[Coco] Megaread problems

[Dave Philipsen]

And here's some more reasons I consider copy's inability to handle a 
device as '/dd@' a bug:

Dump knows how to do it right.  If I 'dump /dd@' it will dump all the 
way to the end of the device and stop.
Merge knows how to do it right. If I 'merge /dd@ >dd.img' it will create 
a file exactly the same size as the /dd device. (which, by the way, 
achieves the same result as the flawed 'copy /dd@ dd.img')


Dave

On 3/27/2017 5:25 PM, Bill Pierce via Coco wrote:
> Dave, Ded allows "@" due to the fact it only reads 256 bytes at a time. Again, a definite byte count, therefore "@" is just used to tell ded to start at the raw beginning of the device instead of a file location, which is actually handled in 256 byte sectors after the file is located anyway.
> Ded ALWAYS reads just 256 bytes (1 sector) at a time regardless of whether it's a file or raw device.
> Giving ded a filename is just a way of saying "start at sector xxxx and follow this sector pattern...".
> Giving ded "@" just tells it "Start on sector 0 and read the sectors contiguously".
> Using "@" on a file (ded /dd/cmds/dir@) gets the same results as it does without the "@". It will stop on the end of the file.
>
> Instead of adding "@" to copy, a better solution is "diskcopy" or "dsave", or even "backup" (when source and destination are of the same type & size), all of which will copy an entire disk.
> Then again, the ability to use "copy /dd /d1" would be handy....
> "One utility to bind them, one utility to rule them all!"
> :-)
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> Bill Pierce
> "Charlie stole the handle, and the train it won't stop going, no way to slow down!" - Ian Anderson - Jethro Tull
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