This is the Rodime RO652 hard disc inside the FileStore. It is a 20 megabyte hard drive when used on the Econet but I am not certain of the exact drive characteristics. I had a lot of trouble trying to format this disc until I used the proper Econet FileStore Formatting utility from Acorn.

The label on the top of the disc is the defect list which is blank, indicating a perfect drive at manufacture. Back in the 1980s when this Winchester disc was made, drives often had bad sectors when they were made. This would be listed on the drive so that they could be mapped out of the disc by the software running the drive. All the BBC micro Winchester drive formatters keep a defect list on the drive which can be updated by the user if new bad sectors emerge. Nowadays hard discs tend to be fairly reliable.

For some reason, which may be related to my mishap with the FileStore when I first got it, the drive does not power up properly if the FileStore is switched on alone. The drive light comes on and stays on but the controller does not mount the disc. For some time I thought that this meant the FileStore was broken. However, if you turn on the BBC or FileStore that the E20 is attached to, the drive comes to life. I presume that this means it waits for some sort of signal from the computer before doing anything.

I tried several of the hard disc formatters available whilst I had the E20 connected straight into a BBC Master. This was successful to an extent but the programmes always failed to read the "drive shape", ie. the number of cylinders and heads etc. so I had to skip this part of the formatter. They also tended to get stuck in a loop while verifying the disc, finding the same apparent error each time.

Using the FileStore as a local hard disc, I could format it in MFM mode (33 sectors per track) to give 20MB storage or RLL mode (47 sectors per track) to increase the space to 28MB. Using the official Acorn Econet FileStore Formatter, the disc is formatted at 62 sectors per track over 306 cylinders, giving the same storage space as 612 cylinders with 33 sectors per track which I thought it was in the first place!

I don't see any reason why the disc could not be formatted to a higher density for use on the Econet but I have no plans to re-format it at the moment. It would depend on whether the disc is an MFM or RLL type drive.

Although it cannot be seen above, the disc has a black panel which would form the front of a hard disc unit if this drive was not inside the FileStore packaging. There is a gap at the bottom right hand corner of the front panel for the drive light but this has been removed from the disc controller circuitry and replaced by two wires which attach to the drive light which fixes onto the front of the FileStore.

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