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New Mexico State University
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Department of Chemistry and Biochemistry


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 Everything About Floppy Disks!


FloppyThe drawing at the left shows the area where data storage surface of a 5 1/4" floppy disk can be contaminated. Never touch the magnetic surface and always keep the disk stored in a paper cover to keep dust away from the surface. If the disks are damaged they are easily replaced but a bad disk may destroy the writing ability of the disk drive. First a little back ground on floppy disks. Or skim the background but read the final paragraphs on the need for a 5 1/4" floppy to obtain quality NMR spectra from the Gemini 200 spectrometers.

Background -- Every computer must have some way of adding new software, saving data, (like a FID) and for general storing the computer's software. This is where "computer disk drives" come in. Disk drives are used to store data about anything. Therefore, when the computer is turned off, nothing is lost, and it can be retrieved when the computer is turned on. There are several different types of disk drives such as Floppy Disks (8", 5 1/4" or 3 1/2"),  Zip Floppy Disks, Hard Disk Drives, and CD-ROM drives.

Why are they called Floppy Disks?   A Floppy Disk is a thin piece of magnetic plastic surrounded by another piece of non-magnetic plastic. The floppy disk was invented some twenty years ago as a way of reliably storing computer data and information. Floppy disks require a "Floppy Disk Drive" to be written to, read from, or erased, but the actual floppy disk can be removed from the floppy disk drive at anytime. Since the floppy disk can be removed from the floppy disk drive, it can easily be used on multiple computers to share information between computers. Since the first floppy disks were so large (12" and 8" in diameter) and were so thin, they tended to sag or "flop" over when being handled. Therefore, they were named "floppy diskettes".

Modern Floppy Disks -- Through the years, because of their ease of use, floppy disks have been used on virtually every computer Floppy5made, and are still widely used today. Due to this popularity, manufacturers have continued to improve the floppy disk, and their drives. Today, floppy disks are far superior to floppy disks of the earlier days. For example, Floppy disks are now considerably smaller than older style disks (down to 3 1/2-inches wide). Modern floppy disks can now hold thousands of pages of typed information while floppy disks from those early years could only hold a few typed pages. Newer floppy disk drives can also read, write, erase considerably faster than those early disk drives.

The Five and 1/4-Inch Floppy -- When IBM developed floppy disks (and their disk drives) for use in their first Personal Computers they used a floppy disk that was 5 1/4-inches wide. This size has been popular ever since, but in recent years has lost popularity and is not even included on new computers. Sony developed a smaller disk that can also hold more information. It is called a 3 1/2-inch disk and is unlike other floppy disks because instead of a soft, flexible outer cover they use a hard plastic cover. The 3 1/2-inch disk is still considered a floppy disk, even though it is no longer flexable or "floppy".

Floppy Capacity -- Currently, floppy disk manufacturers still sell two different types of floppy disks, which hold different amounts of information. Every floppy disk has a certain "density", and that means how much data that floppy disk will hold. Just as, a 1-liter beaker will hold more water than a 0.5-liter beaker; a "High Density" floppy disk will hold more information than a "low density" floppy disk.

Gemini 200 Floppy Disks -- The capacity and format for the Gemini formatted disk is different from a floppy use by Windows or DOS applications. A Gemini floppy can be formatted only with the Gemini software and drive. The maximum storage capacity is at least 10 proton FID's or 5 carbon FID's on a single floppy. Used floppy disks should be put into the clear-plastic box beside the printer to be recycled.

Problem Floppy Disks --  If a floppy seems either not to store or allow data to be retrieved put a piece of paper with the floppy describing the problem and place it into the clear-plastic box beside the printer.

Precautions -- Gemini floppy disks are used by VHelper software to transfer Varian data first to a DOS system and then to a Windows environment for printing. The following is a list of precaution and suggestions for the use of 5 1/4" floppy disks.


Caution or Suggestion



 Keep floppy disks away from magnetic fields. Data will be erased


 Never touch the shinny magnetic surface of a floppy. May destroy Gemini Drive


 Keep floppy either in the drive or in a cover sleeve. Protect data surface


 Never force a floppy into the disk drive.  May destroy Gemini drive


Insert floppy into drive gently and close latch. Force may damage drive


Insert floppy into drive with label up with notch to your left. Data will not be recorded


Each floppy will hold ~10 normal size proton FID's. Use DCT(DSK5) to list files


Put filled floppy disks in the clear box next to the computer. Saves research time


Leave a message about a floppy that gives errors messages. Saves research time

Several Gemini commands can be used to show the content of a floppy. From the Gemini console simplest command is DCT plus the location of the files. In this case DCT(DSK5). The screen listing is in five column: Name, Type File, Length in kbytes, Starting Sector, and Length Sector.

Typical Result for 10 Proton FID's on a Single 5 1/4" Floppy

 File Name

Type (F=FID)

Length, kbyte

Start Sector

Length Sector

 S0001 F 22 4 102
 B2234 F 22 106 102
 SC196 F 31 208 140
 YA3211 F 31 348 140
 ZH0321 F 31 488 140
 JM0332 F 31 628 140
 VER341 F 22 768 140
 ACETON F 22 908 140
 FID1 F 22 1048 102
 Free  M   1150 129

The table above was obtained for FID's using the command DCT(DSK5) from the Gemini keyboard. Note that after storing 10 proton FID's there is still enough space for another FID. Carbon-13 FID's require about twice the disk space as a proton spectra; therefore, only 4 or 5 spectra can be saved to a single floppy. As a general rule never try to store more than 10 proton or 4 carbon 13 spectra on a single floppy.

The same command can be used in DOS with the following modification: DCT /b and the same data will be displayed. However, there will be two rows of five columns for two files. This method describes the size of the FID and shows how much free space is left on the floppy disk.

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