W8SDZ@SIMTEL20.ARPA (Keith Petersen) (12/16/87)
--forwarded message--
Relayed-From: RCP/M Royal Oak (313-759-6569)
Date: 14-Dec-87
From: Lee Rimar
Re: Ideas on file splitting
Sometimes I get a text file so large it becomes clumsy to edit.
WordStar gets very slow on big files, and hogs disk spaces. VDE
limits file size to available memory, usually around 48-52K.
There are file splitting programs, but they have problems. Many
are written in Pascal, big and slow. Assembly language versions are
much better. But they all work by copying the big file into several
small files. Time consuming, and takes up more disk space.
I have a faster way to do it. Maybe a trick "old hands" in CP/M
have known for years, but I've never seen/heard it mentioned:
Use a disk editor to modify the directory entry for the file.
Changing a few bytes in each physical directory extent can "split" a
file into several smaller files. Typically these files will be 16K,
but it depends on physical/logical extent layout.
You should work only with back-ups or scratch disk. Also a good
idea to run a directory "Sort & Pack" program first. A "cleaned-up"
directory is easier to work with.
With SODU82 (Screen Oriented DU, v8.2), I can split any size file
into 16K blocks in less than a minute. But I'm doing it manually. I
look at the directory entries, decide what bytes to change, and key in
the values myself. I think a program to automate this could do the
same thing in 2-3 seconds. But I've never seen such a program, and
don't know assembly language well enough to write one.
Which leads me to the 64K question(s): Has anyone ELSE seen such
a program? Would anyone consider writing one? Let me know . . .