Looking for a ST419

M H Stein dm561 at torfree.net
Fri Oct 31 11:43:02 CDT 2008

-----------Original Message:
Date: Fri, 31 Oct 2008 00:48:21 -0700
From: "Chuck Guzis" <cclist at sydex.com>
Subject: Re: Looking for a ST419

On 30 Oct 2008 at 10:45, Chris Elmquist wrote:

> I realize that the operating system had individual sector write-ability
> but was that accomplished by read-modify-write of that individual sector
> in a controller buffer and then the entire track rewritten?  or did the
> controller sync to the beginning of the specific sector and write it
> in place?

Just that way--like a floppy--there are address marks and sector 
headers that mark the beginning of each sector. At least that's the 
way most controllers work.  Of course, since the data stream from an 
ST412 interface is just a raw bunch of pulses, one could record 
anything on a track that one wanted, within the electrical limits of 
the drive.



The Cromemco STDC ST506-type controllers are an example of a controller
that *did* format/read/write entire 10K tracks (no physical sectors), with a
four-track cache.


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