On Fri, Jun 19, 2026 at 3:32 PM André Fachat <afachat_at_gmx.de> wrote: > > > > Am 19. Juni 2026 14:52:50 schrieb Francesco Messineo <francesco.messineo_at_gmail.com>: > >> On Fri, Jun 19, 2026 at 2:45 PM André Fachat <afachat_at_gmx.de> wrote: >>> >>> >>> >>> Correct. The only difference is that due to the smaller tracks the bits on the media get smaller two. Eventually reaching a point where the quality of the material (e.g granularity of the magnetic material) makes it unreliable. >>> >> >> it's not the material, it's the head's pole gap that are too large. >> 100 tpi heads (or 96 tpi ones, they're identical) have a much smaller >> magnetic gap. So with even higher clock rates, 8x50/SFD-1001 drives >> can format 29 to 23 sectors on the same magnetic media, and I've read >> without errors disks written in 1986 with the SFD-1001. > > > The gap may be smaller but not much. It's the bit frequency that matters for blocks per track, not the track density (tpi). of course, but 96/100 tpi drives need a smaller head that writes a narrower track, and as a side effect probably the gap is also smaller so CBM engineers decided they could also increase the clock rate by 3/2 (6 MHz vs 4 MHz clock, same dividers). The first 100 tpi drive ever made was the Micropolis 1015-II (single side) - 1016-II (double side). IZ8DWFReceived on 2026-06-19 15:01:12
Archive generated by hypermail 2.4.0.