From owner-freebsd-hackers Fri Sep 8 09:21:53 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id JAA14804 for hackers-outgoing; Fri, 8 Sep 1995 09:21:53 -0700 Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id JAA14753 for ; Fri, 8 Sep 1995 09:21:13 -0700 Received: from sax.sax.de by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id SAA15126 for ; Fri, 8 Sep 1995 18:21:09 +0200 Received: by sax.sax.de (8.6.11/8.6.12-s1) with UUCP id SAA01234 for freebsd-hackers@freebsd.org; Fri, 8 Sep 1995 18:21:08 +0200 Received: (from j@localhost) by uriah.heep.sax.de (8.6.12/8.6.9) id PAA13198 for freebsd-hackers@freebsd.org; Fri, 8 Sep 1995 15:13:07 +0200 From: J Wunsch Message-Id: <199509081313.PAA13198@uriah.heep.sax.de> Subject: Re: higher density diskettes To: freebsd-hackers@freebsd.org (FreeBSD hackers) Date: Fri, 8 Sep 1995 15:13:07 +0200 (MET DST) Reply-To: freebsd-hackers@freebsd.org (FreeBSD hackers) In-Reply-To: <199509081007.UAA09665@godzilla.zeta.org.au> from "Bruce Evans" at Sep 8, 95 08:07:08 pm X-Phone: +49-351-2012 669 X-Mailer: ELM [version 2.4 PL23] MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Content-Length: 1209 Sender: hackers-owner@freebsd.org Precedence: bulk As Bruce Evans wrote: > > >Can the 765 read 'raw' tracks, as well as pick sectors out of them? > > Yes. It can do essentially everything that a WD-style floppy controller > can do except write raw tracks. Yno. Sort-of. Reading an entire track will only synchronize on the ID field of the very first sector on the track. You have to perform *bit-level* synchronisation for all subsequent sectors yourself. This is nothing one would like to do except for debugging purposes. I've done it once when writing my CP/M floppy BIOS. Anyway, any caller is free to request any sector with any length from the 765 (as long as he knows how long the sector will be before actually starting the operation -- or he will have to make two passes, one to read all sector IDs and a second one to actually read them). Except, the BIOS doesn't support such weird schemes. See my other reply on OS/2's XDR format for an example of what can be done. Needless to say that currently, FreeBSD is one of the last operating systems that could be installed off a plain 1.2 MB drive. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ Never trust an operating system you don't have sources for. ;-)