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Kekoa Proudfoot <kekoa@pixel.Stanford.EDU> wrote:
> It might be possible to eliminate the checksums to coerce my version to do
> quad-speed downloads, but I'd need to review the checksum settings used by
> the ROM to be sure, since my notes indicate that some of the alternate ROM
> checksum modes are broken.
Oops, I meant complements, not checksums, throughout the above paragraph.
After reviewing my notes, it seems that the ROM properly obeys the
complement flag when receiving but not when sending. When the ROM is
sending a "long" message, it sends a complemented opcode. "Short" messages
are tranmitted correctly. Fortunately, it is easy to detect the one
different case. Given this, I was able to double the speed of my firmware
stub, and downloads now proceed at a 4x rate. I also disabled the parity
bit as suggested by Markus, for a small additional improvement.
If the tower is not yet warmed up, the standard Lego firmware takes around
47 seconds to download, similar to what Markus reported. The times are
very close for large firmware files despite the shorter startup stub I
think because I have more ROM reply overhead; however, smaller firmware
files see up to around 6 seconds of improvement because of the shorter
startup stub.
I will package up my version shortly and post a URL.
Lighting conditions still seem to have a relatively large effect on whether
or not fast downloading is successful. For me specifically, my office has
fluorescent lighting, I can open and close the blinds to get some natural
light, and I have a box cover that I can use to cover the RCX and tower.
Some combinations of the above work well, some combinations do not work at
all, and some combinations seem to be intermittently reliable or flaky.
Once I release my version, I'd be curious to see how other people fare in
this regard. My experience has been that my office has difficult lighting
in it compared to other places, so maybe other people will have more
success where they are.
-Kekoa
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Message has 1 Reply:
 | | Re: fast firmware downloader
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| (...) The URL is: (URL) in the nick of time? The original firmdl.c was dated 10/3/98. It is currently 10/3/99 (PDT at least). This was not planned! Like firmdl.c, firmdl3.c is a single file joined from smaller ones for simplicity. I will link a .tgz (...) (25 years ago, 4-Oct-99, to lugnet.robotics.rcx.legos, lugnet.robotics.rcx)
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