Polesse #04 16 апреля 1999

Железо

We choose - Everything you wanted to know about floppy drives, but were afraid to ask.

                       WE CHOOSE ...



       Everything you wanted to know about floppy disk,

                      BUT were afraid to ask


(C) KVAZAR


                              "Floppy" - as many in this word

                               heart-user merged ...

                                         (Unpublished).


   When we hear the words: "floppy disk, floppy disk, a
We immediately before his eyes there is a familiar image of the 
black (sometimes white, red, green, yellow, etc.), square 
envelope with slots into which is placed and, in fact, the disc 
itself - round piece of flexible plastic, pokrytyy magnetic 
layer capable of storing various information, including our 
newspaper. 

   Everyone knows that the floppy disks - GMD (floppy disks or
floppy disk) are of two types: five inch 133 mm and three-inch -
92 mm. Not so long ago, there were eight-disk,
used in "large" computers, so-called "miniEVM. Now, like 
antiques can be found, except that on the roof of any 
craftsman, where they successfully fulfill the role of UHF TV 
antennas. Already today, three-inch floppy disk and three-inch 
drives, actively and universally displace five inch 
counterparts. Disadvantages past - are obvious: it's large size 
and low degree of protection of magnetic media from mechanical 
damage. 5'25 drives require two supply voltages, have a greater 
power consumption. All this leads to a reduction in the use of 
these drives and floppy disks and of course, sharply reduced 
the volume of their production. 

   Not spared such "Metamorphosis" and spektrumistov for which
five inch drives were originally "native". Due to the 
increasing shortage of such disks, an increasing number of 
users ZX-SPECTRUM forced to acquire the notorious "tripod" for 
which an upgrade is no longer a luxury but a vital necessity. 
Indeed, in Gomel for several months already 5'25 diskettes day 
the fire will not find, but for those that have wring these 
prices ... 

   3'5 floppy, though relatively expensive (1pc-$ 0.5), but 
without drawbacks of its cheaper predecessors, that more than 
compensated by material costs. So, today is one no surprise to 
the use of such disks and disk drives on SPECCY. 


   Five inch drives are usually at the top of the envelope 
brand identification sticker. On the import discs almost always 
specified, the manufacturer, but if such a label is missing, 
you should go to buy such a drive with caution. In addition to 
the label, except for manufacturer's logo, may be an indication 
of important technical information that can help make the right 
choice. 


   First of all, be aware that discs can be unilateral (no 
longer available) on the one working surface and bilateral - 
two. Currently, all floppy disks are bilateral, they have 
simultaneously (!) used the two sides with two heads in the 
drive. Accordingly, their capacity two times higher than 
unilateral. 

   The next parameter determines the amount of information 
placed on the disc is a recording density. Density is single, 
double and quadruple. Diskettes, calculated on double-density 
recording can be formatted as a single, but when trying to mark 
them on the quadruple density - may be errors.


   Imported double density drives are typically labeled
"2S/2D", which means "two parties" (Double Side) and "double
density "(Double Density). There are also other options for 
labeling disks of this type:" MD-2-D "," M2D "," MD-2/48 "," DS 
/ DD ". In the latter case, twice the recording density 
indicates the number of "48." The label of a floppy disk, this 
value may be, among other parameters: "48 Tpi" (48 tracks per 
inch). Disks quadrupled density, as a rule, are marked "DS / 
QD" (Quad Density), or "96 Tri" (96 tracks per inch). If found 
marking "2S/2D" combined with "96 Tpi", then drive the "double 
density", but it can be formatted as a "quadruple", without the 
risk of losing information. It is also found marked "96/100 
Tpi", similar to "96 Tri. Sometimes it means "high leaf-HD". 

   On the ZX-SPECTRUM may be freely used as disks
dual, and quad-density. Practical difference between them, the 
average capacity of 640 K: 2-sided, 80 tracks, 2544 sector. 
Some programs, such as DCU, RDS, FUT, allow format a floppy 
disk on a much larger number of tracks than Standard 80: from 
82 to 84, and on some "shovels" models drives even 87 (!). This 
makes it possible to obtain a sizeable adding capacity floppy 
disks. However, do not use this method, because First: these 
extra tracks often may not be readable on other drives, such as 
your friend whom you have brought such a disk with fresh toys

as Not all drives support the additional tracks,
and secondly: the readability of these tracks have always left 
much to be the best (usually the floppy read at the end is 
worse than in the early !!!). Therefore, use this format should 
be on the disks for use on one specific computer. 

   Stand out floppy disks, the so-called "high density",
widely used on PC-compatible machines (1.2 MB). Such
disks are labeled "HD" (High Density): "2S/HD", "MD-2-HD",
"MD-2/96". Distinctive features of these discs are
lack of internal O-ring in the hole for
spindle motor and the darker the magnetic layer. These diskettes
DO NOT WORK The vast majority of Spectrum DRIVE

                            !!!!!!!!

   This is due to the fact that their magnetic layer is made on 
dioxide chromium, which has a higher coercive force and 
requires a much larger current bias. To use such discs require 
special drives to 1.2 megabytes. 

   Currently, work is underway on the board, allowing read and 
write information to such a floppy with a high density up to 
1.44 megabytes in conventional disk drives 3'5 inches. 

   Beginners spektrumisty often commit serious
error using to protect the records in the five inch disks
Transparent labels - such as Scotch tape. Sensors on these 
optical drives, so you must use only non-transparent materials. 
In "treshechnyh" drives - all the way around. There are 
mechanical detectors. 


   Among the huge range of five inch floppy disk can be 
identified a dozen best-known product manufacturers and give 
their comparative evaluation. 


  Higher: BASF EXTRA, FIRST, DEXA, VERBATIM, KODAK, MAXELL, 3M

            (Teflon coated). Most preferably,

            although quite expensive. Have high stability
            completely parameters and high wear resistance.


  Good: BASF MEGA, POLAROID, 3M, SONY, TDK, BOEDER BIT-STAR,

            UNIMEX, NIPHA, KMT-130, Dialog, JVC, PHILIPS, RPS 
... 

            Somewhat worse than previous ones, but of 
sufficient quality 

            for use on any drive. Quite a mustache
            stably to wear.


  Average: MAXI-DATA, AMKETTE, MINI-DISK, TANDY, PRECISION, LG,

            IBM, KILOBYTES, MASTERDATA, CLAIME, TUNGSRAM, ENER
            GO-INFORMATICA, SIGMA. Drives the average quality of
            possess an increased number of dropouts. 
Depreciation             resistance is low. In the most 
"hackneyed" dis             ket at too intensive use, over


            time there is sloughing of the magnetic layer.


  Bad: COMP DISK, DISKETTE, Izotov, Electronics. Discs bad
            first quality with very low mechanical parameter
            mi. Usually do not have a lacquer coating and fast

            "Crumble". Due to the high abrasiveness at

            operation strongly "rustle", which leads to the 
first             Interim head wear drive. Some eq

            Legal Addresses prone to jamming inside the 
envelope. IP             use not recommended.