On 2012-07-16 06:27, "Jerome H. Fine"<jhfinedp3k at compsys.to> wrote:
> It is obvious that we disagree on my basic premise - that internally,
> sufficient
> bits be available to represent the date starting at a date far enough in
> the past
> to handle many old dates in the countries which would use the operating
> system. Some operating systems such as VMS achieved most of that
> goal. On OS/8, Unix and RT-11, as just a few examples, it would have
> required a decision to double the number of bits over what was actually
> used.
What I think we seem to disagree on is the idea that this could ever be
solved in the general case.
You always will have some restriction on dates in a computer system. So
the question becomes what would be reasonable restrictions.
For a system like OS/8, I think that the original design, using only 3
bits for the year was a little too little, but the extension made, which
added two more bits, allowing a range of 32 years was more than
reasonable, given the right requirements for memory usage on PDP-8
systems in general.
Doing something equally complex as can be done on a PDP-11 would not be
justifiable on a PDP-8.
PDP-11, then again, have issues which means the solution used on VAXen
was not really justifiable.
To reiterate - on a VAX running VMS, the date is kept in modified julian
date, using 100ns increments stored in an 64 bit integer.
Using 64-bit values, and doing arithmentic on them, is not cheap on a
PDP-11, nor very nice from a storage point.
Now, RSX eventually did support most of this, but it's not something for
weak machines, and it's still a pain.
Unix choose 32-bit integers, counting seconds since 1970. Also a rather
restricted range, and yes, it will run out in 2038, or something like
that (someone else can look up the specifics, it's widespread, and
simple to calculate yourself if you want to).
However, it was a reasonable choice for Unix when initially done on a
PDP-11.
Storage was important, more so in the age of the PDP-8. Every single bit
was counted. You did not waste a whole word. To do so was horrible.
Good code managed to squeeze a bunch of instructions into also being
data, thus reusing bits whenever.
> For OS/8 and RT-11, the simple solution would have been to use half a
> word for the month and day (not sure what half a word is called on a PDP/8)
> and a full word for the year.
Half a word would still be half a word. And such a waste as you suggest
would never have been acceptable on a PDP-8.
> Probably, the question of having adequate support for the date was the
> real decision. I have seen multi-million dollar systems which ignore the
> date (like a micro-wave) and only provide the time. But if there is a
> disk drive with files and dates to be noted when the file was created
> and at least modified (and perhaps referenced), then there can always
> be a reason to use dates on some files which precede the start of the
> operating system - to note when the information within the file was
> actually created is just one possibility.
>
> If this above basic premise is not considered adequate to justify allocating
> a word in memory for the year rather than 5 bits in the case of RT-11
> (eventually 7 bits to manage dates from 1972 until 2099) and however
> many bits were used in OS/8, then there is really no point in this
> discussion.
OS/8 use 3 bits for year in a file date. It was never extended. However,
two more bits was inferred based on the current date. Often works well
enough, but files older than 8 years old will display wrong.
And yes, using more bits than this was not considered acceptable at the
time.
> In respect of such vital information as the date, saving a few bits was not
> justified in my opinion. The fact that VMS arrived later than OS/8 and
> RT-11, but allowed dates much before VMS was ever released suggests
> that DEC had begun to realize that the date was important. The same
> with RSX-11.
I think it's fair to say that it has always been understood that there
are times when you want to represent larger date ranges, but it's a
tradeoff that has to be made. And for systems like OS/8, the tradeoff
was done the way described above, and I think that it was a reasonable
decision.
Only with VMS was storage and processing powers becoming cheap enough
that you could really afford to be more generous.
RSX date format do indeed give a really large range, and is very
wasteful of bits. But that was done to keep processing to a minimum. So
there is a good reason for the RSX choice as well. The RSX format is a
headache if you want to do some kind of things, but for what the kernel
uses it for, it's really simple.
> >Johnny Billquist wrote:
>
>>> > >On 2012-07-13 19:00, "Jerome H. Fine"<jhfinedp3k at compsys.to> wrote:
>> >
>>>> >> >Johnny Billquist wrote:
>>> >>
>>>>> >>> >[Snip]
>>>>> >>> >Ooo. So TECO-8 actually lie in their documentation... Even worse.
>>>>> >>> >A year in the range 1986-1994 would just have looked like 1970-1977.
>>>>> >>> >That's ugly of them.
>>> >>
>>> >>What seems even more evident to me is that DEC took
>>> >>(as most other companies did as well) the attitude that
>>> >>even the internal representation of date and time was
>>> >>not important enough to allow the same information to
>>> >>be exchanged between operating systems on a consistent
>>> >>basis.
>> >
>> >Sorry, but I fail to see the point. The internal representation of a
>> >date will almost by necessity be different between different OSes and
>> >hardware. Having a bunch of 16 bit values represent a date on a PDP-8
>> >would be incredibly stupid and difficult, not to mention that OS/8
>> >have no concept of time to more detail than a day. And even that needs
>> >to be updated manually every day.
> Your assumption differs from what I would suggest - see above.
I'm not sure it's an assumption difference. I think I made an
observation. Maybe if you point out what assumption I made, then I can
comment on it...
>> >So, ignoring the internal format, which can't really be portable
>> >anyway, you then get to representation. There will always be dates
>> >that cannot be represented in whatever format you choose. So what is
>> >the point of bringing up that argument? It is nice if the dates that
>> >you might reasonably expect to be processes be possible to express on
>> >the system. As for communicating with other systems, in the
>> >communication I would suspect/expect that you use an intermediate
>> >format (a nice text string for example) that both agree on. And then
>> >you can convert from the internal format to and from this intermediate
>> >format, as long as the date is within a range expressable on that system.
> That would be one solution, but other solutions are available. The
> most important point is to have sufficient internal bits to start with.
As I have already noted that there can never be "sufficient number of
bits", let's skip that part. I also pointed out that the internal format
cannot be the same within all OSes, running on different architectures.
If you disagree on any of these two points, let me know, and we can have
a discussion about those.
Assuming you agree with the above, then there is no avoiding going
through some intermediate form when communicating between different
systems. What other solution do you claim is possible???
>> >When you go outside the date range for the system, you can either try
>> >to do something reasonable, or give an error. I think that is a choice
>> >that is best left to the writers of the code to decide on a case by
>> >case basis.
> I agree - the point I attempt to make is to stress the requirement
> to have sufficient internal date range to start with - see above.
Ok. Let's back up here.
Are you suggesting a common internal representation of dates on all
systems? What range would you consider "sufficient"? Also, what format
would you propose that would be equal between all computers, having
different word lengths, different capable CPUs, different speeds,
different resolution clocks, and so on. And which is truly future proof?
>> >By the way, Unix express time as a number of seconds since Jan 1,
>> >1970, 00:00 UTC.
> Which I think provides a maximum year of 2038 if 32 signed bits
> are used. Far better would have been to use 64 bits with a
> higher resolution such as milliseconds and start at least as far
> back as 1900.
Except that today people are not really satisfied with millisecond
resolutions. Unix systems nowadays have things that goes to
microseconds, and soon I suspect people will start having issues with
that as well.
And dates before 1900 are definitely not unheard of.
>> >And time is horribly complex. You know that even if we keep it fairly
>> >modern, different countries switched from Julian dates to Gregorian
>> >dates at different times, the last being Russia, in the early 20th
>> >century.
> I am well aware of the nature of how complex the subject of dates
> and time can be. To start with, the Common Era (aka Gregorian)
> Calendar is not used as the primary date representation by even a
> majority of the Earth's population. However, with respect to using
> computers, the countries and societies which first started to use
> computers and the internet primarily use the Common Era Calendar
> and I would suggest that the only dates which early computers did
> support were Common Era (Gregorian) dates. I doubt that time
> zones were even considered at that early stage, let alone considered
> important enough to support internally, let alone externally. And
> even if Russia was considered important enough as a market for
> computer systems, I doubt that anyone would have remembered
> that the country adopted the Gregorian Calendar less than a
> hundred years prior.
>
> As for just how complex time actually is, the biggest problem
> that few people realize is that the length of the year can vary by
> many minutes from the average length of the year. I seem to
> remember that the variation can be about 15 minutes. Every
> so often, a leap second has been used to keep clocks synchronized
> with astronomical time (that UTC you mentioned above). The
> average person completely ignores that complexity, but now
> with the internet, operating systems must know the time very
> accurately. But the date is a completely different matter. At
> any one location, the date changes, on average, every 86,400
> seconds - except when a leap second occurs - and having a
> few extra bits internally to handle the year is, in my opinion,
> essential.
>
> So the initial decision for the internal representation of the date
> was the base date or earliest date to be represented. Many,
> probably a majority of operating systems used a very restricted
> choice which reflected the emphasis on using as little storage as
> possible. In my opinion, that was a bad choice.
You use what you have. Or don't use what you don't have in this case.
Which was memory. When memory was expensive, you did not waste it on
something you didn't really need. And having an over-expressive date
format would have been considered extremely wasteful.
I think it was a reasonable choice, and in fact the right choice at that
time. If I wrote a new OS for a PDP-8 today I would still not do
something overly complex or large in size. You simply can't afford such
a thing on a PDP-8.
>> >If you really think that you can come up with a reasonable, portable
>> >design, that is "universal", I think I know of a few organizations
>> >that would like to hear from you.
> A "universal" design would be to use Julian Days (just a count of
> the number of days from an agreed upon date - which has already
> been accepted by astronomers) instead of dates. Then, convert from
> Julian Days to whichever local calendar is favoured by the party
> using the date. But that has already been rejected by most societies
> and only a small percentage of the population are even aware that
> Julian Days exist. There are too many reasons for most societies
> to not use Julian Days - mostly religious in nature which requires
> a seven days cycle to support a holy day every seven days. The
> French attempted to start a new calendar, but failed - probably
> mostly on the seven day cycle.
VMS uses the modified julian day.
The french attempt at a 10 day week failed because people got upset when
they realized it meant less weekends. :-)
Not that 10 hours per day felt all that great either...
>> >Until then, I'm pretty much satisfied with things the way they already
>> >are. Yes, OS/8 have been broken for 10 years now. But to fix it
>> >require more than just changing the internal storage for the date.
>> >
>> >RSX got fixed, and depending on which bits you look, it might stop
>> >working right 2070(?), 2099, 2155 or 34667.
>> >
>> >I don't know about RT-11, but I do know that RT-11 is totally separate
>> >from RSX, and any problems are not shared, but unique.
> I noticed you are aware of the TECO discussion on dates for
> a number of different operating systems, so you probably
> already know.
>
> RT-11 will break on January 1st, 2100 in the same manner as
> OS/8 has already broken - there are no more bits in the date
> word to handle more than a range of 128 years starting in 1972.
>
> The only solution is the add additional storage to hold more bits
> for the year. Thus far, I know of only one other individual
> (who supports RUST) who is serious about adding those extra
> bits to the RT-11 file system, but there is no agreement as yet
> about how to do that. If no one else will even discuss the question
> of how dates for files in RT-11 can be used and extended beyond
> the year 2100, then eventually a unilateral decision will be made -
> or not as the case will be. Since it is probably not going to be
> very important for RT-11 to support dates after 2099 except
> for someone running RT-11 on an emulator (will any actual DEC
> hardware still be running after 2099), the matter is probably only
> of academic interest or only for hobby users - if any still exist
> in 2100.
Is file dates in RT-11 exactly the same format as system date?
In OS/8 they differ, since two additional bits were added to the system
date, but file system dates do not have that.
Apart from that, yes, RT-11 dates will indeed break at some point.
That's a problem in RT-11, which people who know and care about RT-11
needs to solve. And it is still a unique problem in RT-11. No point in
trying to involve RSX, Unix, VMS, or any other OS in that discussion.
Johnny
Does anyone here know of anyone who makes sets of napier's bones?
--
David Griffith
dgriffi at cs.csubak.edu
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
Guys,
Original email attached.
Two new thoughts:
a.. I do seem to have generated some strong interest for the 7090 documentation, which is good. And some controversy as to who should receive these bits: US or UK (perhaps Australia?). The 7090 was an American invention but this one was used in the UK.
Perhaps each of you with a strong interest could make a case to us for receiving this material. The decision of the deceased owner's family, the clearing team and myself to be final.
b.. Something which might influence decisions: the materials are paper, metal and plastic. The paper is slightly damp, the metal has corroded in some cases and the plastic has some mould patches. None of which make the material unusable in any way but I thought I must be clear on this point. I should have done so in the original email, sorry.
Kind regards,
peter vp
|| | | | | | | | |
Peter Van Peborgh
62 St Mary's Rise
Writhlington Radstock
Somerset BA3 3PD
UK
01761 439 234
|| | | | | | | | |
----- Original Message -----
From: Peter Van Peborgh
To: cube1 at charter.net ; michaelv at virginiairrigation.net ; henridhosty at hotmail.com ; IanK at vulcan.com ; cctech at classiccmp.org ; aek at bitsavers.org ; wdonzelli at gmail.com ; lin.jones at tnmoc.org ; scmobjectenquiries at ScienceMuseum.ac.uk
Sent: Monday, August 06, 2012 12:21 PM
Subject: To all with interest in IBM 7090
Guys,
I am sending this to all who have registered an interest in the IBM 7090 and museums. Sorry if I got some people wrong!
This computer started life at AWRE in the UK (nuclear weapons design?!) and finished in the Medical Computing department at Manchester Uni in 1970, where it ran for 10-20 years.
It had 4 channels, 32K memory, card reader, card punch, 300 LPM barrel printer and ?20 mag tapes. It also had an IBM 1401 for printer I/O.
I have now surveyed the stuff available. There is no hardware. It is a lot of (probably complete) hardware documentation, cicuit diagrams, s/w documentation (IBSYS, etc) also. Also a lot of mag tapes of mixed content and some card trays of mixed content.
Are any of you out there interested? It is all quite heavy so transport will be a challenge, but surmountable!
The stuff will be available in the first week of September. Any sensible offers will be considered. It might go on eBay but I will wait until you guys respond first.
Kind regards,
peter vp
|| | | | | | | | |
Peter Van Peborgh
62 St Mary's Rise
Writhlington Radstock
Somerset BA3 3PD
UK
01761 439 234
|| | | | | | | | |
Hmm. It looks to me like the metal with the black goo on it (which is
scraped off with a razor in the video) once had a piece of thin foam
glued to it.
Like many things made out of that type of foam, (i.e. keytronic
keyboards, and the anti-noise foam inside certain dec, sun, and other
older machines), the foam has turned into sticky goop after a number of
years (and probably exposure to ozone inside the printer), causing the
solenoid to stick.
Just a guess, since I don't have one of those nearby to take apart.
--
Jonathan Gevaryahu
jgevaryahu at gmail.com
jgevaryahu at hotmail.com
Hi Guys,
I posted this note on Vintage Computer Forums, and thought I'd see if
anyone could help here too.
T actually an acceptable looking TRS-80 Model 1 monitor I snagged for $3
but I figure the principles are the same regardless.
It's dead. No raster and no glow in the tube neck. The board does heat uo
though and there is that smell of old electronics being startled awake
after many years. I've done no tests yet, but I have Sam's Facts for the
model 1, and they provide a troubleshooting guide for the monitor and say
what voltages should be on cetain components. I suspect something to do
with the AC power supply of maybe horizontal sweep. Some faulty power
transistor maybe?
What I would appreciate from anyone who knows, is a link to a page or doc
which explains how composite B/W monitors work. The Sam's document is great
>from the perspective of troubleshooting detail but it does assume you know,
conceptually, just what's going on. I don't and I'd like to get some
understanding before I start poking around.
Incidently the SAM's fact PDF covers the 110V version while I have a 240V
one. There are some differences, one of which is there appears to be no
fuses in the AC circuits!
Thanks
Tez
Fellow cctalkers,
I rescued this lot from work before it was binned but I'm not sure how much
interest there'll be for it. Free as long as you pay shipping or collect
>from Cambs, UK:
1 Storageworks Command Console 2.1
Several 'Serverworks Manager' kits.
If nobody's bothered I'll take them to recycling.
Cheers!
--
Adrian/Witchy
Binary Dinosaurs creator/curator
Www.binarydinosaurs.co.uk - the UK's biggest private home computer
collection?
Dave
It's not the practicality of shipping it that's the issue, it's just my preference was for someone to turn up and take it away as it's the simplest option for me.
Selfish, I know. But it worked out for everybody involved...
Julian
On 03/08/2012 09:12, Dave McGuire wrote:
>
>?? Good grief, these are not large or heavy devices.? You know the TS05 is a little tabletop drive, right?? Not much bigger than a big PeeCee.
>
>????????????? -Dave
Hi guys,
I think this could possibly count as the longest of long shots, but I
figure it's at least worth a go :)
About a month ago, I picked up a Polaroid HR-6000 film recorder. This is
one of their "Digital Palette" series film recorders (of which the
CI-3000, CI-5000, HR-6000SE and ProPalette 7000 and ProPalette 8000 are
also members).
The machine works fine, as long as you run it on a Windows XP machine.
Even then, the software is finicky and prone to crashing out in strange
and mysterious ways. Being Windows, a reboot is usually required to fix
things. I'd like to see it working on one of my Linux boxen :)
I've managed to reverse engineer the Polaroid driver to the point where
I have a reasonably complete list of the basic SCSI commands and
sequencing required to get something output. However there are several
things I haven't managed to figure out - the huge stack of magic
numbers, for instance.
What I'm after (the Holy Grail so to speak) are either the header files
or the full source code for the Polaroid Interface Toolkit. This was an
SDK Polaroid used to give out free to developers back-in-the-day, and
nearly all the software I've seen was derived from it. A copy of this
and/or its accompanying documentation would likely answer the last few
of my questions about the command set and hardware.
I'm also interested in documentation and software for the Palette and
Digital Palette series - especially but not limited to:
- Parallel Port Interface Specification Manual
(probably useless, but may contain info useful for figuring out
more of the SCSI command data blocks)
- Digital Palette Product Specification Manual
- SCSI Parallel Interface Specification Manual
- the "Digital Palette Test Software" disk (GENTEST and DP2DIAG),
Polaroid part number / tool number 13437
For what it's worth, I also know software existed for the following
platforms:
- DOS (Polaroid Palette for DOS)
- Windows 3.1 (Zenographics SuperPrint for Polaroid Palette)
- Windows 95/98/XP (Graphx RasterPlus 95, now sold by Photogize for a
rather silly amount of money)
- Mac Classic (Polaroid Palette Export for Macintosh)
- Amiga (ASDG Art Department Professional)
- NeXT (eXTRASlide --
http://www.kevra.org/TheBestOfNext/ThirdPartyProducts/ThirdPartySoftware/In…
)
- Atari ST (can't find any evidence of this beyond Polaroid's
marketing materials)
Whether copies of any of this software (besides RasterPlus) still exist
is another matter entirely...
If you've got any of the stuff above (or anything else which could be
useful) please either reply here or send me an email.
Thanks again,
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/
My father worked in a mine in the '70s that was using a Honeywell 316 for process control. I was thinking it might be neat to see if I could track one down. What are they worth the days? How common are they?
Sent from my iPad
