DCAL is the DataCAD Application Language used to create most of the macros on this site. It is supplied with DataCAD so is available to any DataCAD user (although a little bit of previous programming experience would not go astray).
Classic DCAL has been around since the very early days of DataCAD, but more recently 2 new flavours of DCAL have been added: DCAL for Delphi, & DCAL for C++. I have not used DCAL for C++ so you won't find any information about it here (although I assume it is pretty similar to the Delphi flavour).
To use these new DCAL flavours you will also need the appropriate development environment which is not supplied with DataCAD (although I note that for personal or very limited commercial use you can download a free copy of Delphi).

Classic DCAL Source Code Editors

You can use any text editor to edit DCAL source code, but I recommend Notepad++. When used with an appropriate language definition, Notepad++ can highlight DCAL syntax as well as allowing bracket matching and code folding etc. I have developed a Notepad++ language definition for DCAL which you can download here.

Compiling Classic DCAL

The supplied compiler will not work on modern 64 bit versions of Windows. You could install a 32 bit virtual machine in order to compile your macros, but I have found that DOSBox is a useful tool with very little overhead and can be used to run the DCAL commpilers and linker (DOSBox does have it's limitations, the most obvious being that it can only handle up to 8 character file names, but I find I can work around that without to much of a problem).

DataCAD LLC host a DataCAD Developers Network forum on their web site, which can be a useful place to ask questions or find information relating to DCAL.

Source Code

The DCAL source code for many of my macros is available for download using the 'Macro Source' link in the menu at left. Please note that the source code is copyright. You are welcome to look at it to gain an understanding of how the macros work, and you may modify it for your own (or your company's) use, but you must not use it as the basis for a competing product that you make available to others. Generally speaking I would prefer that you asked me if you wish to make changes to one of the macros as I may be able to incorporate your change in the publicly released version of the macro.