Question Recover Data from a non-standard HDD ?

Aug 17, 2022
I have an old Alps Hard drive that I want to try and recover the data. The problem is that there is only a 26-pin connector and no separate connector for power. The hard drive came out of a Yamaha C1/20 Music computer. I believe that the power was routed to hard drive differently than what is done today. I insert link to images of the hard drive. View:

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It appears to be a 20MB MFM or RLL drive ("020" in the model number is the capacity).

Here is the pinout of the 26-pin interface:

Pin 1 GND (20- 2)                       Pin 2 -Read Data (20-18)
Pin 3 GND (20- 4)                       Pin 4 -Write Data (20-14)
Pin 5 GND (20- 6)                       Pin 6 Reserved
Pin 7 -Drive Select/+Power Save (-)     Pin 8 -Ship Ready (-)
Pin 9 GND (20- 8)                       Pin 10 +Read/-Write control (34- 6)
Pin 11 -Motor On (-)                    Pin 12 Head Select(+Head 0/ - Head1) (34-14) 
Pin 13 -Direction In (34-34)            Pin 14 -Step (32-24)
Pin 15 -Write Fault (34-12)             Pin 16 -Seek Complete (34- 8)
Pin 17 -Servo Gate (-)                  Pin 18 -Index (34-20)
Pin 19 -Track 000 (34-10)               Pin 20 -Drive Ready (34-22)
Pin 21 GND (20-11)                      Pin 22 +5V (-)
Pin 23 GND (20-12)                      Pin 24 +5V (-)
Pin 25 GND (20-15)                      Pin 26 +12V (-)

The signals have the same name as the ST-412/ST-506 interface (between'()'), but the read/write signal is not differential.

This is the internal hard disk of a Toshiba T-3100. It uses a custom interface, probably similar to the ST-506 harddisk interface, but fewer pins. Both signals and power are combined in one 26 header.

Other machines using this type of hard disk interface:

  • Epson PX-16
  • Epson Equity LT
  • Epson Portable PC (Q150A)
  • Sharp PC-7200
  • Data General One Model 2T ?
  • GRiDCase 3 Plus
  • Toshiba T1200 ?
  • Wang WLTC Laptop
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What you have there is just a disk. All of the formatting and track information as well as locations of any bad or spare sectors are on the interface card. Essentially it is like having an IDE drive with the controller board removed (for IDE this controller was moved onto the drive itself, hence why it was called Integrated Drive Electronics).

As replacing this controller PCB with a different one often results in not being able to read the data unless you also transplant the NVRAM chip, it's probably best to send this one along with its controller card (I don't know if it's actually removable from your luggable PC) to data recovery experts. After all at only 20MB that's probably not that expensive.

If the controller is removable and can be installed in another 286 though I'd try that first
Aug 17, 2022
I believe that I will probably have someone professionally recover the data. I was hoping that I could find some type of adapter that I could just plug in and connect to a new SATA, etc.

Thank you.

I doubt that you will find any data recovery professional who can handle this drive. Do you still have any remnants of the Yamaha machine?

Maybe you could contact the owners of those online "computer museums" to see if they can help you? FWIW, I see some of those old laptops on eBay, but I don't know whether any have a compatible hard drive and/or controller.
Aug 17, 2022
I actually have the music computer that starts but the problem is that the monitor that is built into the computer is not working. The unit does have a CGA output, but I tried to use an adapter "D-sub HD15-Pin VGA To DB 9-Pin RGB Adapter Dongle " but it didn't work. I don't know if there is another method of connecting the CGA output to a VGA monitor.

Thank you.

CGA produces horizontal and vertical scan rates of 15.75kHz and 60Hz, respectively. Those are NTSC analogue TV frequencies. I suspect that your VGA monitor may not lock onto the lower horizontal frequency.

I think you need something like this which connects to the AV input of your TV:

Unfortunately you need to wire up the 9-pin CGA end, so you may want to keep looking until you find an alternative that is ready to go.