![]() Because the 390 system clock will wrap in 2042, there is an issue for PFSes. 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. As part of the POSIX standards for 64-bit computing, which is known as LP64. 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. timet now char strftimebuf64 struct tm timeinfo time(&now) // Set. The description in this case is much more simple: The frequency deviation depends on the RTC Timer Clock Sources and affects the. 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 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. The second half of the Dual Voltage Controlled Oscillator U31 generates an 8.1818MHz clock signal called the DOT Clock. 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 free software is a nice addition to any desktop. This is valid also for the PAL version when the appropriate differences in the figures are considered. ClocX 64-bit is a handy traditional clock for your PC or laptop with a host of extra features. 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. 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. 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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