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>> Files only on disk? Or on tape too?
>
> Obviously tape files were contiguous. I must be misunderstanding what
> you're asking.
From what little I've seen, with punch cards it's a case of "please
read this bunch of cards". You don't have filenames or anything.
Presumably on magnetic disk you have a file *system* which describes
logical files with names and things. I'm asking whether the same holds
for tape, or whether it's just treated as an endless stream of bytes (or
records or whatever).
>> OK. But does the system know where the *fields* in a record are? Or
>> just what size the records are?
>
> You compiled it into the program. Often when they weren't actually fixed
> size, they were fixed size anyway and padded (like cards). Or the size
> was stored in the header of the file.
Right. So it's a property of the program, not the system.
>> Yeah, I think the term "mainframe" is probably obsolete now. There are
>> probably more exact ways to describe what type of computer you mean.
>
> Could be. There's something clearly between "small" and "large" now.
Minicomputers! :-D
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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>> So it must have been possible to process larger datasets than that
>> somehow.
>
> http://en.wikipedia.org/wiki/External_sorting
See, now sometimes discussions can throw up interesting stuff - and it's
not all of purely historical interest. ;-)
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Darren New wrote:
> To be clear, they pretty much stopped making that sort of machine in the
> late 70s, but many of them lasted into the 90s before they ahd to be
> retired, often for lack of parts.
Now that's reliability engineering for ya.
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Orchid XP v8 wrote:
> I'm asking whether the same holds
> for tape, or whether it's just treated as an endless stream of bytes (or
> records or whatever).
Oh, I see. It depends whether you are using a labeled tape or an unlabeled
tape. I.e., that depends on the OS.
> Right. So it's a property of the program, not the system.
Again, depends on the OS. On the really primitive ones, it was a property of
the program. On the really modern ones, it's also a property of the program.
On the ones in between, they made it a property of the files.
--
Darren New, San Diego CA, USA (PST)
Ada - the programming language trying to avoid
you literally shooting yourself in the foot.
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Orchid XP v8 wrote:
> Now that's reliability engineering for ya.
Indeed. That's another important differentiation.
--
Darren New, San Diego CA, USA (PST)
Ada - the programming language trying to avoid
you literally shooting yourself in the foot.
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>> Now that's reliability engineering for ya.
>
> Indeed. That's another important differentiation.
Even today, I see people selling "servers" which are really like
"desktops". (1.2 GHz Intel Celeron with 512 MB RAM? I don't think so...)
I think the "real" difference between a desktop and a server is probably
fault-tolerance. When I first joined the 2-bit company I'm with now, we
had a server with a 500 MHz AMD Thunderbird CPU and 128 MB RAM. Now we
also had 4 GHz Intel Pentium IV workstations with 256 MB RAM in the lab,
which makes a bit of a mockary of the "server" tag. But the lab PCs
didn't have multiple Ultra320 SCSI HDs, hardware RAID controllers,
redundant PSUs or 30,000 cooling fans. But the "servers" did. ;-)
(Seriously, it didn't have 30,000 cooling fans, but it did have *a lot*
Probably way, way more than necessary, IMHO...)
The HP ProLiant I was briefly in charge of was really nice, actually. It
had a little diagram on the front showing the system board, and a little
red LED for every component on it for which a failure sensor exists.
It has ECC RAM, and yet it has multiple RAM banks, and it can compare
them and tell you if one RAM bank is faulty. (I gather this works in up
to a 4-way configuration, for 4x RAM redundancy, in case the ECC doesn't
catch it. Oh, and the RAM is hot-swap. HOT-SWAP!)
It also has more fans than it is sane for any one device to have...
although... it is quite a small form-factor, so maybe it does need it,
actually.
Also has hot-swap HD bays with indicator lights. The RAID software even
has a function to make the lights change colour so you can yank the
correct unit. (Nice!)
And as if all that wasn't enough, there's a second computer inside it
which you can use remotely to manage the server. Do stuff like see the
video output, control the keyboard and mouse, and even make the main
computer think there's a CD in the drive when really it's an ISO image
you're serving from your remote control PC. So you literally turn the
server on and off, fiddle with the BIOS and install the OS, all without
ever physically being in the same country.
Some day I may own a desktop computer which makes this server's dual
quad-core Xeons seem puny and pathetic. But it won't have reliability
and management features like a "server" does.
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Orchid XP v8 wrote:
> I think the "real" difference between a desktop and a server is probably
> fault-tolerance.
Yep. And when downtime starts costing you thousands of dollars per second,
you start doing things like having two independent entirely separate power
companies supplying the power to your building, along with several
independent ways of getting to your networks, including both satellite and
land lines, as well as several leased lines guaranteed not to be in physical
proximity and terminated in different states.
Now, maybe a large bomb in the building or an airliner crashing into it
would have taken it out, so they're probably behind the times compared to
(say) google, but it was pretty impressive for 20 years ago.
--
Darren New, San Diego CA, USA (PST)
Ada - the programming language trying to avoid
you literally shooting yourself in the foot.
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On Tue, 18 May 2010 22:10:15 +0100, Orchid XP v8 wrote:
> Even today, I see people selling "servers" which are really like
> "desktops". (1.2 GHz Intel Celeron with 512 MB RAM? I don't think so...)
Depends on what the server is doing. If it's just serving files up,
that's more than adequate; hell, I used to do file & print on an 80286
with 16 MB of memory.
Jim
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: 4bf2725b$1@news.povray.org...
> Does anybody know approximately when this time was?
I actually typed one single punch card in 1983 just before the machine was
sent to greener pastures. IIRC it was an Olivetti wih a red diode display
(no CRT) but I can't find the model right now.
In 1986 I worked in a lab where the punch card computer had just been
replaced by a mini-computer with CRTs (so there were stack of cards laying
around). The old tech guy who had been the punch card operator was being
retrained and had a hard time adapting to these new-fangled "monitors".
Before, when he was using the cards, launching a program consisted in
finding the right batch of cards, moving it *** very carefully *** to the
computer room (there were stories about him spilling programs on the floor)
, loading it in the computer and press a button. Now he had to use a regular
keyboard just like a secretary and type lists of foreign-looking commands
that didn't make any sense. He hated that.
G.
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Darren New <dne### [at] san rrcom> wrote:
> Clarence1898 wrote:
> > You can run Linux on an IBM z/series machine, just like on a PC.
>
> Actually, last I read, you could run some 300 Linux VMs on a z/series
> machine without noticing a slow-down. :-)
> --
> Darren New, San Diego CA, USA (PST)
> Ada - the programming language trying to avoid
> you literally shooting yourself in the foot.
I read an article in one of IBM's technical bulletins where they started running
more and more copies of z/Linux under z/VM. Somewhere past 10000 concurrently
running copies of z/Linux the machine finally cried enough. Depending on what
hardware you are running on, you could do that easily. That is unless you
started running Povray on all those copies.
Isaac
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