Scor­pio News

  

January–March 1987, Volume 1, Issue 1











Page 40 of 63











A Beginners’ Guide to 1/2" Magnetic Tapes by Timectaim

(2d. = Ae well ae using thete Lranefercing filer between many different disk sizes number of usert are also using them for transferring Sagnecic topes. this article dean extract from the manual for Tis Bagnetic tape aub-aystem for the M-F-B and describes some of the besice of 1/2" Tapes. Our thanks to Timeclaim for allowing us to reproduce this documentation, which is copycight (e) TH

Introduction plastic reels ie round the ed ther 300’ of 600” of ) or 12’ (holding 2400” of cape). The centr f so that they ali fit the same tape drives. (Ulstory will reveal some exceptions Bue these ave almost never seen today).

tape comes rip of pl

Tapee are said to have 9 tracks because the recording head consists of 9 tections one above the other. All tracke ar@ recorded at the same time unlike tape cartridges vbich usually are recorded one track at # time, There are some old’ 7 track tape machines about but theve are rarely encountered.

Density eed

ant that the density of data recorded on tape has been incri in nowads ae follows

800 bpL NRZT (Non Return to Zero Inverted) 1600 bpi PE (Phase Encoded)

3200 dpe PE

6250 bpi GCR (Group Coded Recording)

The density refers to the number of bite per inch on each track. complete byte is written at a time (with the 9 head sections) the num veer per inch is equal to the number of bits per inch. In the above table it

11 be seen that there are some further letters. These describe the method by which data is recorded on the tape. This Information really needs to be KNOW. only dy the tape deck engineece

800 bpi tape are almost obsolece in the data processing world vhere there is # Reed to store a great deal of data on a tape. However, many CAD/Engineering/Scientific users still use G00 dpi as they do not wauaily need to atore so much data Often they will only use the First few feet of tape one 7 eel

1600 bpi has become the data exch: write at 1600 dpi so this ta how dat another.

3200 bpi. TI a double density version of 1600 bpi. This density te Usually quite a cheap add on for 1600 bp! tape decks but if almost never used for data interchange.” Systeme using this are fairly unucual.

ndard. Most tape decks can read and ie usually transported from one aysten to

6250 bpi. This Le the Latest development in 1/2" open reel tape and is coming into uge at many mainframe computer sites. Most 6230 bpl drives will als

and veite at 1600 dpi. 6250 bpi drives are much more expensive than 1600 Dpi and are ‘not available in sone countries,

out on written onto tape in one complete 8 bit byte rity bie which 1e dealt with autom

The 9th track a ibaot seen by er ince «block

tres Encoded cep ay Length Sut blocks shorter than it to ls byces are not eiiowed, the actual ainiaua


This is an OCR’d version of the scanned page and likely contains recognition errors.











Page 40 of 63