Tony Duell wrote:
I can't comment on whether it's possible to make reliable, long-lasting,
devices with lead-free solder (although there seem to be exemptions for
what I'd call 'critical' applications (military, aerospace, medical, etc)
in the UK regulations which allow the use of leaded solder for such
devices, so draw you own conclusions).
----------------
I've put a call into a specialist friend who does mil-spec here. Last time
I talked to him he said they couldn't use lead based. In fact most of his
"hardened" designs had to be laser welded. But I want to verify what US
mil-spec calls for currently.
-------------------
But I can assure you I've had
enough dry joints in modern stuff assembled with lead free solder to last
me a lifetime. I've even had brand-new stuff that's had to be resoldered
before it will work.
And I've met plenty of other repairers (entusiasts and professionals) who
have had the same problems.
> producer of PCBs has had more than 5 years to move to lead free =
> environment.
> That was not a difficult change for competent manufacturing engineers to
> make.
>
> Yet, I think this is the third or fourth time you've brought this up. =
> You
> must have had a bad experience someplace and are judging the technology =
Not 'a' bad expeience, but many of them.
> by
> that experience. I know a lot of hobbyists, as well as lab technicians, =
> were
> annoyed at having to buy new soldering equipment for higher temperature
> boards.
I can't see what a hobbyist would have to bother -- at least in the UK,
these directives only apply to equipment that's offered for sale. You cna
do what yuou like in stuff you build for yourself.
----------------
Like you, many hobbists want to repair or modify equipment they buy. And
even more simple users like myself, where I buy PCBs and salvage the parts I
want. For example, I found some boards with 10 nanosecond 32Kx8 RAMS that
were perfect for a logic analyzer I want to build. A bitch to get off, even
though surface mount. Wish they were some of those bad joints you see -
these almost had to be cut off.
-------------------
>
> But the world has moved on. Lead free soldering is as good and in many
> cases better than lead based soldering. On the data from more than 100
> million lead free PCBs, I can attest dry solder joints are not a =
> problem.
>
> As for the cheapest plastic imaginable, I just don't see that in the
> marketplace. My current assignment is working with DVRs, STBs and TVs =
Perhaps your consumer electronic devices are built a lot better than
ours.
THis all started with a mention of a $89 VCR. Over here that's a '50 quid
VCR' and yes, we get them at that sort of price. Now, when I last bought
a VCR, some 15 years ago, it cost nearly \pounds 1000 (or 20 times as
much). Are you seriously telling me that, even though there's been
inflation in that time, a modern 50 quid machine is going to be as well
made anf as long lasting. Becasue I simply don't see that.
> using
> disk drives. So I always have a couple of dozen units torn down on my
> bench. What I see are vendors that have had 20+ years to refine their
> design, their processes and their materials. I see components and =
> systems
> that have an order (or orders) of magnitude better reliability than the
> products of 20 years ago.
I think the big change is that 20 years ago there was good stuff and bad
stuff out there. I mentioned I'd paid \pounds 1000 or so for a VCR. There
were much cheaper machines around at the time, sure, and they probably
have not lasted 15 years. But if you wanted to spend the money you could
get one that lasted, that was maintainable (the manufacturers not only
produced an excellent servive manual, but they sent it to me free of
charge when I asked about it), etc. Now I see \pounds 50 VCRs and \pounds
20 DVD players and nothing else. I'd love to be able to spend more money
and get a better machine, but I can't.
>
> This "everything old is good, everything new is crap" is not verified by =
> the
> data from the industry world wide. Some things do improve with time.
> Especially in a cut throat competitive industry where warranty costs =
> from
> poor products will put you out of business in weeks. Customers (and in =
> the
> US, laws) demand reliable products. Companies don't survive if they =
Not over here they don't. People upgrade because a new model is available
with more features (they they probably will never use). Provided the
machine lasts for the warranty period the manufacturer is happy. If it
fails after that time he gets to sell another one.
------------------------------------
This is one area I will agree with you. My experience at Philips exposed me
to the enormous difference in consumer protection laws in the US versus the
rest of the world. Philips management had a terrible time dealing with
these differences.
For example, if a box is even opened here, the unit automatically becomes
"used" and has to be marked as such. (Usually referred to as white
labelling.)
Customers can return a product without giving any reason. It doesn't have
to be a failure.
Cosmetic damage consititutes a failure. This includes the packaging.
Another huge difference is that refurbished units have to be sold as used,
even if they have a new product warranty. (Philip's answer was to sell the
reburished units through the employee stores.) This is also true if the
unit was refurbished before it ever left the factory. Of course that rule
is ignored by everybody. But big accounts like Apple and Dell still insist
that no unit can be reworked. They demand only prime yield product.
All of these laws were different from the typical consumer protection laws
in Europe. There, many manufacturers used a 5% rule. 5% of what they ship
is defective. They give the distributors extra units as a margin against
returns. Sadly, many of the returns are sold as new. There are no laws in
the Common Market to prevent this.
Management used to this Euro environment had a terrible time adjusting to
the US conditions. Some couldn't even understand the concept of a rebate:
if you advertised a rebate, you have to pay it! That lesson cost several
European companies tens of millions of dollars and government law suits to
learn.
One result of these differences is that European companies normally don't
normally thrive in the US. The cultural gap in business is too great. When
I went to work for Philips, no one I knew here was aware Philips made
anything besides light bulbs. It is not a well known brand name here, like
Sony and Panasonic.
So I can accept that you see a much lower level of quality than is normal
here in the US. We still see some crap, but we can do something about it.
---------------------------
> Tony, you have your preferences and choices and more power to you. But =
> if
> you did a study of current state of the art electronics, you would find =
> it
> to be far superior to that of 20 years ago. Even if it won't provide a
> maintenance manual.
Sorry, I have looked at modern stuff and found that in many cases the
performance and quality of construction is markedly inferior to that
which I already own.
Perhaps you could explain to me in what ways I am going to find it
'superior'.
-tony
---------------------
Tony, your heart and mind are in the past. No matter how many facts,
figures, statistics I present, I will never convince you that today's world
is as good as your golden age when everything was perfect. Why bother?
It's just unpleasant for both of us.
I've spent 46 years in the electronics industry, always on the cutting edge,
and always striving for improvement. I see enormous changes, most for the
good. You don't.
I value my time too much to waste it on repairing minor appliances. You get
great pleasure from that activity.
We are never going to agree on what constitutes a good product - you want a
maintenance manual and lots of spares; I want no failures and no hassles
during a useful life cycle.
I think we agree on a love of old computers and the need to keep a few
alive. And we may share pleasure in designing and building little systems.
But I wonder if you enjoy playing with PICs and FPGAs like I do, since
little documention on the innards is available.
And I know we disagree strongly on use of the internet, saving old manuals
and sending photos, scans, software etc. That requires technology you are
not willing to embrace.
I have to admit I'm hoping to meet you next year. I'll be retiring then and
we are going to spend half our time in Colechester and the other half in
California. We are going to explore a lot of England that I still haven't
seen. And attend a few science fiction conventions, hit the famous book
stores in Wales, check out pub food, sample the local beers and in general
do the things we always wanted to do but were too busy.
Billy
Hello,
Would you please post the following message.
I am looking for someone who can copy 1702 EPROM's. Contact me at
Fixer7526 at wmconnect.com .
Thanks,
Alan
I've got a Kennedy 9000 9-track tension-arm tape drive (800/1600 bpi
dual density) installed in a 5-foot tall rack. The rack has side and
back panels as well as some covers for the front.
The drive was working a few years ago so it's complete but I have no
idea if it's still OK. I've got the documentation including print sets,
etc.
It's available free for pickup in the Fairfax county Virginia area.
We'll need to remove the drive from the rack to get it out of the
basement unless you bring some help :-)
-Rick
Haven't decided what to do with it yet.
Got a DEC VT240, no monitor, no keyboard. free for shipping.
Got a VAXSTATION 3100 model VS42??, there is a crack on the face panel.
Looks good other than that crack. No disks. Free for shipping.
vax, 9000
--- Brent Hilpert <hilpert at cs.ubc.ca> wrote:
> Billy Pettit wrote:
> >
**>> snip <<**
>
> I have a web page
> (http://www.cs.ubc.ca/~hilpert/e/gates/index.html)
> where I'm accumulating the diversity of symbols th
at
> have been used for
> logic gates. If you have a scan or reference for t
he
> Cray/6600 symbols I'd be
> interested in adding them.
>
Thanks for posting that.
Regards,
Andrew D. Burton
aliensrcooluk at yahoo.co.uk
The simplest distinction between HP2000 F and Access is that, F and everything prior (As I recall) used KILL-name (or KIL-name) to delete a program so that one could save a new version of it. Access changed that to PURGE-name (or PUR-name) for better "Political Correctness". I even remember that the system at Laurel HS in Laurel MD "Patti", made this change in the summer of 1976.
Does ether "kill" or "purge" ring a bell to you, Richard?
I see many people telling wonderful stories about HP2000 systems. If some of the others could also share with us where the systems were located, someone else in the group may also remember some of them.
Three of the original HP2000 operating systems are running under SIMH, version E, F, and Access. If anyone is interested in booting up a real HP2000 TSB OS on simulated hardware (E should run on Unix, all three should run on Windoz), you may want to checkout:
http://tech.groups.yahoo.com/group/hp2000family/
The links to the E and F Zips are in the links section of the group. The group is a good place to ask support questions about the OS or the simulation. New members are moderated to prevent spam bots from spamming us. If I can tell that you're a real person I'll take that off as soon as I see it, or you can call it to my attention by email. The Access Zip STILL has a real backup of a real system on it (sorry about that). So it is available by request.
On the subject of Z999, I seem to recall that at least some of the systems before Access even had the HELLO program residing in Z999. As far as I have seen in the Access source Z999 no longer had any special privelages.
Someone asked about backing up TSB E without a tape drive. The 7900 disk drive had one fixed platter and one removable platter. The system and A000 library was on the fixed platter, and user catalogs were on the removable platter. To backup, you first shutdown the Timeshare System. Then remove the top disk platter cartridge (containing the user libraries). Put a scratch cartridge in and copy the fixed disk to it. Then put the user data cartridge back in and copy it to the fixed disk platter (trashing your system disk). Then put in another scratch disk and copy the user data from the fixed disk to the removable disk. Then, put your backup of the system data back in, restore the fixed disk, then put your user pack back in and start up the timeshare again. Presto, you now have a backup removable platter containing a copy of the system platter and another with a copy of the user data.
If course, when running on simulated hardware, tape drives are free, so we usually backup even TSB E to tape image files. The TSB E OS was distributed on two paper tapes, with a third tape for the loader. The ZIP files for the simulator contain images of the original paper tapes. Remember, the simulator is only simulating the hardware. Even on Access we are using an image of the original paper tape bootstrap to get the system running. The original operating systems don't know that they are not running on real hardware.
Even for someone interested in building a real system, having access to all of the binaries and documentation in one nice neat package that is freely available and will even boot and run on a laptop, should be a helpful tool. It can help you get used to the system operator, system administrator and system analyst roles before you get your real hardware running. And besides, it's fun to "telnet 127.0.0.1" and do a CR LF CR LF and see "PLEASE LOG IN".
If anyone knows or may be able to track down anyone who may still have an old HP2000 system back up tape, we would love to hear about it. We have had great success reading and reloading old tapes under simulation.
Hope this helps,
Mike Gemeny
A Cylinder is not a single point; it's the collection of multiple tracks
that are all under the read/write heads whenever the heads are positioned
over that cylinder. It exists only because there are multiple heads.
However, while a double sided floppy drive does have cylinders, some systems
did not take advantage of them and accessed the floppy drive using all of
one side first, then all of the other side, rather than using cylinders
(rather than tracks) sequentially. Both types of access are possible, and
cylinder based access is clearly "better", but not all systems worked that
way.
Message: 31
Date: Fri, 22 Dec 2006 06:59:35 -0600
From: Jules Richardson <julesrichardsonuk at yahoo.co.uk>
Subject: Cylinders versus tracks...
To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
Message-ID: <458BD6B7.8040100 at yahoo.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Out of interest, which is the correct terminology when defining a single
point
on a disk's surface - is it better to talk in terms of cylinders, or tracks?
People often seem to talk about floppy drives in terms of tracks, heads and
sectors (e.g. for an 80 cylinder floppy with two sides they'll still talk in
terms of tracks 1-80 in conjunction with a side number, even though the
media
has 160 tracks in total)
Talking in terms of cylinders seems to be generally the norm with hard disks
though, and perhaps seems a bit more sensible - but remember that hard disk
manufacturers are the people who introduced decimal megabytes into common
use :-)
Personally I prefer to talk in terms of 'surface number' rather than 'head
number', as a given surface could conceivably have more than one head in
order
to improve media latency - but I'm unsure as to whether to use
cylinder/surface/sector or track/surface/sector. It's all just semantics,
but
for the stuff I'm currently working on I'd rather go with the 'correct'
version even if that happens not to be the one most commonly used...
cheers
Jules
* Jules Richardson wrote:
Out of interest, which is the correct terminology when defining a single
point
on a disk's surface - is it better to talk in terms of cylinders, or tracks?
People often seem to talk about floppy drives in terms of tracks, heads and
sectors (e.g. for an 80 cylinder floppy with two sides they'll still talk in
terms of tracks 1-80 in conjunction with a side number, even though the
media
has 160 tracks in total)
Talking in terms of cylinders seems to be generally the norm with hard disks
though, and perhaps seems a bit more sensible - but remember that hard disk
manufacturers are the people who introduced decimal megabytes into common
use :-)
Personally I prefer to talk in terms of 'surface number' rather than 'head
number', as a given surface could conceivably have more than one head in
order
to improve media latency - but I'm unsure as to whether to use
cylinder/surface/sector or track/surface/sector. It's all just semantics,
but
for the stuff I'm currently working on I'd rather go with the 'correct'
version even if that happens not to be the one most commonly used...
cheers
Jules
--------------------------------------------------
Tracks was the original terminology when only one surface was used. For
example on some of the early single sided floppies. Cylinders were used to
describe a head switch to a new surface. The head switch would be very fast
(faster than a one track seek) so continuous data could be recorded on the
same track on different surfaces - in effect, a cylinder.
So tracks is accurate even on multiple surfaces. But cylinders implies that
data is written on all available heads before a seek is performed.
With the advent of the embedded servo, tracks no longer line up neatly. A
head switch may involve the new head seeking 10-100 tracks to get back to
the same track number. Current state of the art is ~150K tracks per inch.
So even a small difference is a lot of tracks.
And 1 track seeks are now very fast, so it is rare to see controllers doing
the cylinder concept.
Because the usage and language has changed with time, the use of cylinders
versus tracks depends a lot on the vintage of drive and controller.
Cylinders were the most efficient way to use an SMD era drive with a
dedicated servo surface. But they are performance lagging on today's
drives.
The amount of data on a track is variable and has been for many years. So
the drive is divided into zones, which have a different amount of bits per
track for each zone. Drives may have as many as 50 zones, ie 50 different
numbers of bits per track.
Modern drives often have a different number of tracks on each surface. So a
single platter drive could have 2 different track counts, one for each
surface.
Thus current state of the art drives can have a huge difference in the
number of tracks and amount of data on the surfaces. For example, a 100GB
single platter drive may have 44GB on one surface and 56GB on the other
surface. Because of this, you need a decoder program to even find what
track you on. Cylinder and tracks don't have much meaning at the interface
level.
Consequently, we normally use LBA - Logical Block Address - and don't pay
much attention to tracks or cylinders. Except when trying to physically
view of certain spot on a disk.
Billy
Lars Hamren writes:
Hi,
Computer Automation LSI-2 machines, of which I have two, used Pertec
D33xx drives, of which I have none. There is now a somewhat pricey
Pertec D3421 drive on eBay. The $500 question is: will this drive
interface to my systems?
Does anyone have documentation on Pertec 33xx and 34xx disk drives?
Does anyone know if 34xx can drives be used on systems designed for
33xx?
Regards
/Lars
-------------------------------------------------------------------
Lars Hamr?n Tel...: +46( 46)189090
Svensk Datorutveckling Mobile: +46(705)189090
Vadm?llan 211 e-post: hamren at sdu.se
S-225 94 Lund WWW...: www.sdu.se
Sweden
