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With the winter finally behind us, it is time to put that winter bedding away for yet another year. While flannel sheets and heavy comforters are perfect for those cold winter nights, most of us look forward to sleeping under light cotton sheets and lightweight throws. With a little care and preparation, your winter bedding will be as fresh as a spring morning the next time you bring it out.

Be sure to give your winter bedding a proper cleaning before you put it away. While going to the laundromat is not the ideal way to spend an afternoon, it will save you loads of time when washing your winter bedding. Use one of the large-capacity washers to launder your blankets and comforters. If you have a good quality duvet, you may want to have it dry-cleaned to ensure that it is not damaged.

If you do decide to wash your duvet while you are at the laundromat, be sure to pay careful attention to the washing instructions. It would be an awful shame to ruin your expensive down duvet by ignoring the washing instructions. Contrary to popular ideas, a down duvet can be washed in a washing machine. Just be sure to use a mild detergent, and throw a couple of tennis balls in the dryer with it. This will help distribute the down as it is being dried.

Be sure to use a mild detergent to preserve and extend the life of your bedding. As you are most likely aware, white sheets ought to be laundered separately. To keep your whites as white as can be, be sure to use oxygenated bleach. Chlorine bleach can be extremely harsh, and it tends to leave a residue that can be damaging to the material.

Flannel bedding ought to be washed and dried separately from your other bedding. Flannel sheets tend to leave a lot of lint in the dryer, and it can cause a real mess if you mix them with your other bedding. In our experience, we have found that the best way to dry flannel sheets is to hang them outside to air dry. This will help keep your bedding in good shape and ensure that you can enjoy them for many winters to come.

Katie Curtis is a business consultant who spends a lot of time on the road. When she is not trying to solve other people’s problems, she fantasizes about getting a good night’s sleep. In her spare time, she writes for thebeddingsite.com - a wonderful website with extensive information on specialty pillows, children’s bedding, bed accessories and more.

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MAGNETIC DISK STORAGE

Magnetic disks used a similar recording system to the drums, but arranged on magnetic coated platters, made of aluminum, approximately 1ft in diameter. Initially fixed in a stack in a cabinet, the disks later came as a removable ‘pack’ of 6 platters. These packs could be ‘mounted’ vertically (spin horizontally) on a drive, as required, and then replaced with another to suit operating requirements.

Read write heads contained in the drive were aligned to move in towards the center of the disks,or and addressed data on both surfaces of the platters (though not the topmost or lowermost surface). A ‘Track’ is the circular path of one head on one platter. A ‘Cylinder’ refers to addressing the same track on each platter in the disk pack, forming an imaginary cylinder. The drives spun at speeds in the hundreds of RPM range. The heads were driven by hydraulics, step motor, or voice coil, and had either a servo system or a servo track for address location. The time taken to get the heads on track is the ’seek time’. Capacities ranged from 10 to 100MB as development improved. Much time was spent aligning the heads on track, and recovering from crashes!

The HDA

The next development was the HDA, or Head and Disk Assembly. Essentially similar to the ‘disk pack’, but fixed in the drive cabinet, the HDA came as a sealed unit with heads ready aligned in the factory, the disks unable to be accessed by the operator (or engineer). The read/write heads were controlled by a voice call mounted in the drive.

The idea was to improve the performance by ‘eliminating’ the entry of dust to the HDA. Improved capacity was achieved by allowing finer tolerances to be set in the assembly plant. Capacities were improved over the range of 100 to 600MB.

Although there was a big improvement in reliability, there was still deterioration in the magnetic surface. A technique known as ‘Bad-Spotting’, first developed to extend the life of drums, could be used by the engineer to specify a location on the disk surface which had become unreliable. The failing address or area would have been identified by monitoring the system fault logs, showing addresses which had to be re-attempted.

Bad-Spotting made use of ’spare’ areas on the same track as the faulty area. A special type of read would identify the area, and the entire track after this ‘bad-spot’ would be shifted, so that the bad area was skipped. Alternatively, if no spare area was available, a separate track, specifically reserved for this purpose would be used to relocate this address.

A bad spot table kept a record of all relocated addresses. Following this exercise the disk had to be re-initialised or formatted to use the new physical locations.

Eventually the disk surface would deteriorate to such an extent, or a head crash would occur, requiring the HDA to be replaced.

The PC

The advent of the PC and the requirement for small parts accelerated the development of smaller disks. When the pc disk capacities entered the 100MB and up range, they became viable alternatives to the large HDAs. These drives resembled a miniature version of the disk drive cabinet. They had a stack of several platters and heads arranged on arms. The stepper motors used a worm drive arrangement to locate the correct track.

A cabinet of PC style disk drives might contain several banks of 8 drives to a bank, giving better total capacity than the HDA, and possibilities of redundancy within the cabinet(see below). Also air conditioning requirements were relaxed, and a smaller footprint (space taken by the cabinet) was possible. As disk drives improved they were incorporated into the cabinets in ever increasing capacity.

Redundancy became possible relatively cheaply with the lower cost of drives. The principle is to write identical data to two drives for each address, so that, if one drive fails, the other can be used. A sophisticated version would switch in a spare drive to take over from the defective one, allowing the faulty drive to be replaced, while the user continues on without interruption.

The RAID system (Redundant Array of Independent Devices) is a refinement of this technique. Redundancy can be had in pairs of drives, as above, or in stripes across a series of drives, or a combination of both.

In part 3 we look at magnetic tapes.

Tony is an experienced computer engineer. He is currently webmaster and contributor to http://www.what-why-wisdom.com. A set of diagrams accompanying these articles may be seen at http://www.what-why-wisdom.com/history-of-the-computer-0.html. RSS feed also available - use http://www.what-why-wisdom.com/Educational.xml

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Good management of food storage areas is of paramount importance for the prevention of food contamination. Here is a rundown of my ten principles of correct food storage.

Wash out and defrost your fridge at least three times a week. Clean up spillages immediately.

Keep all cupboards, pantries and larders spotlessly clean.

Check regularly for signs of mice, rats, cats, birds, cockroaches, ants and such pests. Deal with them promptly. In professional kitchens, shelving should never be against the wall. Leave a space of thirty centimeters so that you can easily see trails of mice or rats.

Do not keep highly perishable foodstuffs in the larder, put them in the fridge. E.G. Eggs, milk, cheese, meats. Store prepared food separate from uncooked food.

Keep all cleaning chemicals and equipment out of food storage spaces. Put them in a special cupboard under lock and key.

Food storage spaces should be designed to stand against interior walls only. This will serve to ensure that these places will always be cool and dry.

Do not run water or drainage pipes through places where food or food utensils are stored. Keep your stores dry.

Be sure to rotate your supplies thoroughly. Remember this saying; “last in, last out”.

Keep animal feed separate from human food!

Keep vegetables and eggs in a separate storage area but failing that keep all root vegitables at the very bottom of the fridge in suitable closed containers. (special storage solutions can be found on the market that allow the vegetables to breath).

I’m Andy Routledge and I write articles and copy. I just love to write and will take on any challenge. My articles are all written with a deep respect for the written word and a sense of fulfillment in doing a job that’s really worth doing. If you would like to contact me please do so by e-mail at andrew@routledge associates.com or you can leave me a voice mail at aky292b@gmail.com.

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