Friday, July 15, 2011

Old Memory


Yes, I walked a mile through the snow to school. But, that really wasn't such a big deal (still isn't). I lived in a small town where walking was quite safe and there were sidewalks in front of almost every house.

But, in terms of computers, I started programming when the main input media was punched cards (I saved a lot of them for shopping lists for a number of years). When I started college, I worked on a "personal" computer that used punched tape along with toggle switches on the main processing unit. The main storage devices for the larger computers (IBM 360 at first, migrating to IBM 370s before I left) were huge disk drives.

However, memory (as mentioned before) can be categorized into temporary working memory and long-term storage memory. Working memory at that time was core memory -- little magnets that looked like donuts and linked together with copper wires. We still call it core memory after the memory of those days. Most working memory of today is now located within DIMMs (Dual In-line Memory Modules -- see Wikipedia) or, for older systems, SIMMs.

The memory modules have great advantages over old core -- speed, size, and capacity. They also generate much less heat which is both an energy savings as well as a design improvement.

Storage memory is another category which has moved from technology to technology. The first was paper (well, the VERY first was probably clay tablets or chiseled stone). For people, writing or drawing stored the data/information and reading brought it back. It's kind of funny, but efforts have been quite intense over the past twenty years to allow computers to do the same thing that humans have done -- to be able to directly make use of printed text and images.

For early computer systems, it was not possible for the computers to directly use text or drawings. They needed a way to detect a contrast between spaces. This usually meant holes. The holes allowed light, or a mechanical probe, to move through the paper. The areas without holes blocked the light or probe. In this way, the computer could read the "bits" (present/non-present, on/off, 1/0) and save it.

Next came magnetic methods. These were primarily on discs and tapes. The technology of disk drive design has developed enormously over the past 30 years such that a portable disk can hold the same data that a room of luggable, replaceable disks did way back when.

Currently, we are moving farther and farther along to making working memory cost-effective to use as storage memory -- which will lead to the next post on "New and future Memory".

Wednesday, June 8, 2011

The tree of data connectivity


The goal of data connectivity is to allow people to communicate with everyone else. The form of the connection may be voice, text, video, files, or some other type of data. However, the ideal is that it can transfer between any two (or more) people.

So, how does that happen? Well, the actual form of the data is in files that have some type of format. These formats, or organized forms, are standardized so that it can be created and transmitted, and then received and used. Examples of these are Adobe PDF files, Audio MP3 files, and Video MPEG-4 files. Voice is usually digitally encoded using one of the International Telecommunication Union (ITU) standardized formats such as G.711 or G.729.

Once a file has been created, it is transferred to the desired recipient. The current dominant types of transferring may be classified into wireless and landline. Wireless includes cellular data (and voice), Bluetooth, and Wi-Fi. Landline (using a physical medium for transfer such as a cable or fiberoptic line) makes use of many different protocols.

Wireless is the current popular option for the "end user" -- the person who is making use of the device that allows them to transfer data (remember that voice is just one form of data). However, wireless has significant restrictions. These restrictions are distance and/or speed. Companies are now marketing devices called "femtocells" (the actual brand and name of the device may not include this name) which are placed in homes or businesses to allow faster transmission by reducing the distance between the cell phone or Wi-Fi device and a landline.

Yes, a landline. Because of transmission requirements (which go beyond the scope of this current blog), it is just impossible to handle all of the data needs without going to a landline. A landline is self-contained for bandwidth (data capacity) while wireless must compete with all other wireless activity. So, landlines will (in my limited ability to read a crystal ball) always be needed and they form the trunks and branches of the tree of data connectivity with the wireless devices now being used as the leaves.

Biases and Prejudices: There is a difference

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