Category : Tutorials + Patches
Archive   : MEMHINTS.ZIP
Filename : DOS5HIGH.TXT

 
Output of file : DOS5HIGH.TXT contained in archive : MEMHINTS.ZIP

Loading COMMAND.COM high - the ultimate DOS 5.0 trick...

Any of you guys out there real memory freaks or just like to tinker with
DOS? Well, here's an original idea for you: load COMMAND.COM high. Not
just load it high, but load the primary copy high. Assuming you've got
a UMB server (you're using EMM386 or QEMM or something), here's one way
to do it...

You SHELL command in CONFIG.SYS probably looks something like this:

Shell = c:\command.com c:\dos /e:512 /p

What if you changed it to look something like this:

Shell = c:\command.com /c lh c:\command.com c:\dos /e:512 /p

What would that accomplish? Basically, what you're doing is loading a
temporary copy of COMMAND.COM and telling it to execute a statement and
immediately exit (the /C option). The command just happens to be
LOADHIGH COMMAND.COM. Although, the temporary copy gets "stuck" in low
memory (/C tells the first copy to exit, but the /P on the high copy
makes it permanent, so you can't exit back to the first to release it),
your primary copy of COMMAND.COM is loaded high. You computer finishes
the boot process as normal and nothing looks different. BUT, things are
different. The high copy of COMMAND.COM acts as a doorway to your high
memory. Try using a memory mapping utility such as MAPMEM (TurboPower
Software). You'll find that the map is not only your low memory, but
also your high memory. You'll also notice that any TSR you load from
the DOS prompt (even without LOADHIGH) will automatically become
resident in high memory. You'll notice a few extra k free down in low
conventional, and memory access (compare before and after speeds by
looking at CheckIt's Memory Map) in the high area is quite a bit faster.
What are the drawbacks? The only problems discovered to date are
related to TSRs, especially ones that try to update their status in
memory (they load fine, but don't try to change them). They tend to
lock up often, however, all major programs that I've tried run smoothly,
perhaps even a little faster.

Anybody out there that plays with this idea, please drop me a line - I'm
interested to see what you come up with. I have an idea of using NDOS
(which can load itself high to start with) to bounce the permanent copy
of COMMAND.COM off of. That should free up some more low memory. Let
me know of any developments you make.

Does Microsoft know the potential of doing this? Who's to say...

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

Greck S. Cannon
SysOp, Split Infinity
919 746-2517
USR Courier HST 14.4k V42bis

<*** End of Original File ***>



  3 Responses to “Category : Tutorials + Patches
Archive   : MEMHINTS.ZIP
Filename : DOS5HIGH.TXT

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

  2. This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

  3. But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/