Michael Maardt: PC since 1984 • on the net since 1990.

Get the most out of your PCDOS 6

The following description concerns Microsoft's edition of MS-DOS 6. The first thing to say is that simply installing DOS 6 will not make your PC run faster than it did using DOS 5.

I will confine myself to the parts of DOS 6 that are relevant to the rest of the booklet. Accessory programs like Undelete, Anti-virus, Interlink, Backup, and so on are not described, mainly because I do not use them.


It is possible to install so you can return to an earlier version. I consider this to be unrealistic and so I recommend that you type


which doesn't need uninstall diskettes. If you want to see all the setup options, type


Be prepared for the installation process to take some time. Certain resident disk-cache programs (not including SMARTDRV), delete-protection and anti-virus utilities that are not compatible with SETUP. I recommend that you suspend these during the installation process by writing REM at the beginning of each relevant line in your startup files, and then rebooting with SETUP disk # 1 in the drive.

You have the option of installing (1) only DOS, (2) only Windows or (3) both DOS and Windows versions of the three accessory programs. If you don't install everything now, you can always do so later. Just run Setup again.

I opted for the possibility of reverting to DOS 5, and a directory C:\OLD_DOS.1 was created, to which all files belonging to earlier DOS versions were copied. Note that files in C:\DOS that aren't overwritten by files from DOS 6 with the same name are left in C:\DOS. I would suggest that you make sure that before installation you only have DOS files and nothing else in this directory so that it is easier to find files after the process is finished ' in fact I copied the whole directory to C:\DOS5.

I was a little confused when I compared C:\OLD_DOS.1 with the new C:\DOS after installation. I thought that setup would actually copy everything in C:\DOS to C:\OLD_DOS.1 but it didn't. A file in C:\DOS that didn't belong to DOS 5 remained in C:\DOS. Setup works this way so that you can go back to DOS 5, but very few of you will want this.

When you've decided to keep DOS 6, you can delete C:\OLD_DOS.1; for example, by typing


The startup files are kept in the root directory. Boot with the new DOS 6 and you will see the first changes immediately. For two seconds, the screen shows

Starting MS-DOS..

Many users either didn't need, or were confused by, the technical messages produced by programs such as EMM386 and SMARTDRV so they are now removed by default. Good idea. If you want to see this information, as you could with DOS 5, insert /V somewhere in the line that calls EMM386 and SMARTDRV.

I was interested to see if anything had happened to my start files. Setup hadn't told me of anything during installation. I was rather surprised to see that now


shell=C:\DOS\command.com C:\DOS\ /p

had been added, without asking me, and had stolen some KB of my conventional memory. At least SETVER could have been placed in upper memory.


Big changes in the Help function. The whole DOS command manual is now online. For example you can type DIR/? to get quick, concise help about all the parameters and switches ' on screen. Type HELP DIR, and EDIT starts ' use the Tab key, or the initial letters, to move around the highlighted topics. It is very useful (and ecologically friendly) to be able to look things up immediately here instead of having to wade through a large book.

A long-awaited command is DELTREE, which can delete a directory together with its sub-directories.

C:\>deltree c:\extra


Using the parameter RAM EMM386 now takes all the extended memory under its wing and gives a program what it needs, whether this be EMS or XMS memory. This requires the use of a page frame, which occupies 64 KB in upper memory.

With DOS 5, only a certain amount of XMS could be converted to EMS memory ' whereupon it was "locked" in position as EMS. To release it, you had to alter your CONFIG.SYS and reboot your PC.

If you type the following in CONFIG.SYS

..emm386.exe ram min=0

you will see a screen message during boot to the effect that EMM386 can simulate any EMS or XMS memory a program needs. The above line is recommended if you sometimes need EMS memory and if you have 64 KB free in upper memory.

min=0 means that 256 KB is not reserved from the start, as it would be if min=0 was not specified.

You will be using 64 K in upper memory (which is taken from extended memory) but you don't need to concern yourself with whether your programs use EMS or extended memory.

See also Multiple Boots for how to get more control over how your memory is allocated.


MEMMAKER can do a lot to optimize your startup files.

Start by typing


to see what this program has to offer. The screen information from MEM is easier to read and understand in this version of the program. Type


and make a note of the information about free memory. That way it will be easier to follow the process when you run MEMMAKER.

Don't be nervous about running MEMMAKER. You can always go back to the previous configuration of your startup files, but only one step back. If you want to go back further, then you can add 1, 2 and so on to the startup files with the extension UMB. Remember that the files are in C:\DOS ' not too clever. At the DOS prompt enter this:


You can run either a configuration option called express or another called custom. The first thing MEMMAKER does is to copy your existing startup files in C:\DOS, adding the extension UMB to them. It then changes only your startup files, nothing else.

If you want to be able to revert to the previous file, i.e. one generation earlier, type


MEMMAKER inserts certain lines and adds all sorts of parameters and switches to others ' and there are a lot of changes!

I tried express first to see what would happen. The program booted my PC and ran various tests; this took a while. Screen messages keep you informed of how far MEMMAKER has progressed. Afterwards you can see the differences in your startup files.

The great thing with MEMMAKER is that you can run it again and again until you find the optimum configuration. Keep an eye on the screen in case of problems. I have not experienced any but if you do, you'll have to look in the manual. If everything gets in a mess, use


A selection is changed with the spacebar, and the arrow keys are used to move up and down between options.

Need expanded memory?

This affects the line with EMM386.EXE and its parameters. Both express and custom installations ask you if any of your programs need EMS memory. If you don't know, MEMMAKER advises you to answer No. If you answer Yes, RAM is inserted in this line, and if No, NOEMS is inserted.

These are the two possibilities available for making use of upper memory. As we saw earlier, the RAM parameter uses 64 KB for a page frame ' so it is important to have this space "spare" in upper memory; otherwise 64 KB will be taken from conventional memory.


The advanced choice is called both Custom and Advanced Options. The manual has only a very brief description of the advanced options, and the Help function isn't much better. The way I understand the information in Help is given below. Remember not to press Enter until after you have made all your choices. MEMMAKER adds various parameters to the line with EMM386.EXE.

Specify ..

If you haven't had problems while MEMMAKER is running, answer No. If you have experienced problems, the cause may be one of the programs loaded when the startup files are read. Answer Yes, and this option gives you the chance to answer Yes/No before every program is loaded and so find out which one is giving the problems.

When you've found the problem program, add REM in front of the line loading it, run MEMMAKER, then delete the REM so that the program loads. Microsoft recommends that you write the program's name (with or without an asterisk preceding it) in the c:\dos\memmaker.inf file, which has the same effect as my suggestion.

Scan the upper ..

By default, MEMMAKER (via EMM386) tries to manage all free space in upper memory. If you answer Yes to this (and you should answer Yes if you haven't had problems here), HIGHSCAN is inserted in the EMM386 line. You can answer No, which means that a safer area in upper memory is scanned. First try Yes, and if that doesn't work, use No. DOS 6.2 defaults to not using HIGHSCAN, i.e. it scans upper memory less aggressively.

Move Extended BIOS ..

Answer Yes and get an additional 1 KB conventional memory free. If you run into problems later, then run MEMMAKER again, answer No here and see if it fixes the problem. We're really into insignificant detail here.

Monochrome region..

See the drawing on upper memory. Many people these days have a "Super VGA" monitor, which displays at 800 x 600 resolution. If you know how to edit Windows' SYSTEM.INI, you should answer Yes. MEMMAKER inserts the parameter


in the line for EMM386.EXE.

Before running Windows, you edit Windows' SYSTEM.INI and write in the section [386Enh]:


If you run EGA or VGA (i.e. with a maximum resolution of 640 x 480), then experiment with Yes and see how it goes. If it works, you've "won" 32 KB in upper memory that you can use to run more programs. The acid test is trying to start Windows!

Keep current EMM386 ..

Here you can select what to do with the parameters I=.. and X=.., which include or exclude areas in upper memory. If you really understand the function of these parameters and what they include and exclude, then answer Yes, which means that your I=.. and X=.. will be kept; otherwise answer No.

If you answer No, you are letting MEMMAKER do the job, and maybe it can find something better.

Optimize..for Windows

This only affects the translation buffers, data in memory that Windows needs to be able to run DOS programs. At first I thought that this command could do more and actually optimize the whole Windows environment.

If I answer Yes, the lines WIN=EAOO-ECFF and WIN=EDOO-EFFF are inserted on my PC. MEMMAKER adds all these parameters in the EMM386.EXE line in order to reserve these addresses in upper memory for use as translation buffers, preventing anything else from using these UMBs.

My suggestion is to answer No and use MEM to check that you have 8 KB free (or 24 KB if you are on a network) in upper memory before Windows starts.

The manual and Help function go round and round the subject of DOS programs, running under Windows or not, and I'm still of the opinion that the manual is hopeless on this point. If you set up a config.sys with menus - as described Multiple Boots - and then run memmaker, memmaker cannot understand what to do. The only way around it is to divide them up into separate start files, run memmaker for each of them and then merge them together. Very complicated!

Important: Memmaker cannot change the order of devicehigh, which is the most important aspect of memory management. You have to do it manually.

In general, I would say that Memmaker is better than nothing, but I am not impressed.

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You are on michaelmaardt.com • © Michael Maardt 21. Jul. 2018