At 11:29 μμ 17/4/2002, you wrote: >On 18/04/02 at 00:04 Dexter wrote: > > >> It is all explained in Keith Mitchell's hardware docs. Every other line > >> in the ribbon is an earth. By twisting lines 10 through 13 you are > >> swapping the drive 0 with the drive one signal with the earth line as a > >> pivot. Quite what the PC one does is not clear. > > >As I understand it, there are two drive select lines, allowing selection > >of one from 4 drives, so on a PC cable they flip those, and their grounds. > >Actually, originally the shugart standard (inherited from 8" drives) had 4 >drive selects and one motor on signal. When drives still had jumpers, you >could choose which one of the 4 selects to use, and wether drive select >also implies motor on, motor on is only alowed on a selected drive, or the >drive will turn on the motor when the motor on signal is active, regardless >of select signals. > >On the PC the drive was jumpered to use select 1. There are two motor on >and two drive select signals, but they are set to the actual 4 signal pins >of the standard, and actual selection has to be handled by twisting the >cable because that way the correct select and motor on appear where the >drive expects them.
Hmm so two drives can work simultaneously (theoretically?) Wouldn't that affect the data transmission?... IIRC there's no way to distinguish where the data is coming from on the Shugart I/F >These days drives do not have jumpers any more. there are two selects and >two motor on's, the correct combinatiopn is achieved using a twist in the >wire (the unused select and motor on end up on unused pins on the drive, >that once used to be select 2, 3, 4). So theoretically with the right twist you can access the drives even if they are prejumpered for DS1 right? (which brings me back to these IBM ED drives we talked about a while ago). BTW: Nasta as it getting a little late and I am kinda lazy (what else is new?) I am telling you here, that when you fix the QubIDE, send it directly to Dave so he can have it for his testing until he finishes the project. Mine is working fine now anyway (despite the little cable) so no problem - Unless you and Dave already covered that aspect. >The twist for miracle drives may actually be for SGC, so you can use the >right angle connector for drive 1 and 2 instead of 3 and 4. It worked the same with the Trump card IIRC... Phoebus
