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Invisible wrote:
> I wonder... What's the bandwidth of a punch-card reader/writer?
Readers ran somewhere between 100 and 150 cards per minute, depending on how
much you paid for them. Roughly 80 bytes per card.
--
Darren New, San Diego CA, USA (PST)
Linux: Now bringing the quality and usability of
open source desktop apps to your personal electronics.
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On 1/05/2010 12:07 AM, Invisible wrote:
> I wonder... What's the bandwidth of a punch-card reader/writer?
Good question but I'm afraid I don't know off hand.
Suppose an 80 column card with 10 bits/column. That is 800 bits per
card. Maybe 20 cards per second through a reader ? Could be higher
since those things were really impressive bits of engineering.
Something like 16K bps ?
Now cards were not generally used for arbitrary data. For example in
many cases cols 73-80 were used for card sequence numbers. Data was
often characters so only 6 or 7 bits of variability for most characters.
Then the readers have to be fed.
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Paul Fuller wrote:
> Suppose an 80 column card with 10 bits/column. That is 800 bits per
> card.
No. If you punched all the holes out of the card (a so-called 'lace card'),
it wouldn't go thru the reader. It was 7 or 8 bits per column. Even binary
punched on the card was spread out so it wouldn't make too many holes.
> Maybe 20 cards per second through a reader ? Could be higher
> since those things were really impressive bits of engineering.
Some of them were very fast. Most were closer to 5 or 10, unless you had a
really high-end giant machine.
--
Darren New, San Diego CA, USA (PST)
Linux: Now bringing the quality and usability of
open source desktop apps to your personal electronics.
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>> Suppose an 80 column card with 10 bits/column. That is 800 bits per
>> card.
>
> No. If you punched all the holes out of the card (a so-called 'lace
> card'), it wouldn't go thru the reader. It was 7 or 8 bits per column.
> Even binary punched on the card was spread out so it wouldn't make too
> many holes.
>
>> Maybe 20 cards per second through a reader ? Could be higher since
>> those things were really impressive bits of engineering.
>
> Some of them were very fast. Most were closer to 5 or 10, unless you had
> a really high-end giant machine.
Ah, the wonders of the Internet. Ask any weird-arse question, and
*somebody* will know the answer! :-D
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Orchid XP v8 wrote:
> Ah, the wonders of the Internet. Ask any weird-arse question, and
> *somebody* will know the answer! :-D
Thinking on it, the difference was speed. Was it a mechanical card reader or
an optical card reader. Did it shine light thru the holes? Then you could
slide a stack of cards past pretty much as fast as you want, which was good
if you had a giant IBM or something and you wanted to do lots of processing.
Otherwise, it was cheaper to build a mechanical reader, with pins that would
complete circuits thru the holes in the card, which obviously meant moving
the cards slower. If your machine was sufficiently slow, there was no point
in having a faster card-reader. I only worked with the slow ones.
--
Darren New, San Diego CA, USA (PST)
Linux: Now bringing the quality and usability of
open source desktop apps to your personal electronics.
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> My employer's Internet connection is *guaranteed* to be 5 Mbit/sec in both
> directions at all times. (There are also contractual guarantees about how
> quickly the ISP will fix it if it breaks.)
>
>
> How much do you pay for your broadband?
Ouch!
IF you are lucky enough to dwell at a convenient location and get VDSL, then
you pay with t-com about 600 EUR/year for 25-50 Mbit/s downstream / 2.7-10
Mbit/s upstream, including a phone-flat and a few (for me) uninteresting
TV-programs.
If you want just 6Mbit/s - .5 Mbit/s and a phone-flat you pay about 468 EUR.
However, nobody here expands into rural areas. The reason is simple: if you
are in communications and invest into infrastructure, our laws force the
companies to "open" their lines to competitors at very cheap rates. So new
cables are only places below surface where they can be reasonably sure that
enough customers will stay with them to make it worth their while. That is
only the case where many people are crammed into very small spaces, like the
large cities. Free markets are not always good...
If you can only get ISDN (128 kbit) things get expensive - the worse the
line, the more you pay. Then you pay about 100 EUR/month (to my best
knowledge). Absurd.
In the worst locations here to get a 5 Mbit/5Mbit line you would have to
bundle 40 ISDN connections, so you would have to pay around 48.000 EUR /
year. Probably you could get this cheaper with other telcos.
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Darren New <dne### [at] san rrcom> wrote:
> Thinking on it, the difference was speed. Was it a mechanical card reader or
> an optical card reader. Did it shine light thru the holes? Then you could
> slide a stack of cards past pretty much as fast as you want, which was good
> if you had a giant IBM or something and you wanted to do lots of processing.
Wasn't that the idea with punched tape? (Although punched tapes might
actually predate punch cards...)
--
- Warp
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>> My employer's Internet connection is *guaranteed* to be 5 Mbit/sec in both
>> directions at all times. (There are also contractual guarantees about how
>> quickly the ISP will fix it if it breaks.)
>>
>>
>> How much do you pay for your broadband?
>
> Ouch!
Yeah, well, it's 5 Mbit/sec IN BOTH DIRECTIONS. (ADSL is typically 5
Mbit/sec up and 0.5 Mbit/sec down.) And it has service guarantees. And a
static IP address. Etc. In other words, it's a business package, not a
residential package. Hence the price tag.
> However, nobody here expands into rural areas. The reason is simple: if you
> are in communications and invest into infrastructure, our laws force the
> companies to "open" their lines to competitors at very cheap rates. So new
> cables are only places below surface where they can be reasonably sure that
> enough customers will stay with them to make it worth their while. That is
> only the case where many people are crammed into very small spaces, like the
> large cities. Free markets are not always good...
Laws forcing companies to do things doesn't sound like a very "free"
market to me...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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On Fri, 30 Apr 2010 21:37:55 +0100, Orchid XP v8 wrote:
> Laws forcing companies to do things doesn't sound like a very "free"
> market to me...
Free markets still need to be regulated so as to ensure they remain free
markets (ie, open to competition).
Jim
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Orchid XP v8 wrote:
> Laws forcing companies to do things doesn't sound like a very "free"
> market to me...
I don't know where TC is from, but we haven't had a free market in land-line
phone service in the USA in over 100 years.
--
Darren New, San Diego CA, USA (PST)
Linux: Now bringing the quality and usability of
open source desktop apps to your personal electronics.
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