Connector - ST506/412Developed by Seagate. Also known as MFM or RLL since these are the encoding methodsused to store data. Seagate originally developed it to supporttheir ST506 (5 MB) and ST412 (10 MB) drives. The first drives used an encoding method called MFM (ModifiedFrequency Modulation). Later a new encoding method was developed,RLL (Run Length Limited). RLL had the advantage that it waspossible to store 50% more with it. But it required betterdrives. This is almost never an problem. Often called 2,7 RLLbecause the recording scheme involves patterns with no more than7 successive zeros and no less than two.34 PIN IDC MALE at the Controller. 20 PIN IDC MALE at the Controller. 34 PIN IDC FEMALE at the Harddisk. 20 PIN IDC FEMALE at the Harddisk.  | (at the harddisk) |  | (at the controller) |  | (at the harddisk) |  | (at the controller) |
Pin | Name | Description |
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2 | | Head Sel 8 | 4 | | Head Sel 4 | 6 | | Write Gate | 8 | | Seek Complete | 10 | | Track 0 | 12 | | Write Fault | 14 | | Head Sel 1 | 16 | RES | (reserved) | 18 | | Head Sel 2 | 20 | | Index | 22 | | Ready | 24 | | Step | 26 | | Drive Sel 1 | 28 | | Drive Sel 2 | 30 | | Drive Sel 3 | 32 | | Drive Sel 4 | 34 | | Direction In |
Note: All odd pins are GND, Ground. Data connector Pin | Name | Description | 1 | | Drive Selected | 2 | GND | Ground | 3 | RES | (reserved) | 4 | GND | Ground | 5 | RES | (reserved) | 6 | GND | Ground | 7 | RES | (reserved) | 8 | GND | Ground | 9 | RES | (reserved) | 10 | RES | (reserved) | 11 | GND | Ground | 12 | GND | Ground | 13 | | Write Data+ | 14 | | Write Data- | 15 | GND | Ground | 16 | GND | Ground | 17 | | Read Data+ | 18 | | Read Data- | 19 | GND | Ground | 20 | GND | Ground |
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