Differences between version 4 and previous revision of MFM.
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| Newer page: | version 4 | Last edited on Saturday, September 20, 2003 9:43:57 pm | by JamieCurtis | Revert |
| Older page: | version 3 | Last edited on Saturday, September 20, 2003 9:42:56 pm | by JamieCurtis | Revert |
@@ -4,29 +4,23 @@
This interface predates [IDE], and is not used anymore for harddrives. It was developed in the 1980's by [Seagate].
Typical harddrive sizes are 5MB, 10MB and 20MB.
-[MFM] actually refers to the encoding method used for storing data on the disk.
-%%%
-Another encoding method used with this interface is [RLL].%%%
-
+[MFM] actually refers to the encoding method used for storing data on the disk. [MFM] is an acronym for "Modified Frequency Modulation".
+Another encoding method used with this interface is [RLL]. ([RLL] encoding is possibly still used on modern [IDE] drives)
-ST-506/ST-412 cables look like skinny [IDE] cables. (About half the width?)
-
+ST-506/ST-412 cables look like skinny [IDE] cables. (About half the width?)
A single ST-506/ST-412 harddrive needs two cables, one is 20 pins, the other is 34 pins.
The biggest problem with this interface[1] is that there is no logic board mounted on the harddrive. The harddrive is controlled
-by a separate controller card. Each harddrive requires its own unique controller card. Don't expect the controller cards to have any markings on them to indicate which harddrives they belong to/can work with.%%%
-[
ST-506/ST-412]
harddrive but no controller card?%%%
-.%%%
+by a separate controller card. Each harddrive requires its own unique controller card. Don't expect the controller cards to have any markings on them to indicate which harddrives they belong to/can work with.
You have an ST-506/ST-412 harddrive but no controller card?
Bad luck, use it as a boatanchor or a doorstop
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Apparently floppy drives still use this protocol (with [MFM] encoding)
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-ST-506/ST412 hardrives are BIG, NOISY, HEAVY and UNRELIABLE[2]. (About the size of a CD-ROM drive)%%%
-(
They sound like typewriters IIRC :)
+ST-506/ST412 hardrives are BIG, NOISY, HEAVY and UNRELIABLE[2]. (About the size of a CD-ROM drive.
They sound like typewriters IIRC :)
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''"The last time I fiddled with an [MFM] harddrive was about 15 years ago, so most of this is from memory and whatever I could quickly google up ;^)" -- [MarcelVanDeSteeg]''
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[1] Besides the slow speed and the small storage capacity of the harddrives :D
[2] I ran into a working example the other day, buried in the internals of an old 4Mhz 8088 XT.
CategoryHardware
