For a hard drive...
Laptop drives run off 5volt - same as the zip drive. All that's needed is an adapter that's commonly available (e-bay dealer shops usually have them & many computer parts stores do too). The adapter is need to combine the separate power and data cables for the zip connections to the single, more compact ribbon cable that carries both data and power to a laptop drive.
I've had a lot of experience changing drive types on the similar Roland VS840 recorder that was produced at the same time. There are issues which may be the same with the SP808....
The drive must have it's master/slave jumper set to master. Most laptop drives are set to master without a jumper fitted. Card readers usually do need the jumper.
Drive/media size is critical. The VS840 can only use 1GB. If the drive/card is around 4GB it can be used but only 1GB of it. Larger than 4GB won't be recognised at all. Some drives have a method of limiting their size to 2.1GB by fitting a jumper or any size you want if programmed on a computer which does the trick. I see someone has an 80GB drive working with an 808 - can it use all of that?
Using card media - you must shut the machine down before changing the card and only insert one with power off. The Zip drives disc eject command is not supported.
VS840 seemed to require EX software installed for anything other than a zip drive to be recognised.
Some multicard readers would not work - they may have complicated electronics that doesn't behave correctly for the machine. Simple readers for CompactFlash cards usually do work probably because this card type should already have an interface that acts the right kind of drive built into the card.
Some brand CF cards don't support the required drive emulation mode. Sandisk are usually a safe bet and I have some Kingston ones that work well too.
A company called Addonics made a Multi-card reader in the right (zip) sized box that did work with the VS840EX, but this is now discontinued. If it's been re-introduced or somewhere still has some - grab it! The 808 Nation one shown earlier looks remarkably like the Addonics.
Cimple Solutions are selling a CF reader in a drive case for use as a Zip replacement in Akai machines - it looks remarkably like the one I have in my VS840. The place I bought mine from no longer stocks them.
http://www.cimplespares.com/product.php/12058/0
Hope the above helps. Getting rid of the Zip drive makes a night&day difference to the VS-840 - in fact it brings it right up with anything else in it's class that's made now. No drive busy errors - fast and silent operation. Well worth doing. I can only hope it can work equally well for the SP808.
Cheers
Jim
I
Just when you think things couldn't get any more exciting - they don't.