bryce@hoser.berkeley.edu (Bryce Nesbitt) (12/07/87)
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Have any 1541C ROM revisions been made beyond part #251968-01?
If so, what exactly are the changes? (Don't fear being too technical)
^^^^^^^
Also, any running upgrades to the electronics that I should be
aware of (byond the track {zero,one} sensor)?
Answers to the above would be appreciated. Here is a list of what
I *do* already know:
This is a summary of the changes in that -01 ROM vs. the standard
901229-05 1541 ROM:
* Differing value loaded into DDRA at reset. (anti-hang)
* Automatic seek to track {zero,one} at reset (-compatibility problems-)
* Restarts all formats from the start, rather than trying to continue
an old failed format.
* Support for the track {zero,one} detector.
* Modifies the fundemental frequency of the job queue. (-compatability
problems-). This technique could be used to reduce time the job queue
wastes waiting for the next sector header to pop up. (It might have
been intended to change the step speed... but there are much better
ways to do that)
The save@ bug is *not* fixed, though it is very simple to add an
elegant patch to the upper half. (This could even be done to the
901229-05 ROM, without affecting the lower half)
I really need to know the answer to the above questions.
There is also as second, unimporant question to be tossed in:
What does the 1581 do about the job queue "mess"? Does it use the
same technique, or something new?
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