On Mon, Jul 17, 2023, 3:34 PM Chuck Guzis via cctalk <cctalk@classiccmp.org>
wrote:
> On 7/17/23 11:53, Ethan Dicks via cctalk wrote:
>
> > Chuck Dickman's algorithm is in lbn2rx50.c
> >
> > #define RX50_TRACKS 80
> > #define RX50_SECTORS 10
> >
> > int interleave[] = { 0, 2, 4, 6, 8, 1, 3, 5, 7, 9 };
> >
> > track = lbn/RX50_SECTORS;
> > track = (track + 1)%RX50_TRACKS;
> >
> > sector = lbn%RX50_SECTORS;
> > sector = (interleave[sector] + 2*(track - 1) +
> RX50_SECTORS)%RX50_SECTORS;
>
> Depends on the application. Files-11 RX50 encoding is a bit stranger,
> with Track 79 mapped to physical track 0.
>
> I can pass my algorithm along, if anyone is interested.
>
> On the other hand, DECMate II and Rainbow use sector interleave but not
> track skew.
>
> If anything can be said about DEC, they were consistent in their
> inconsistency.
>
Yup. The Rainbow's track 0 and 1 were not interleaved to make the boot
loader easier... I think the decmate did yhe same but with different
tracks...
The rainbow also had a cool partitioning format that looked like it was
some general thing, but I never saw it elsewhere or have found an
electronic copy of the printed docs I pulled off dec's tops20 support
machine from the LSG in the late 80s
Warner
--Chuck
>
>
>
>
