Potentially a new idea for storing information in time itself and thus a new memory chip.

per bit electrical delay lines are bulkier than transistors.

sounds like "bubble memory" :)

something like that can be done using a scanning tunelling electron microscope (or something lik that) to manipulate individual atoms the main problem is miniaturisation :)

The best delay-line memory would be a few hundred kilometers of single-mode optical fiber. That could store gigabits, at great expense and absurdly slow access times.

John

I wonder if a terahertz radioation transceiver was used that could actually be a shorter length of fiber with high capacity and faster access times.

Isn't an flipflop a kind of 1bit delay line memory?

cheers, Jamie

To get 1 gigabit storage capacity, you would have to use DWDM. The delay in a 200 km long fiber is about 1 ms, thus, at 10 Gbit/s, the storage capacity is 10 Mbits or about the capacity of some old floppy disk.

Standard systems using 80 or 160 wavelengths multiplexed into a single fiber can store 0.8-1.6 Gbits.

Using only 100 km of fiber would cut down the attenuation sufficiently, so that optical erbium amplifiers (with have some wavelength limitations) are not required on the way. Without band limiting amplifiers in the system, a large wavelength range could be used with a larger number of wavelengths.

The average "rotational latency" would be 25 us and practically zero "track-to-track seek time" (between wavelengths). This would be a quite expensive, but fast 100-200 MB disk replacement for PCs :-).

I recall a video display terminal that stored the screen data (24 lines, 80 characters) in PMOS serial shift register memory. Nighmare.

John

Nope, not serial. Bog standard DRAM. YCLIU

higher

1. it has been done. 2. you can't go several hundred kilometers at a crack, there is too much attenuation. =20 Land based systems go 40 km, transoceanic cables have various amplifiers and regenerators along the way.

Attenuation in modern optical cables is far less than in electrical copper cables, leading to long-haul fiber connections with repeater distances of 70?150 kilometers (43?93 mi).

John

" To get 1 gigabit storage capacity, you would have to use DWDM. The delay in a 200 km long fiber is about 1 ms, thus, at 10 Gbit/s, the storage capacity is 10 Mbits or about the capacity of some old floppy disk.

Standard systems using 80 or 160 wavelengths multiplexed into a single fiber can store 0.8-1.6 Gbits.

Using only 100 km of fiber would cut down the attenuation sufficiently, so that optical erbium amplifiers (with have some wavelength limitations) are not required on the way. Without band limiting amplifiers in the system, a large wavelength range could be used with a larger number of wavelengths.

The average "rotational latency" would be 25 us and practically zero "track-to-track seek time" (between wavelengths). This would be a quite expensive, but fast 100-200 MB disk replacement for PCs :-). "

This reminds me of google which supposedly have their own fiber optic networks.

Perhaps they might be interested in using their optic networks as some kind of fast harddisk.

But if it would be 1 millisecond access time then they would probably not be interested in it.

That was the figure you mentioned I think...

Though you also mentioned 25 nanoseconds or so... not sure what that figure is about.

Would that be the access time for a single bit ?! ;)

I'm being a bit vague/lazy though... since it doesn't really concern me and is probably a whacky idea anyway ;) :)

But maybe "you hardware people" can make something lol ;) :)

Bye, Skybuck.

That doesn't sound like a very good delay-line memory, so how could it be the best delay-line memory?

If you want more massive storage, and are willing to put up with even more absurdly slow access times, I can think of a way to do it at a relatively small expense. Point a laser at a retroreflector on the Moon.

Of course, then there's the problem of where to put the data when the Moon is no longer overhead in your area...

John Savard

This has been done since 1969. There are small reflectors on the Apollo ALSEP packages an the laser beam is constantly used to measure the distance between the Earth and the Moon. Typically 1-2 m telescopes are needed both for the laser as well as for the receiver and all you get back is a few photons.

Thus, the data rate would be a few bits/second, thus the total storage capacity is a few bits.

To get some meaningful storage capacity, at lest 1 Gbit/s data rate would be required, With the largest (10 m) optical telescopes available _and_ with 100x laser power _and_ sending a new (football field size) reflector to the moon, this might be doable :-).

Here is another question for ya:

Suppose a living room is stacked full with fiber optics.

How many kilometers of wire would that be ?!?

Like micro-fiber-wire or something ! ;)

An estimation is ok ;)

Bye, Skybuck :)

According to windows live mail, your message kinda screwed up... it was an attachment ?!?

Was that deliberate or a gnu/linux mistake ? ;) :)

Bye, Skybuck :)