Date   : Sun, 20 May 1990 19:58:26 GMT
From   : mcsun!unido!balu!tilmann%cosmo.UUCP@uunet.uu.net (Tilmann Reh)
Subject: floppy drive hardware

Hello again.

Roger Ivie writes:
> Actually, the problem is in the drive rather than the controller. With
> 10 sectors per track the drive has to be within 1/2 percent of the spec
> rotational speed in order to reliably format a disk. DEC's RX50s (which

Well, he's quite near reality. But, after looking at the spec's of the 765
I found that 10x 512 Byte ARE POSSIBLE with rotational speed errors of 2 %,
fully within specs and with great enough gaps. BTW, 11 sectors are NOT
allowed.

But, as I mentioned in my last message, WHO DID EVER FORBID SECTOR SIZES
OTHER THAN 512 BYTE ???? Using 1k Sectors you get greater capacities, less
gap loss and a speed factor of TWO within sequential access. Why, I really
ask WHY DOES NOONE KNOW ABOUT THAT? Have a look at the Osborne's!

Last (not least), I have to mention that the 765 FDC is better than the WD
controllers. It does handle four drives without software overhead, and the
interfaces to both CPU and FDC are very simple. The software expense for
getting things working is smaller, as you don't have to fool around with
the bits on disk (when formatting, for example)...
BTW, did you ever hear of the 37 C 65 (from WD and SMC) ? It's fully compatible
to 765, but includes two clock osc, FDD decoder, 48 mA drivers and PLL.
It is just connected to FDD and CPU bus and works! Packaged in DIP 40
and PLCC 44 cases. I'm using it in my last project (a Z280 single europe card
computer) with great effort. Fine chip, better than every WD x79x !

Greetings, Tilmann