=612 I have a bunch of articles to post on my site related to the first Pentium desktops which I will do asap. Bill P.S. while we're on this off-sh topic I also posted some photos of a Digital 486 laptop, DEC had a 486 laptop before it was absorbed by Compaq. 1994. Not really noteworthy other than the Digital name http://vintagecomputer.net/browse_thread.cfm?id=613 P.S.S. and related to Pentium and DEC ... here is one of DEC's early (but not the first) Pentium machine http://vintagecomputer.net/browse_thread.cfm?id=585
Re: RK06 alignment pack
Microdata had a setup they used for packs, then later for writing servo platters for their Reflex winchester drives. Similar to this system someone made a video of on youtube https://youtu.be/p4v7RRadC8E The electronics, optics, lasers and control heads show up on ebay from time to time. The microdata unit was actually a version which output control signals, rather than a measurement head like this video, so that their logic could step the positioner. Write logic which was not part of the drive was used when it was in manufacturing mode to write the servo on the drive before shipment. For testing there was a cleanroom setup for testing, usually when working on heads and evaluation of media. thanks Jim On 6/17/2015 10:05 AM, Noel Chiappa wrote: On a special rig, I'm pretty sure. I don't know how the RK06 alignment pack works, but I am familiar with the RK05 (our machine had them, and we had to realign one after a head crash), and I assume it's probably similar; it had to have been created on a special rig (the exact nature of which I don't know, but I know a normal drive couldn't write it).
Re: using new technology on old machines
The M452 module schematic for quick access for anyone following along, as it hasn't been linked before in the thread: http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/modules/mSeries/M452.pdf
Re: OT? Compaq 5/60M
Run of the mill PC clones are rather booring. But brand names, oddballs and first are always fun. I wouldn't mind to have the first DELL machine in my collection. I have a DECpc 433 with matching SCSI expansion box. A desktop machine with some interesting solutions. /P On Wed, Jun 17, 2015 at 12:43:17AM -0400, william degnan wrote: I know I keep pushing the boundary of vintage lately but I wanted to report to those who care that I finally got my hands on a 1993 Compaq 5/60M - this is a if not the first desktop computer with a Pentium processor installed stock. it was the 1993 dream machine - $9000+ It had an EISA bus and was otherwise a 486 system with a Pentium controller card, not on the motherboard. Pentium computers' contribution to the WWW era vintage is extremely significant. Pentium killed the minicomputer, or at a minimum merged into it, if you ask me. The interplay between DEC/Compaq/HP/Intel 1992-1995 culminating into the launch of Pentium processor systems is vital to understanding the WWW era of computing. How these companies worked or did not work together and how the Pentium vs. the Alpha processor came to be...a good tale of woe and $$. For those interested: Compaq 5/60: http://vintagecomputer.net/browse_thread.cfm?id=612 I have a bunch of articles to post on my site related to the first Pentium desktops which I will do asap. Bill P.S. while we're on this off-sh topic I also posted some photos of a Digital 486 laptop, DEC had a 486 laptop before it was absorbed by Compaq. 1994. Not really noteworthy other than the Digital name http://vintagecomputer.net/browse_thread.cfm?id=613 P.S.S. and related to Pentium and DEC ... here is one of DEC's early (but not the first) Pentium machine http://vintagecomputer.net/browse_thread.cfm?id=585
RE: using new technology on old machines
That's only the schematic. The link I included earlier:- http://dustyoldcomputers.com/pdp-common/reference/drawings/modules/m/m452.pd f also includes the PCB component layout, from which I inferred the Trim Pot is of the 10-turn variety. Dave -Original Message- From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Brent Hilpert Sent: 17 June 2015 09:28 To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: using new technology on old machines The M452 module schematic for quick access for anyone following along, as it hasn't been linked before in the thread: http://bitsavers.informatik.uni- stuttgart.de/pdf/dec/modules/mSeries/M452.pdf
Re: using new technology on old machines
From: Dave G4UGM I found it easier to think of it in DC terms. So the Cap charges through R5 + R3 and R9 + R8. As the Cap charges the voltage on the base of Q1 rises until it turns on, which then turns on Q2. At this point the cap is then charged (or discharged) in the reverse direction via Q2, D5 and R4 until Q1 turns off. I'm clearly never going to be any good at analog stuff! ;-) Even with what looks (on the surface) to be a wonderfully clear explanation of how the circuit works, I still can't really grok how it operates! I mean, I can tell from the polarity on the cap that the collector of Q2 must be at a higher voltage than the base of Q1, but I am utterly failing to understand how the cap discharges through Q2. And as the cap charges (i.e. the voltage across it increases), how does the voltage on the base of Q1 increase - surely it must be decreasing (since it's tied to the negative side of the cap, which is experiencing a voltage increase across itself)? Like I said, I apparently don't have the gene for analog... :-) Noel
RE: using new technology on old machines
-Original Message- From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Noel Chiappa Sent: 17 June 2015 15:08 To: cctalk@classiccmp.org Cc: j...@mercury.lcs.mit.edu Subject: Re: using new technology on old machines From: Dave G4UGM I found it easier to think of it in DC terms. So the Cap charges through R5 + R3 and R9 + R8. As the Cap charges the voltage on the base of Q1 rises until it turns on, which then turns on Q2. At this point the cap is then charged (or discharged) in the reverse direction via Q2, D5 and R4 until Q1 turns off. I'm clearly never going to be any good at analog stuff! ;-) Even with what looks (on the surface) to be a wonderfully clear explanation of how the circuit works, I still can't really grok how it operates! I mean, I can tell from the polarity on the cap that the collector of Q2 must be at a higher voltage than the base of Q1, but I am utterly failing to understand how the cap discharges through Q2. And as the cap charges (i.e. the voltage across it increases), how does the voltage on the base of Q1 increase - surely it must be decreasing (since it's tied to the negative side of the cap, which is experiencing a voltage increase across itself)? I think the cap is mildly abused. I believe that it is reverse charged. Like I said, I apparently don't have the gene for analog... :-) Noel
Re: RK06 alignment pack
On 2015-06-17 18:36, Pontus Pihlgren wrote: How was alignment packs produced? As far as I know, in special machines mounted on slabs on stone weighting tons, standing on dampeners, so that you had absolutely vibration free environment, and then a very precisely controlled head control system that could write the tracks at the exact place they should be. I think the alingment packs even have some tracks intentionally offset from true center in order to check signal strength when heads are slightly off track as well. Same kind of equipment was used to actually do the formatting of disks, as they cannot be formatted by the disk drives themselves. Johnny /P On Wed, Jun 17, 2015 at 11:39:25AM -0400, Noel Chiappa wrote: Anyone need an RK06 alignment pack: http://www.ebay.com/itm/Digital-Equipment-RK06-Aglinment-pack-/221803433215 Seems like something that should definitely get saved! Noel
Re: RK06 alignment pack
From: Pontus Pihlgren How was alignment packs produced? On a special rig, I'm pretty sure. I don't know how the RK06 alignment pack works, but I am familiar with the RK05 (our machine had them, and we had to realign one after a head crash), and I assume it's probably similar; it had to have been created on a special rig (the exact nature of which I don't know, but I know a normal drive couldn't write it). For the RK05, the alignment pack has alignment tracks with alternating sectors written a couple of thousandths of an inch offset from the track's nominal center line; when one watches the head's output on a 'scope (at a timebase sufficient to show pairs of sectors), if the output for both sectors in a pair is at the same amplitude, the head is correctly aligned. If not, it's easy to see on the 'scope - one has higher output than the other. Noel
Re: RK06 alignment pack
How was alignment packs produced? /P On Wed, Jun 17, 2015 at 11:39:25AM -0400, Noel Chiappa wrote: Anyone need an RK06 alignment pack: http://www.ebay.com/itm/Digital-Equipment-RK06-Aglinment-pack-/221803433215 Seems like something that should definitely get saved! Noel
Re: RK06 alignment pack
On Wed, Jun 17, 2015 at 11:39:25AM -0400, Noel Chiappa wrote: Anyone need an RK06 alignment pack: http://www.ebay.com/itm/Digital-Equipment-RK06-Aglinment-pack-/221803433215 Seems like something that should definitely get saved! That's AMAZING! I never had RK06es (just RK07s -- DM has them now), but I hope someone somewhere does and you'll *never* find an alignment pack on purpose when you need it. The price is great, even with international shipping. John Wilson D Bit
