D9090 & D9060 Hard Drive mechanism Change
The CBM DOS board, as seen in the photo below-left, is what controls the size & Format method for up to two hard drives connected to the SASI Controller.It is very easy to change the hard drive mechanism for any MFM drive. I have used Hard drives ranging in size from 6 meg up to 60 meg, and it makes no difference as the CBM controller will Format anything, as long as you tell it how many HEADS the Hard drive has. If you are not sure, try using a link on J13, then try the format command. If the error light comes on in less than 3 minutes, then remove the link from J13 and place it on J14.Try the format command, If the error light comes on in less than 3 minutes, then the drive is either faulty and you should throw it away, or the drive has an un-even number of heads and can't be used. (i.e.- 3 or 5 heads) The photo below-right shows the Jumpers J13 & J14. Remember J13 = 4 HEADS, Formats to 19,442 Blocks free. J14 = 6 HEADS, Formats to 29,162 Blocks free. Any BRAND Hard drive will work, such as SEAGATE, NEC, IBM, MINISCRIBE, CONNER, etc