Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!uvm-gen!pegram
From: pegram@uvm-gen.UUCP (pegram r)
Newsgroups: comp.sys.atari.st
Subject: Re: High density Floppies on ST
Message-ID: <1348@uvm-gen.UUCP>
Date: 27 Nov 89 14:48:23 GMT
References: <3838@netmbx.UUCP>
Sender: nobody@uvm-gen.UUCP
Organization: EMBA Computer Facility, Univ. of Vermont, Burlington.
Lines: 31

From article <3838@netmbx.UUCP>, by hase@netmbx.UUCP (Hartmut Semken):

> Hmm, TOS will step at 6,12,2,3 msec (with rate codes 0,1,2,3).  
>Setting the controller to 6 msec and doubling the clock works for almost 
> all 3.5 inch HD drives.  
> >>It would also be hard to boot
from a floppy with this 
>>mod (double - 16Mhz - clock for 1772 + formatter + "6"msec seek rate).  
>>Do you have to have a seek rate setting boot sector on every boot 
>>floppy and would that idea even work?  
> > Sure, that should work, since no steps should be necessary to read the 
> boot sector.  
> I boot from harddisk...  
> > If the HD-floppy does not work after modifying the ST, the step pulse 
> width is a probable cause.  
> In that case, use an edge-triggered monoflop (1-shot?? RBP III)to "resize" 
> the pulse.
> hase 
> -- > Hartmut Semken, Lupsteiner Weg 67, 1000 Berlin 37 hase@netmbx.UUCP

Thanks for all the info, Abacus books bite the dust again. I'll get a
HD 3.5 floppy drive and let the net know how my '85 520 likes it.
Could you please post how - where to get your HD formatter, I'm sure
others would also like to know.  This is, after all, a real drive
upgrade and not that hard to do (wish Atari had thought of it, it's
also cheap - right up their alley).  I will be checking to make sure
that 1772s can generally handle the 16 Mhz clock.  Any more comments
anyone?  Sure hope that different formats are noticed automatically, as I
think they are.
thanks,
Bob Pegram (pegram@griffin.uvm-gen.uvm.edu)