Previously reported problems and how to deal with them

Problem or error

p. 43, exercise 2.5
Problems with installing the DJGPP compiler:
1) readme.html section 3, "Installation", advises you to copy three folders to c:\slp. This is not sufficient to install the DJGPP compiler. 

As stated in the later section, "DJGPP: a C compiler for MS-DOS", it is necessary to copy the DJGPP folder to C:\DJGPP (not c:\slp, which is harmless but useless), fix autoexec.bat, and restart your machine.

An updated version of readme.html is available here.

2) If you are running some versions of Windows XP, the compiler will still not work. Changing autoexec.bat
doesn't work in some versions of XP.
Add ;C\DJGPP\bin to the path variable and a new variable DJGPP with the value DJGPP.ENV. This is done via 'My Computer', but still results in a new error ...

3) Having installed DGJPP under Windows XP as above, attempting to run gcc yields the error message:
'An Extended Memory Manager is already installed. XMS driver not installed.'
DJGPP release 2.03 was buggy under 2000/XP, and some bugs remain even with the refresh release (

Many thanks are due to my colleagues Burton Rosner and Andrew Slater for getting to the bottom of this problem and spoon-feeding me with the solution.
To get DJGPP to behave under updated Windows XP:

Download the "refresh" version 2.03 of DJGPP.
Click on My Computer.
Find gcc.exe in the DJGPP\bin directory.
Right-click on it. This opens a new window.
Click on "Properties" to open it.
Click on "Memory" to open it.
Set XMS Memory to 8192.
Close all preceding windows.
Activate Command Prompt.
Change directory to c:\slp
Enter gcc -c coswave.c. A new file coswave.o results.
Enter gcc -o Bleep.exe coswave.o.
Bleep.exe results.
p. 112, line 64
The ASCII encoding of the diphthong /aI/ in is wrong:

accept([t,a,'I',m]).  -> no

accept([t,'&','I',m]. -> yes

(Reported by David Deterding: thanks David!)
Line 64 of should read:

Either type the correction yourself, or download a revised version of from here.

If the problem you are experiencing is not on the list above, there are some more steps you can try:

  1. If your computer is maintained or supported by professional computing service personnel (as is usually the case in an educational or business setting), please ask them for help. They should be able to give a second opinion regarding the problem, and may be able to solve it or suggest a course of further action. If you have no-one to call on, though, you'll have to go on to the next step.
  2. Alternatively, if all else fails, send me an email message. My email address is jóhn @ islp.ó Don't cut and paste the address from this web page: you'll have to type this in by hand into the "To:" field of your email composer. Leave out the spaces and the accents on the o's: they are just put in to make it harder for spammers to use this email address.
  3. Your message should include as much information as possible about the fault: what you were doing at the time, what you expected to happen, any error messages you got (preferably cut-and-pasted them into the message), what type of computer and what operating system you are using.
  4. In reply to your message, I promise nothing. However, if the bug really is an error in my software, I will try and fix it and add a report of how to fix it to the list of previously reported problems given above. I will probably not reply individually to your email message, unless I need further information about the problem. You should check this web page again from time to time to see if the fault you reported has been added to the list.

This page last edited on 6/1/04.