luc@kulcs.uucp (Luc Van Braekel) (03/03/88)
I have noticed that it is possible to copy entire 360K diskettes using PC Tools (from Central Point Software), WITHOUT FORMATTING the target diskette first! I find this remarkable, since the copying process is faster than formatting a diskette, even when formatting with PC Tools. Are copies thus created less reliable than diskettes formatted in the right way ? Can someone give an explanation ? I have had no problems exchanging those diskettes with other PC users, so everything seems OK. +-----------------------------------+------------------------------------+ | Name : Luc Van Braekel | Katholieke Universiteit Leuven | | UUCP : luc@kulcs.UUCP | Department of Computer Science | | BITNET : luc@blekul60.bitnet | Celestijnenlaan 200 A | | fhgaa48@blekul11.bitnet | B-3030 Leuven (Heverlee) | | Phone : +(32) 16 20 0656 x3563 | Belgium | +-----------------------------------+------------------------------------+
davidsen@steinmetz.steinmetz.UUCP (William E. Davidsen Jr) (03/04/88)
Formatting is done at the track level. That is, the actual hardware
chip must be given the format command for each track, although the BIOS
often does this for you, and the format program calls the BIOS.
Good format and copy routines can do the following:
issue the format command for the track
issue a "write multiple" command on the same track
step to the next track
The write operation can come soon enough after the format command to
be done on the next revolution of the disk. Since the chip is doing the
write of multiple sectors, it can write the sectors in order (1:1
interleave) and therefore the effective write speed is two tracks/sec,
based on 6 rps, one rev for format, one for write, one for step. A
verify step can be added if desirable, reducing the effective speed to
1.5 track/sec.
There is no reason to think that a disk formatted in this way is less
reliable than any other.
CAVEAT: this is not complete. The are other details having to do with
64k boundaries, format parameters, DMA setup, etc. See the technical
manual for details.
--
bill davidsen (wedu@ge-crd.arpa)
{uunet | philabs | seismo}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -menather@ut-sally.UUCP (Ed Nather) (03/06/88)
In article <109@castor.kulcs.uucp>, luc@kulcs.uucp (Luc Van Braekel) writes: > I have noticed that it is possible to copy entire 360K diskettes using > PC Tools (from Central Point Software), WITHOUT FORMATTING the target > diskette first! MS-DOS "diskcopy" does the same thing. -- Ed Nather Astronomy Dept, U of Texas @ Austin {allegra,ihnp4}!{noao,ut-sally}!utastro!nather nather@astro.AS.UTEXAS.EDU