8 Sep
2013
8 Sep
'13
3:33 p.m.
On 09/08/2013 11:34 AM, Tony Duell wrote:
So if the sector pulse is a few bit-times off, it
doesn't matter. The
controlelr will not see the 'right' number of 0's, but it doesn't count
them anyeway. I'll recgnise the '1' and start reading the header as normal.
Anent that, I once did a project that attempted to synthesize sector
pulses using soft-sector 5.25" media on old belt-driven drives (e.g.
Shugart SA400) that used very primitive speed controls. Since you had
only the index pulse to sync an entire rotation from, the speed
variations (particularly ISV) were entirely too large to do this
reliably. Direct-drive floppies (e.g. Teac FD55) were considerably
better, but a random sampling of various brands of 5.25" media pointed
up reliability to be less than ideal.
--Chuck