lester@suphys.physics.su.OZ.AU (K R Lester) (06/12/91)
As regards Mac drives, I am under the perhaps mistaken impression that the drives are nonstandard. I believe that apple actually changes the speed of rotation based on the position of the head from the axis of rotation, this allows them to keep the data desity roughtly constant i.e. store more on the outer tracks where the track circumference is longer. I suppose that it is possible to simulate this to some extent in software by changing the number of sectors per track according to the track number. This info may of course be wrong but Apple does have a long track record (no pun intended :-) ) of doing their own thing as far as disk drives (and computers, interfaces etc) are concerned Kim -- _______________________________________________________________________________ I lester@physics.su.oz.au I DOS - the original computer virus. Kim Lester: Dept. High Energy Physics, I Sydney University, I OS/2 on PS/2 - half an operating Down Under I system on half a computer. _______________________________________________________________________________
dhmyrdal@lise1.lise.unit.no (Dag H}kon Myrdal) (06/13/91)
I have the MAC/SE documentation here, and it appears that the HD drives are MFM (the same as Arch and MessyDos). However, old DD drives for Mac (and indeed when new MAC's access old discs) are accessed with diffeent speed per track inwards. So, one can have a standard HD drive for the Archimedes, but that will limit the reading of MAC discs to the new ones. As for HW: yes, the 177X controller found in the Archimedes can do HD. (But is it wired correctly for that - Acorn?) --Dag Haakon Myrdal ----------------------------------------------- about Norway: "Won an award, you know. Lovely crinkly edges" (Slartibartfast, THHGTTG)
panther@st1.vuw.ac.nz (06/13/91)
In article <1991Jun12.073638.16119@metro.ucc.su.OZ.AU>, lester@suphys.physics.su.OZ.AU (K R Lester) writes: > As regards Mac drives, I am under the perhaps mistaken impression that > the drives are nonstandard. I believe that apple actually changes the > speed of rotation based on the position of the head from the axis of > rotation, this allows them to keep the data desity roughtly constant > i.e. store more on the outer tracks where the track circumference is longer. Yep. S'right. Apple adopted this wanky system so as to squeeze more data on each disk than they could have otherwise, given the format that they used. The floppies are a royal pain in the neck. It makes them a totally non-standard system that is damn near impossible to work with as far as data transfers go. > > I suppose that it is possible to simulate this to some extent in software > by changing the number of sectors per track according to the track number. > I don't think so. A-MAX, an Apple Mac emulator on the Amiga, requires a Mac drive to be hooked up to read/write 'true blue' (or should that be 'True Rainbow') Mac disks. It can't emulate this in software. > This info may of course be wrong but Apple does have a long track record > (no pun intended :-) ) of doing their own thing as far as disk drives > (and computers, interfaces etc) are concerned Yeah, the company is a pain in the arse. 'How do we make people buy our machine exclusively ? Simple. We make it 100% incompatible with anything else they have on site!'. > > Kim > -- Rodger Donaldson "What the Hell we fightin' for, panther@st1.vuw.ac.nz Just surrender and it won't hurt at all #include <dis.claimer> Just got time to say your prayers, #include <dat.claimer> And then its time for the Hammer To Fall!" Phone +64 04 720-520 or --Queen, _Hammer to Fall_, from _The Works_ +64 067 24-431