Re: My finding about the 90x0 ROMs

From: Ethan Dicks <>
Date: Fri, 11 Feb 2011 13:34:39 -0500
Message-ID: <>
On Fri, Feb 11, 2011 at 1:00 PM,  <> wrote:
> Hallo allemaal,
> Here are the newest ASMs:
> During disassembling the ROMs I ran into various things I didn't
> understand. I wrote a page about my findings:

Very interesting issues and questions.

> I hope some of you will pay attention to it and give some comment.


The first thing that caught my eye was this:

"- The 9060 contains all the code for a second drive with the
exception of the Backup/Duplicate command."

I know that I looked into this in the past, not as deeply as you have,
but it all did seem to be in there.  When you say "all the code", it
suggests to me that if you were to format a drive installed normally
as drive 0, then move the jumpers so that it was drive 1, everything
should still work as long as you remembered to reference it as drive
1.  One consequence of that is that you could replace one TM602S with
two ST225s (and the right cabling) and as long as "drive 1" ST225 was
formatted in advance, it should behave the same, at the command level,
as an 8250.

Makes me wonder if there's room for "Backup/Duplicate" in the ROMs
(because that would be substantially faster than moving 5M/7.5MB both
ways over the IEEE bus)

The second thing I noticed was several points raised about the several
aspects of the formatting process.  I know that there are two distinct
versions of the ROMs with substantially different formatting times -
substantial enough to generate a note to CBM dealers about the
different (I have this note).  It might be interesting to compare
these parts of the code between the two versions for differences.  The
newer version takes 3-5 times longer than the original version, so I'm
sure users were concerned about how long it was taking (up to two
hours for a D9090, IIRC).


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Received on 2011-02-11 19:00:16

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