Re: 1541 ROMs question

From: Nicolas Welte (
Date: 2001-12-18 12:21:50

Marko Mäkelä wrote:
> On Tue, 18 Dec 2001, William Levak wrote:
> > The 1541-II ROMs do not have the "save with replace" bug that all previous
> > ROMs had.  The 1541 is much more reliable with the 1541-II ROMs.
> Wasn't that bug corrected already in the 1541C ROM upgrade 251968-02?

It was, this ROM is very similar to the 1541-II ROM, except for the track 0
sensor code, of course. At least I said this in a posting that a Google
search turned up :-) But the 251968-02 is only seldomly found in any drives,
the only drive I know of that always had it is Joe Forster's 1541C, with an
Alps drive installed (and therefore without the track 0 sensor!). I was able
to buy the upgrade ROM (which actually is an EPROM), and this should also be
the copy that is on funet now. I never checked the checksum against the one
that is listed in the release notes, though.

The -03 ROM code is to be preferred for drives without the track 0 sensor,
but if you're lucky enough and have a 1541B/C with the sensor (it's only
found on some of the Newtronics drives) then the -02 should be used.
Personally I wouldn't bother to upgrade an old 1541, though. 1571s are much
better suited for any task that would rely on bug free operation of the
drive. And with the original ROM the 1541 can fulfil another task much
better: being 1541 compatible, for loading in old copy protected software :-)

Speaking of the 1571: Almost all drives I saw came with the buggy 310654-03
ROM version, and -05 was released in 1989 (the upgrade EPROM I have says so).
According to a posting by Fred Bowen in 1986 there was also a 310654-04
released. Does anyone have one of those? Ooops, they probably don't exist!
There seemed to be a problem in them, and they were stopped in the factory.
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