IBM Type 1

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'''IBM Type 1''' (33FD) is a type of 8" floppy disk used by IBM. It uses [[FM encoding]] at a track density of 48 tracks per inch and a bit density of 3,268 bits per inch, on single-sided single-density media. There are three subtypes, with different sector layouts and slightly different total storage capacity.
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'''IBM Type 1''' is a type of 8" floppy disk used by IBM for the 33FD drive used in the 1970s and 1980s on some mainframes and minicomputers such as the 370 and System/34. It uses [[FM encoding]] at a track density of 48 tracks per inch and a bit density of 3,268 bits per inch, on single-sided single-density media. There are three subtypes, with different sector layouts and slightly different total storage capacity.
  
 
== 242 KB ==
 
== 242 KB ==
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This format has an index cylinder of 26 128 byte sectors, and 74 regular data cylinders of 8 sectors of 512 bytes each, totalling 592 data sectors with a capacity of 303,104 bytes.
 
This format has an index cylinder of 26 128 byte sectors, and 74 regular data cylinders of 8 sectors of 512 bytes each, totalling 592 data sectors with a capacity of 303,104 bytes.
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== Links ==
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* [https://www.computerhistory.org/collections/catalog/102673001 Computer History Museum: 33FD drive]
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* [http://www.bitsavers.org/pdf/ibm/system34/fe/SY31-0457-5_System_34_5340_System_Unit_Maintenance_Manual_Jan81.pdf IBM System/34 5340 System Unit Maintenance Manual]
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* [https://books.google.com/books?id=MFGj_PT_clIC&pg=PA515&lpg=PA515&dq=ibm+33fd&source=bl&ots=ZIjmZ7s7bI&sig=ACfU3U3G3B8qsnQ05KbcUiKH7Lw1VVqc3A&hl=en&sa=X&ved=2ahUKEwj60_vVm7LkAhUCrlkKHZDwB-EQ6AEwFHoECAkQAQ#v=onepage&q=ibm%2033fd&f=false Some references to the drive in a book on IBM 360 and 370 systems]
  
 
[[Category:IBM]]
 
[[Category:IBM]]

Latest revision as of 14:42, 2 September 2019

File Format
Name IBM Type 1
Ontology
Released 1973

IBM Type 1 is a type of 8" floppy disk used by IBM for the 33FD drive used in the 1970s and 1980s on some mainframes and minicomputers such as the 370 and System/34. It uses FM encoding at a track density of 48 tracks per inch and a bit density of 3,268 bits per inch, on single-sided single-density media. There are three subtypes, with different sector layouts and slightly different total storage capacity.

Contents

[edit] 242 KB

This format has 73 tracks (cylinders) with 26 sectors storing 128 bytes each, for a total of 1,898 sectors holding 242,944 bytes.

[edit] 284 KB

This format has an index cylinder of 26 128 byte sectors, and 74 regular data cylinders of 15 sectors of 256 bytes each, totalling 1,110 data sectors with a capacity of 284,160 bytes.

[edit] 303 KB

This format has an index cylinder of 26 128 byte sectors, and 74 regular data cylinders of 8 sectors of 512 bytes each, totalling 592 data sectors with a capacity of 303,104 bytes.

[edit] Links

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