From: Baltissen, GJPAA (Ruud) (ruud.baltissen_at_abp.nl)
Date: 2004-08-31 16:26:02
Hallo allemaal,
I've got a question regarding compatibility:
- The CBM drives keep a copy of the BAM in memory. CBM-HD doesn't; it loads
the according BAM sector, changes the bit and saves the sector again. More
reliable IMHO. OK, more I/O but a very acceptable price.
If someone comes with a good reason to change this, I'll do it. But then one
question: at what point is the BAM in memory written back to disk?
I also wrote a PRG that copies a 8250 disk from one device to another.
Mainly writen in BASIC, the actual transfer is done in ML. Speed: about 650
bytes/sec, a 8250 floppy is copied in about 25 minutes. Interesting fact:
the built-in BACKUP command needs about the same time for a back-up. I
wonder why.
At this moment I copy the disk sector by sector. I started with reading a
complete track into memory but had to reduce the number of reads because of
an error. After finding the bug and a successfull run I did a run with a
track at the time again. And this run took more time !!! It puzzled me and
then I found out: the transfer of the the data from the CBM to my PC was
very fast but took enough time to make the 8250 stop the diskmotor. In order
to read the next track it has to start it again and this takes some extra
time.
Why is the above interesting? CBM-HD saves a 8250 disk as a D82 file and now
I have a tool to save the original WordCraft disks. Which is interesting for
Marko again :)
--
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/ __|__
/ / |_/ Groetjes, Ruud
\ \__|_\
\___| URL: Ruud.C64.org
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