From: Spiro Trikaliotis (ml-cbmhackers_at_trikaliotis.net)
Date: 2007-09-06 20:58:44
Hello,
I came across some document that states that Commodore started to
exchange the ROMs at $E000-$FFFF of the 1540 and the 1541 with new
versions. It seems to be the change from the 901293-03 (in the 1541) or
the 325303-01 to the 901293-05 ROM. This is not very surprising, is it?
I always stumbled on the fact that there is a -04 missing in between the
1541 ROMs (901293-xx) ;)
Now, that document states that Commodore exchanged these ROMS with some
EPROMs. These are called "901229-05 AE" und "901229-06 AA".
Has anyone of you seen any of these?
It seems the 901229-05 AE has a format bug. Under some circumstances
(you abort formatting, for example, you open the door while formatting),
it would not format the whole disc; instead, it would "forget" to format
the lower tracks (1-xx). There is even a workaround present (M-W
command) to prevent this from occurring. (Write $FF to $0051.)
The document states that the -05 AE should be replaced by -06 AA EPROMs
because of this. Additionally, the -05 AE EPROMs should have the same
problem like the -03 ROMs (that is, Autostart is still present.)
To me, it seems as if that "901293-05 AE" EPROM might correspond to the
901293-04 ROM, and the "901293-06 AA" EPROM might correspond to the
901293-05 ROM. But, of course, there is no evidance.
Thus, I ask everyone: Has anyone seen a 1540 or 1541 (long or short
board!) with EPROMs, which look like original Commodore EPROMs (that is,
not the EPROMs from a floppy speeder. ;))? Has anyone seen any other ROM
(for example, a 9012293-04, -02 or -01)?
I would be very interested to get a dump of such an EPROM/ROM.
BTW, some trivia: The aforementioned document also states that the
cables had to be plugged in in a specific order: First, the interface
cable, and then, the net cable. The document describes some patches to
the 1540/1541 boards (1540007 A-E, 1540050 A-) to prevent this problem.
Some resistors and capacitors have to be replaced, as well as some
resistors have to be added. Thus, the patched board many people are
seeing might be a result of this problem.
Regards,
Spiro.
--
Spiro R. Trikaliotis http://opencbm.sf.net/
http://www.trikaliotis.net/ http://www.viceteam.org/
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