 The magazine of the Melbourne PC User Group How Much Do You Really Know? Tom Coleman |
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Well now! Going on the feedback received from the last test-yourself article, it really stirred things up.
One of the best comments received was - I don't have any trouble with DOS. I just did not understand those commands."
Truly those commands were not supposed to be tricky or difficult. We don t see why we should refrain from tricky or difficult things. After all it is nice to get to feeling pretty smug about lording ones superiority over the peasants.
For example.
What does
COPY . A:
do that Copy *.* a:
does not?
You may try that one if you wish. It is pretty harmless.
However there is the usual caveat about Melb PC having no responsibility for any outcome of your trying any of these commands. This includes maniacal murder of your loved ones as well as loss and damage to your data, hard disc, motor vehicle birthday or anything else.
You are on your own, surrounded by members. Some of whom I am sure can help you even if it is only to give explicit directions on how to slash your wrists.
What does FORMAT A: /H do?
Watch It. Have the right disk in drive A: before you press ENTER.
Just what does HIMEM.SYS do?
Does it really make your 384 kB of extended memory look like almost 448 kB?
Suppose you never get to know. Will you be any worse off for not knowing?
You may never know.
If you install a 1.2 MB floppy drive as drive B: what is involved in having the same drive accessed as a 360 kB drive E:, or the other way around if you like. That way you could address it as a 1.2 or a 360 just by changing drives. Very handy.
How is it done? I will give you a clue. Its all done through DOS. Software only. No hardware modification at all.
There is a great deal going about punching holes in 3.5 inch discs to make 720 kB discs into 1.44 MB discs, the merits of which will not be gone into. But what is the story with 5.25 inch discs?
What do you have to do to turn a 360 kB 5.25 inch floppy into a 1.2 MB floppy? Or will you be safer using a higher density disc to store your 360 kB data?
A knotty problem that you had better get right or you will be in diabolical trouble.
What is the effect of having a blank line at the end of a batch file?
How do you get a batch file to output a blank line?
How do you enter an Escape Character into a batch file using your favourite editor and then again using EDLIN, which we should all dearly love.
What would a line that gives three beeps look like in a batch file?
Some printers insist on printing a # instead of a
£ (the English pound sign). Why and what can be done about it? Now, before you try it at the keyboard, what does the following command produce:-
PROMPT $D$_$T$H$H$H$$_$P$G$_
Then how do you go back to what you had before?
On the other hand what does
PROMPT $_
produce and how do you get out of that?
What would happen in the following if you had no
*.ABC files in that directory?
DIR *.ABC > BANG.XYZ
COPY BANG.XYZ A:
Are you sure that you know why?
DOS has some obscure files that no one is quite sure about. Lovely files like RECOVER which apart from being very dangerous appear to serve no useful function.
Other files like ATTRIB and KEYB seem like they should be useful but its all a bit of a mystery. Heres is a command you can try. If it does not arouse your curiosity you should try again.
ATTRIB Filename.ext /s
Use it in the root directory of your hard disc and make the filename one from another directory.
Alternately you might try
ATTRIB G*.* /s
or any other leading letter you like. Go on try it. I promise it wont do anything too drastic.
While we are doing obscure things here is a good way to wreck a perfectly good .COM or .EXE file.
COPY COMMAND.COM+CON
Then type in anything you would like to add into command.com.
It will certainly not do anything useful and will almost certainly cause your system to crash at boot up time. But you must admit it is a fascinating way to go.
If you are not feeling so brutal you might try
COPY CONFIG.SYS+CON
[ENTER]
Then you type in
DEVICE=COLEMAN.SYS or something. [ENTER]
Then F6 or ^Z [ENTER]
Next time you boot up you will get a BAD or MISSING COLEMAN.SYS error.
Maybe you can find some other use for it. Like tacking a line on the end of an ASCII file without having to call up an editor or retype the lot with copy CON.
The nicest use I know for COPY CON is
COPY CON PRN
Suck it and see.
Postage Increase
Reprinted from the May 1991 issue of PC Update, the magazine of Melbourne PC User Group, Australia
