![]() ![]() Note by Karoshier: my C64 schematic (1982 original taken from the programmer's reference guide) states the PAL master clock to be 17.734472MHz instead of 17.734475MHz, which does not actually make much of a difference with regard to the stated figure of CLOCK_PAL. U31 is a Clock Generator IC that outputs the 8.1818MHz DOT clock on pin 6, and the 14.31818 MHz color clock on pin 8. « Crystal Y1 develops the fundamental 16MHz clock signal. The description in this case is much more simple: In later models of the C64 (starting from version B, PCB ASSY#250425 Schematic #251469) the above gets integrated into a single chip labelled 8701, designed and manufactured on purpose by MOS technology. This Program creates any number of clocks with deferent time zones and many more. This causes tracking of the dot clock and the color clock because one input, pin 3 of U32, is the phase 0 clock which is derived from the dot clock, and the other input pin 1 of U32, is derived from the color clock. The output of the Phase/Frequency Detector is applied to the frequency control input pin 2 of U31. The VIC IC divides the DOT clock by eight and outputs this as the phase 0 clock on pin 17. Overview Telling time is an important part of everyday life. The second half of the Dual Voltage Controlled Oscillator U31 generates an 8.1818MHz clock signal called the DOT Clock. The Talking Clock software provides audible time announcements at user-defined intervals. U32 is a Phase/Frequency Detector which compares the output of the U29 to the phase 0 clock, and outputs a dc voltage on pin 8 that is proportional to the phase difference between the inputs. U29 is a D flip flop which outputs a 1 MHz signal on pin 9. U30 is a frequency divider that outputs a 2MHz signal on pin 6. R27 can be adjusted to obtain exact output frequency. The output on pin 10 is a 14.31818 MHz clock signal called the color clock. U31 is a Dual Voltage Controlled Oscillator. ![]() « Crystal Y1 develops a 14.31818MHz fundamental frequency clock signal. This is valid also for the PAL version when the appropriate differences in the figures are considered. The service manual (march 1992 original from Commodore, part number 314001-03) explains the clock circuitry the following way, using an NTSC machine as a reference. That's why the VIC-II internally provides a clock divider which feeds the CPU. 1MHz, but the CPU still needs to be phase synchronous to the VIC-II because they share control of the address/data bus of the machine. The CPU of the time could not go that fast, max. x86-64 (también conocido como 圆4, x8664, AMD64 e Intel 64) es la versión de 64 bits del conjunto de instrucciones x86.Soporta una cantidad mucho mayor de memoria virtual y memoria física de lo que le es posible a sus predecesores, permitiendo a los programas almacenar grandes cantidades de datos en la memoria. This is the so called “dot clock” which has to be very precise in order to keep the right timing needed to generate a video signal compatible with all TVs. The VIC-II runs at a frequency which is exactly 8 times that of the CPU. context.moveTo(clockX, clockY) // Start at the center context.lineTo(targetX, targetY) // Draw a line outwards. ![]() The CPU frequency is then calculated from that by simply dividing the frequency by 18 (PAL) or 14 (NTSC). All clock frequencies in the C64 are derived from a single clock quartz which has the frequency of 4 times the frequency of the color carrier used for PAL or NTSC. ![]()
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