On Thu, 14 Sep 2017, Warner Losh wrote:
Yea. It depends on the controller. WDC765 (or was that a clone of the NEC uP765)
I'm not sure if their legal people would like it being called a "clone", but it was definitely designed to be just like the NEC 765, instead of like WD's 179x
and the Intel 8287A
8272[A]. The 8287 was a bus driver/transceiver
and their ilk need these details since they try to cope with reading and they need some help guessing where the sector started. For some reason, the older WDC-179x chips didn't care, but on those chips to format a track you had to send it the sequence of bytes which would ultimately make it onto the drive (so there was no format track command, just a write track command).
But, the loss of a "read track" on the 765 took away some capabilites.
The speed improvement is quite noticeable. It was 2-3x faster with the interleave for a mostly sequential work loads, and the skew that venix did added about a 20% improvement on top of that. Random workloads sucked no matter what you did :(
There were also issues of how much processing the software tried to do between sectors. Different programs could get best advantage with different interlace and skew.
I have run into quite a few badly maintained drives. The innermost (higher numbered) tracks are the most sensitive to problems.
Yes. I had the most errors on those tracks when I was reading my big box of floppies back. My wife thought I was crazy for doing that... I'm not sure she was wrong :) As you might tell from this thread, floppies, reading them, and their formatting stir way too much passion in me (for which if it was too much I apologize)....
It dominated my life for a few decades. Wasn't that the MOST IMPORTANT aspect of microcomputers? -- Grumpy Ol' Fred ci...@xenosoft.com
