Mi Atari is a 2600 SECAM (France) model. It has the same IC. It is common in computer systems to provide for a safe boot up mechanism for the processor. If the processor is fast and tries to boot immediately it is turned on, it could be that power rails, ic statuses, etc, have not stabilized, the processor can get confused and crash. So a delay between when initial power is applied and when the CPU is allowed to boot is put in place to avoid this.