Hammer said this:
>> umpfh, dear Howard Schwartz, this is again coming back to byte you -
>> could you "expand" that cryptic remark ?
>> .. 'cuse I just wouldn't believe it's enough to use just another command
>> processor to overcome the DOS mem barrier.
About Howard's remark:
> Additionally, the born again shell is a 32-bit program that
> uses all available RAM. So its memory requirements are offset by the fact
> that it does not have to deal with the 16-bit DOS, 640K limit on
> conventional memory.
The born again shell (BASH) itself is complied with DJ Delorie's DJGPP
Compiler (for C and C++ source). It must be run with a dos extender that
provides DPMI (dos protected mode interface) services, which is usually
the program cwsdpmi.exe (freeware). That latter is started
automatically when the shell is run.
As a result, the shell program itself can use all available memory just
like windows can; it is not limited to the 640K memory model, and in
principle it can be run in a multitasking environment, since the memory it
uses is ``protected'' from conflicts with other programs in physical
memory. These statements apply as well to all the internal commands
that are part of this shell (cp, rm, mv etc.), and to its shell
scripts.
Of course, standalone programs that are launched from the BASH shell do
not themselves escape the 640K barrier, just because they were started
from this shell. Their code has already been written to use the usual
dos memory scheme. That is precisely why there are a host of dos
programs (e.g., less, gawk, sed, grep) that have been written for, or
recomplied with DJ Delorie's compiler: Once this is done these
programs can use all the memory windows does, as well. I use as
many DJGPP compiled dos programs as I can, since I find them faster
and capable of handling much larger files.
However, I do not use BASH or the ms_sh shell precisely because I
still run lots of DOS programs compiled to run under the old 640K
limit, memory scheme. The shells just take up too much memory for these,
conventional memory hungry older programs.
Hope this answers your question.
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