The memory

The memory holds the following information:

• a table of all names with their attributes (the name list),
• the stack, the heap and
• the definitions forming the program, in some internal form.

Unfortunately, present-day computers do not retain the contents of their memory upon being switched off, so that the memory must be explicitly written to a file in order to be able to read it back later.

During execution the executor tries to recycle all space in the heap taken up by objects that are no longer needed. It may however happen that a program needs more space than is available. Thus the memory can get exhausted; the only way out is to save the program in a file (by means of a write-command) and to start again.