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From: WE AT completely DOT invalid (Wolfgang Ehrhardt)
Newsgroups: comp.os.msdos.djgpp,comp.os.msdos.programmer
Subject: Re: Why does PROMPT accept 128 characters if the command line is only 126?
Date: Fri, 11 Apr 2014 11:25:23 GMT
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On Thu, 10 Apr 2014 20:39:43 -0400, "Rod Pemberton"
<dont_use_email AT xnothavet DOT cqm> wrote:

>
>If the command line is 126 characters, why does PROMPT accept 128?
>
>In MS-DOS v7.10 (in real mode and Windows SE console), PROMPT will
>accept upto 128 characters for a new prompt, when using a single
>character prompt.  E.g.,
>
>   PROMPT $Q
>   PROMPT <...enter 128 characters...>
>
>RBIL says 128 bytes are available in the PSP, two of which are in-use.
>DJGPP says MAX_INPUT is 126 in limits.h.
>
>I'm hoping someone knows why this is off by two ...

Not the off by two, but: PROMPT accepts more than 128 characters in
Win98, only the command line interpreter limits the input (and adds a
space and a CR). If you prepare a batch file named lprompt.bat (with
all input on one line)

@prompt 12345678901234567890123456789012345678901234567890123456789
0123456789012345678901234567890123456789012345678901234567890123456789
01234567890123456789012345678901234567890

and execute it, you will see omething like this:

C:\>edit lprompt.bat

C:\>lprompt.bat

12345678901234567890123456789012345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567890123456789012345678901234567890
1234567890dir /b lprompt.bat
LPROMPT.BAT

12345678901234567890123456789012345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567890123456789012345678901234567890
1234567890