An implantable active medical device or device for recording Holter data comprising: - a microcontroller comprising a microprocessor, - means for acquiring medical data, - a first memory, configured to store software for driving the microprocessor, and - a second memory, configured to store the medical data gathered by the acquisition means, in which the first and the second memory are, respectively, a first and a second sector of a single common memory component, the said common memory component is a single random-access memory circuit, i.e. RAM circuit, and the microcontroller furthermore comprises an interface circuit, cooperating with the microprocessor and the single common memory component; characterized in that - the microprocessor operates on N bits in parallel, the said common memory component is a memory organized as words of 2N bits, - the said driving software is stored in words of 2N bits of the first sector with logic protection managed by the interface circuit, each of these words comprising N bits of operation code forming control instruction for the microprocessor, and which are associated with n bits of error detector and corrector code, with 1 ≤ n ≤ N, - the said medical data are formed of N-bit elementary data stored in words of 2N bits of the second sector without logic protection, each of these words comprising N high-order bits and N low-order bits each storing an elementary medical datum, and - the interfacing circuit is configured, in a selective manner as a function of the said commands delivered by the microprocessor, to: • read or write in parallel the N+n bits of a word of the first sector, or else • read or write the N low-order bits of a word of the second sector, or else • read or write the N high-order bits of a word of the second sector. - a microcontroller comprising a microprocessor, - means for acquiring medical data, - a first memory, configured to store software for driving the microprocessor, and - a second memory, configured to store the medical data gathered by the acquisition means, - the microprocessor operates on N bits in parallel, the said common memory component is a memory organized as words of 2N bits, - the said driving software is stored in words of 2N bits of the first sector with logic protection managed by the interface circuit, each of these words comprising N bits of operation code forming control instruction for the microprocessor, and which are associated with n bits of error detector and corrector code, with 1 ≤ n ≤ N, - the said medical data are formed of N-bit elementary data stored in words of 2N bits of the second sector without logic protection, each of these words comprising N high-order bits and N low-order bits each storing an elementary medical datum, and - the interfacing circuit is configured, in a selective manner as a function of the said commands delivered by the microprocessor, to: • read or write in parallel the N+n bits of a word of the first sector, or else • read or write the N low-order bits of a word of the second sector, or else • read or write the N high-order bits of a word of the second sector. • read or write in parallel the N+n bits of a word of the first sector, or else • read or write the N low-order bits of a word of the second sector, or else • read or write the N high-order bits of a word of the second sector.