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From: fred@cbmvax.cbm.UUCP (Fred Bowen)
Newsgroups: net.micro.cbm
Subject: Re: C128 CP/M program "C1571"
Message-ID: <501@cbmvax.cbmvax.cbm.UUCP>
Date: Wed, 9-Jul-86 12:04:43 EDT
Article-I.D.: cbmvax.501
Posted: Wed Jul  9 12:04:43 1986
Date-Received: Thu, 10-Jul-86 04:57:54 EDT
References: <2592@caip.RUTGERS.EDU>
Organization: Commodore Technology, West Chester, PA
Lines: 36

> From: prindle@NADC
> 
> One very popular, and very handy, CP/M utility for the 128 is Von Ertwine's
> "C1571", which promises and delivers accelerated writes to 1571 disk files by
> eliminating a redundant verify done by the CP/M BIOS after each disk sector
> write (redundant in the sense that the 1571 already is doing an internal
> verify anyway).  Consequently, I was tempted to execute this in my PROFILE.SUB
> at boot up.

Partly correct.  The BIOS does not perform any verifies- it is (and always
has been) the 1571's job to do this.  The speed-up comes from the elimination of
most of the drive's retrys-on-error.  C1571 does not alter the BIOS.

> However, I just noticed an undesirable, and somewhat unexplainable, side effect
> of this program: once it has been run against a drive, that drive will no longer
> read MFM formatted diskettes (well, I tried IBM, OSBORNE, and KAYPRO IV, and 
> they all failed).  The system just hangs after a sector or two have been read,
> and the keyboard scan stops (no more keyclicks); a reboot is necessary.  I hope
> this can be fixed and the program will be re-issued along with the "new-new-new"
> CP/M 3.0 release which has been announced.
> 
> Frank Prindle
> Prindle@NADC.arpa

The first releases of C1571 were a kludge that did eclipse CP/M's MFM
capability.  The culprit was a bit of 'patch' code that was placed over the
MFM wedges in the 1571 DOS-  undesirable indeed.  The latest releases have
in fact corrected this.  Versions of this updated utility are available via
Compuserve.  I am trying to confirm that the latest version is also on the
current CP/M release (who knows what all falls through the cracks these days!).
-- 
Fred Bowen			uucp:	{ihnp4|seismo|caip}!cbmvax!fred
				arpa:	cbmvax!fred@seismo.CSS.GOV
				tele:	215 431-9100

Commodore Electronics, Ltd.,  1200 Wilson Drive,  West Chester,  PA,  19380