Wednesday, 30 January 2019

Memory Cubes, Cards and Holodisks.

Following my blog adding some depth to the subject of energy cells, I thought I might give a similar treatment to that of storage media.

Transhuman Space 3e p.141:
Portable data-storage units are teradisks (TDs). Each holds 10 TB and is the size of a sugar cube. $5, 0.01 lb. Old holodisks are still used on cheap machines (new systems can also run them): each holds 1 TB. $1, 0.01 lb.”

It is feasible that “disk” may become a generic term for storage media of any form. (I still promise to “tape” films for my girlfriend!) If you feel this may be confusing, alternate names for TDs include info-cube, memory cube, data cube, holocube, teracube, archive block, teradice, info-die, memory crystal, information crystal and so on. 

I am making the assumption that “size of a sugar cube” also implies that it is of a similar shape too. Incidentally, 0.01 lb is 4 grams, about the weight of a sugar cube. A cube is a space-efficient shape for a storage medium.
Sometimes it is impressive what you cannot find on the internet! A credible statement of the dimensions of a sugar cube proved elusive. The claim a sugar cube has a volume of 4.93 mls gives a cube of 17 mm sides, which seems on the large side. Not having any sugar cubes handy, I examined some dice of similar size and decided to make a memory cube 14 mm across. Like many dice, a memory cube may have rounded corners.

I am assuming the memory cube is a holographic storage medium, so is made of transparent material. It is possible an actual holographic media will just look like glass. For TS we might as well add some glamour and say its interior is iridescent with rainbow hues and some get used as ornamentation rather than their designed function. The surface of the cube can be engraved for identification. Readers automatically compensate for such legends or any other surface scratching.

There are a number of ways to read a cube. Many computers and similar devices have a reading deck, with a “glass” area on its upper surface. A cube is placed on a deck and the lasers and sensors beneath the glass read it. A basic deck has a “window” about an inch across. Better decks have a window of several inches and can simultaneously read more than one cube or card. Decks are also compatible with some other devices. More mobile computers have a small drawer into which one or more cubes are placed for reading. Such readers are preferred to decks in microgravity or weightless environments.

Memory Card.
One of the drawbacks of the memory cube is that it is a cube, making it too bulky for some applications. A memory card or “wafer” is a 12 mm x 1.2 mm square with rounded corners. The edge of the card is reeded to make it easier to handle. A card resembles a slice of memory cube, although its sides are actually a shade shorter.
Many designs of memory cube reader can also read memory cards. For a deck the card is simply placed on the reading surface. If a device lacks a cube reader compatible with cards it may have a dedicated card reader instead.
A memory card holds 0.85 terabytes (850 gigabytes) and costs $1.75. Price often varies with local availability and can be as low as $1 or higher than $3. It would be misleading to simply think of a memory card as the 2100 equivalent of a micro-SD card. A memory card can hold a lot of information in a very compact space, facilitating many other applications.

He held the tiny square of glass up between finger and thumb:
This is what you have been waiting for! Everything about the target. Floor plans, blueprints, personnel files, patrol schedules, everything!...there was a bit of space left, so I put some music and recipes on there too.”

Holodisks are an older format of storage media that is still widely used. It would be unusual to find a Fifth Wave household that does not have at least one holodisk player.
A holodisk resembles a modern CD or DVD disc, but is transparent. Like CDs and DVDs it must be spun for reading and has a 15 mm central hole for this purpose. Material intended for the developing world or less advanced regions is often placed on holodisk.
Two sizes of holodisk are commonly encountered. 120 mm diameter discs hold 1 TB of information and are the same size as an old CD. 80 mm diameter discs are handier for many applications and are correspondingly more common than other sizes. An 80 mm disc holds 0.42 TB/ 420 GB. Standard holodisk readers are designed for both 120 mm and 80 mm discs.
A holodisk reads from the centre outwards so any size less than 120 mm but usefully larger than the central hole is possible. 100 mm discs are sometimes encountered, and more rarely discs of 25-40 mm diameter. Non-standard sized discs may need to be placed in an adapter to be read by certain players. An adapter resembles a 120mm disc with central well of appropriate size.
Many holodisk readers are backwards compatible with non-holographic optical discs such as the various forms of CDs, DVDs and Blu-ray discs. This capability may be useful for historians and other researchers. Sadly many optical discs produced in the earlier decades of the century have exceeded their shelf-life and deteriorated with time.
Cheaper holodisk players, or those intended for specific purposes, may lack compatibility with optical discs. Pirated copies of players may claim compatibility but be variable in performance or non-functional for such discs.

Playable/Interactive Cards.
In some communities etiquette demands the exchange of physical business cards. Playable business cards are popular in such circles. A card can be played by placing it in a normal holodisk reader. Content is usually promotional material and web-links.
Since a holodisk needs to be transparent it has limited applications for business cards. Playable business cards instead use optical disc technology so they have can have a reflective side and a printed side. Cards may also use other storage mechanisms such as magnetic stripes, OCR characters, barcodes or QR codes. Hence they are sometimes referred to as “multi-media” cards. The optical storage capacity is a relatively modest 4 GB but this is adequate for the sort of content usually placed on cards. It is not possible to incorporate a memory wafer into a working playable card. 
Playable cards see other applications. A musical group might promote itself by handing out cards. Content would include sample tracks, videos, a calendar of future appearances and web-links. Cards are also used as coupons, for loyalty schemes, as hotel room keys and for some security passes.

Media Applications in 2100.
One thing to understand is that storage media are used less in 2100. If someone wants a book, film, music track, game or program they will download it directly from the web. Many people do this already, but by 2100 this will be the norm. Buying such items on a physical media would be unusual.

It is always prudent to have a back-up, however. Most Fourth or Fifth Wave citizens have at least one cube holding back-up copies of important or valued files. Cubes are readily available, reasonably priced, take up little space, immune to EMP and resilient against many other threats.

Residents in the more distant space colonies cannot access the internet as readily as citizens of Earth or Mars. They have to download from more local sources. Visiting space vessels often carry a few cubes with the latest InVids, slinkies and any other information updates a community might want. This can include anything from celebrity gossip to the latest research papers. A pound or so of update cubes can be a compact but highly lucrative cargo. It is not unknown for a packet vessel to be used solely as a transport for just a consignment of update cubes.

Cubes, cards and discs have to be read by a reader. Storage media not inserted into a device cannot be read remotely. The only information it broadcasts is its v-tag, if any. Information on storage media is therefore “air-gapped”, so cubes and other media are often used to store information that is too sensitive to leave on a machine that might be remotely accessed.

Similarly, cubes and other physical media are used to move information that one would not wish to transmit across the web.