In the first instalment of this series, we introduced the Delphi programming environment and described several examples that illustrate how to program in Delphi. In this instalment, we take a more detailed look at the design of a somewhat more serious program. Our project here is to construct a simple pocket calculator in software. In next month’s instalment, it will be expanded to include a keypad that can be connected to a serial port to allow the keystrokes to be read by the Delphi program.
This project consists of three components:
- The presentation layer, which shows the results on the monitor.
- The driver layer, which provides the interface with the hardware (the keypad). This layer will be described in the next instalment.
- The processing layer, which is the software that simulates the operation of a pocket calculator.