Path: utzoo!attcan!uunet!mcvax!hp4nl!kunivv1!wn2!janhen
From: janhen@wn2.sci.kun.nl (Jan Hendrikx)
Newsgroups: comp.sys.cbm
Subject: Re: SEQ file access speedup
Summary: All commodore drives do read-ahead
Keywords: Interleave, fast SEQ access
Message-ID: <335@wn2.sci.kun.nl>
Date: 16 Feb 89 15:00:48 GMT
References: <89Feb10.182100est.2732@godzilla.eecg.toronto.edu> <89Feb14.171816est.2394@godzilla.eecg.toronto.edu>
Organization: University of Nijmegen, The Netherlands.
Lines: 13

In article <89Feb14.171816est.2394@godzilla.eecg.toronto.edu>, leblanc@eecg.toronto.edu (Marcel LeBlanc) writes:
>                     That's because the dos in those drives only buffers a
> sector at a time, which forces it to use an interleave scheme.

That is not true. 1541 DOS does do read-ahead when there are enough
free buffers. When a new buffer is needed, and all are occupied,
one of the read-ahead buffers is discarded.

Source: Inside Commodore DOS, and a ROM disassembly.

> Marcel A. LeBlanc	  | University of Toronto -- Toronto, Canada

-Olaf Seibert