Disk Drive Data and Parameters
08/06/2001
Floppy Disk Drives
* Special Note: There were quite a number of different Floppy Disk-Drive Configurations, and as time went on there were a number of new Drive Manufacturers that entered the fray. Please understand that this list is not complete, by any means. It is presented here as only to show some of those initial concepts in those early days.
Some Descriptive Terms
Single-Sided (SS/density)Single-Density (sides/SD)Quad-Density (sides/QD) Extended-Density(sides/ED) Double-Sided (DS/density)Double-Density (sides/DD)High-Density (sides/HD) Grandiose-Density (sides/GD)
Date | Size | Model | Encoding Method | Type | Capacity | Tracks | Sectors per Track | Bytes per Sector | Mech'sm |
---|---|---|---|---|---|---|---|---|---|
Apr,'73 | 8" | SA801 | FM | SS/SD | 77 | 32/16/8 | 128 | Stepper | |
8" | SA801 | MFM/M2FM | SS/DD | 77 | 32/16/9 | 128 | Stepper | ||
8" | SA800 | FM | SS/SD | 262 Kb | 77 | 26 | 128 | Stepper | |
8" | SA800 | FM | SS/SD | 315Kb | 77 | 32 | 128 | Stepper | |
8" | SA800 | MFM/M2FM | SS/DD | 473Kb | 77 | 48 | 128 | Stepper | |
8" | SA800 | MFM/M2FM | SS/DD | 572Kb | 77 | 52 | 128 | Stepper | |
May,'79 | 8" | SA851 | MFM | SS/SD | 243Kb | 77 | 26 | 128 | Stepper |
8" | SA851 | MFM/M2FM | SS/SD | 486Kb | 77 | 52 | 128 | Stepper | |
8" | SA851 | MFM | DS/SD | 486 Kb | 77 | 26 | 128 | Stepper | |
8" | SA851 | MFM/M2FM | DS/DD | 972 Kb | 77 (2+75) | 52 | 128 | Stepper | |
8" | SA851 | MFM | SS/ED | 600 Kb | 77 | 8 | 1024 | Stepper | |
8" | SA851 | MFM/M2FM | DS/ED | 1200 Kb | 77 (2+75) | 8 | 1024 | Stepper | |
8" | SA851 | MFM/M2FM | SS/GD | 710Kb | 77 | 9 | 1024 | Stepper | |
8" | SA851 | MFM/M2FM | DS/GD | 1420Kb | 77 | 9 | 1024 | Stepper | |
8" | SA861 | MFM | DS/ED | 600 Kb | 77 | 8 | 1024 | Stepper | |
8" | SA861 | MFM/M2FM | DS/ED | 1200 Kb | 77 | 8 | 1024 | Stepper | |
Oct,'77 | 8" | PerSci 277 | FM | SS/SD | 243 Kb | 77 | 26 | 128 | Voice Coil |
8" | PerSci 277 | MFM | SS/DD | 800 Kb | 77 | 26 | 512 | Voice Coil | |
5.25" | SA400 | FM | SS/SD | 92 Kb | 40 | 18 | 128 | Stepper | |
5.25" | SA400 | MFM | SS/DD | Kb | 40 | 9 | 256 | Stepper | |
5.25" | T100 | FM | SS/SD | 180 Kb (172) | 40 | 9 | 256 | Stepper | |
5.25" | T100 | MFM | SS/SD | 340 Kb (344) | 40 | 17 | 256 | Stepper | |
5.25" | T100 | MFM | SS/SD | 400 Kb (404) | 40 | 5 | 1024 | Stepper | |
5.25" | Micropolis | FM | DS/SD | 180Kb (177) | 77 | 18 | 128 | Stepper | |
5.25" | Micropolis | FM | DS/SD | 180Kb (177) | 77 | 9 | 256 | Stepper | |
5.25" | Micropolis | MFM | SS/DD | 354Kb (335) | 77 | 17 | 256 | Stepper | |
5.25" | Micropolis | MFM | DS/DD | 800Kb (710) | 77 | 9 | 1024 | Stepper |
Date | Size | Model | Encoding Method | Type | Capacity | Tracks | Sectors per Track | Bytes per Sector | Mech'sm |
---|---|---|---|---|---|---|---|---|---|
Aug, '81 | 5.25" | MFM | SS/DD | 160Kb | 40 | 8 | 512 | Stepper | |
5.25" | MFM | SS/DD | 180Kb | 40 | 9 | 512 | Stepper | ||
5.25" | MFM | DS/DD | 320Kb | 40 | 8 | 512 | Stepper | ||
5.25" | MFM | DS/DD | 360Kb | 80 | 9 | 512 | Stepper | ||
5.25" | MFM | DS/QD | 720Kb | 80 | 15 | 512 | Stepper | ||
5.25" | MFM | DS/HD | 1.2Mb | 80 | 15 | 512 | Stepper | ||
3.5" | MFM | DS/DD | 720Kb | 80 | 9 | 512 | Stepper | ||
3.5." | MFM | DS/HD | 1.44Mb | 80 | 18 | 512 | Stepper |
Special Notes
- Most Drive Systems used "Soft-Sectors", where the number of Sectors per Track were determined by software/hardware controls.
- Some of the "Soft Sector" Drive Systems did not depend on a pre-punched "Index Hole" on the disk, but established a "Written Mark" as the beginning of the Sector.
- There were a few of those "Soft-Sectored" Drive Systems that had only one "Variable Sector" per Track on each track, that was altered in size as needed.
- There were a number of "Hard-Sectored" Drive Systems, where the number of Sectors per Track were pre-determined by pre-punched "Sector Holes" (32/16/8), along with the single "Index Hole".
- A term that was sometimes used in reference to taking a floppy disk and "Flipping" it over, as in a Single-Sided System, was to call them "Flippies". There were even some diskettes manufactured that had an additional hole punched in the jacket on the opposite side, to promote this.
- Technically, the so called "Single-Sided" diskettes were only certified for use on one side of the disk. Often, that was the only side that had been properly polished, but in lower quality Drive Systems they often proved to be still usable. Many folks improvised to save a few dollars.
- In those early days of 8" Disk-Drive Systems, you should be aware that those drives ran about $1,000 each, which made it rather difficult for the average person to put together that kind of system. Most of us made our own paper-tape and audio-cassette systems. A system that was quite successful for me was to use a modified audio-cassette drive that allowed what was called "NRZ" (Non-Return-to-Zero) data to be written or read from an ordinary tape, at bit rates between 3600 and 5600 bits per second, while most folks were using the 300Baud Tape Systems.
- Even when I put together my first 5.25" Floppy Disk Drive System, I thought I would never be able to fill up the 90Kb available on that Single-Sided Single-Density System! How things have changed.