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Fig 4.2 Programming unit
4.3 Programming
4.3.1 Program design
The user memory can contain programs numbered from 0 to 9999. The programs in
the user memory together form a program block. The size of each program can be
adapted as required, provided that the total quantity of programs fit into the user
memory. The programmer has considerable freedom when designing a program
structure - frequently repeated operations, variants of operations and fault routines,
etc. are in separate programs.
Program changes can be effected according to two different principles:
• Within the memory by calling up a program. Calling-up in its simplest form involves:
1. Interrupting the running of the current program;
2. Running a different program;
3. Resuming the running of the current program.
A program which has been called up can in turn call up a third program, etc. up to 10
sub-levels
• The built-in floppy disk unit offers two possibilities:
- Replacement of the whole program block. All programs in the primary memory
are replaced by a new block of programs downloaded from the floppy disk.
After downloading a new program block, the newly loaded block of programs
starts running with program 0.
- Erasure of some programs and addition of a (short) program block. A desired
number of programs in the primary memory are replaced by a down-loaded
block of programs. After downloading a new program block, the current
program block continues running in the primary memory. Some of the old
programs are retained.
Description
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