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Article #5861

Environment size o = in PC-DOS 3.1

#5861
From: ROBIN
Date: Thu, 13 Mar 1986 13:35
71 lines
3016 bytes
Subject: Re: Anyone know how to enlarge the PC-DOS default environment size?
> 
Shekondar -

For some reason I was unable to reach you via mail, so I'm posting the
information to the net again.

                                       Max Robin
                   --------------------------------

This patch increase the environment size from 128 bytes to (H)0080 (128
decimal) paragraphs of 16 bytes each.

debug a:\command.com
-u cs:0f2b<cr>            ;DOS VERSION       LOCATION
                          ;2.X                CS:ECE
                          ;2.11(ATT&T PC6300) CS:DF2
                          ;3.0                CS:0F2B
                          ;contents should be MOV BX,000A
-a0f2b<cr>                ;address to asemble new code into
XXXX:0f2b mov bx,0080<cr> ;system prompts you with XXX:0f2b
-<cr>                     ;enter carriage return
-w<cr>                    ;write change
YYYY                      ;message telling how many bytes were written
-q<cr>                    ;quit

For DOS 3.1, an undocumented feature of the SHELL command is used
in the CONFIG.SYS file:

shell=drive/pathname_of_command_processor drive/path_to_command_process
      /p/e:number_of_16_byte_paragraphs

      where:  10<paragraphs<63

Example: c: is location of drive containing DOS 3.1 and config.sys
         expanding environment to 30 paragraphs of 16 bytes each,
         or 480 bytes

shell=c:\command.com c:\/p/e:30

               ---------------------------------

Alternative method to increase the environment size using DOS 3.1
 
Example below increases the environment size from 128 bytes to (H)0080 (128
decimal) paragraphs of 16 bytes each.

debug a:\command.com
-u cs:0d11<cr>
af3:0d11 0a00 or al,[bx+si]<cr>
-e 0d11<cr>
4af3:0d11 0a.80<cr>       ;system prompts you with '4af3:0d11 0a.'
                          ;you must type 80
                          ;3e gives 992 bytes, same as 62 paragraphs
                          ;of 16 bytes achieved by using SHELL patch
-<cr>                     ;enter carriage return
-w<cr>                    ;write change
YYYY                      ;message telling how many bytes were written
-q<cr>                    ;quit

               ---------------------------------


Max S. Robin
AT&T Bell Laboratories
Rm. 3E-318A
Whippany, NJ 07981
201-386-6865

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From: 2212msr@whuts.UUCP (ROBIN)
Newsgroups: net.micro.pc,net.micro
Subject: Environment size o = in PC-DOS 3.1
Message-ID: <584@whuts.UUCP>
Date: Thu, 13-Mar-86 08:35:59 EST
Article-I.D.: whuts.584
Posted: Thu Mar 13 08:35:59 1986
Date-Received: Sat, 15-Mar-86 02:10:54 EST
Distribution: net
Organization: AT&T Bell Laboratories
Lines: 71