A long-term study of ECG signal during everyday activity is required to obtain a broad spectrum of heart disease categories based on heart rate changing. Many techniques have been implemented, such as the use of a minicomputer in intensive care to observe patients [15], or microprocessor-based card in portable system [11, 18]. In this case, the disadvantage is the restriction of patient movement. A wire-free system connected to a hospital minicomputer allows patient mobility within restricted area in the hospital. Tape systems for recording ECG signals are bulky, heavy and prone to mechanical failure. In addition, these systems need large batteries. In order to reduce the size, weight and power consumption of the system, a single chip Reduced Instruction Set Computer (RISC) architecture microcontroller was chosen. To keep the patient free of movement at home [14, 19], a data transmission protocol using e-mail is implemented in the system [25]. Aspects that have been carefully considered are