Commodore 64 Reset Logic


Posted on Feb 4, 2014

U20 is a 556 timer configured as a one shot multivibrator. The output pulse width is determined by the size of R34 and C24. Pulse width = 1. 1 x R34 x C24 =. 5 seconds. The output on pin 9 is `high` active. The output of U8 is `low` active. Reset initializes all the processor logic and causes the processor to load the program counter register withthe address


Commodore 64 Reset Logic
Click here to download the full size of the above Circuit.

of the first instruction of the operating system program called the KERNAL. The starting address is stored in locations $FFFC and $FFFD. The first instruction is decode and executed giving KERNAL control of the computer operations. The reset pulse occurs when turning the power on to the computer.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Oscillator-clock-generator
    Telephone-Operated Ac Power Switch
    Alarm circuit
    AMU2481 Audio Mixer
    Voltage follower
    With self-locking function of the forward start circuit
    HI-FI integrated amplifier TDA7294-01



    Top