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Intel C8253 Intel 8253 programmable interval timer. Intel 8254 has the same pinout. The Intel 8253 and 8254 are programmable interval timers (PITs), which perform timing and counting functions using three 16-bit counters. [1] The 825x family was primarily designed for the Intel 8080/8085-processors, but were later used in x86 compatible systems.
The Intel 8253 PIT was the original timing device used on IBM PC compatibles. It used a 1.193182 MHz clock signal (one third of the color burst frequency used by NTSC, one twelfth of the system clock crystal oscillator, [1] therefore one quarter of the 4.77 MHz CPU clock) and contains three timers.
The clock rate of the PC's programmable interval timer which drives the speaker is fixed at 1,193,180 Hz, [3] and the product of the audio sample rate times the maximum DAC value must equal this. Typically, a 6-bit DAC [ 8 ] with a maximum value of 63 is used at a sample rate of 18,939.4 Hz, producing poor but recognizable audio.
In computing, Intel's Advanced Programmable Interrupt Controller (APIC) is a family of programmable interrupt controllers.As its name suggests, the APIC is more advanced than Intel's 8259 Programmable Interrupt Controller (PIC), particularly enabling the construction of multiprocessor systems.
The documentation of Red Hat MRG version 2 states that TSC is the preferred clock source due to its much lower overhead, but it uses HPET as a fallback. A benchmark in that environment for 10 million event counts found that TSC took about 0.6 seconds, HPET took slightly over 12 seconds, and ACPI Power Management Timer took around 24 seconds. [6]
At the Macworld Conference and Expo on January 10, 2006, Steve Jobs announced that the new iMac would be the first Macintosh to use an Intel processors. The introduction of the new iMac alongside the MacBook Pro was the start of the Mac transition to Intel processors, six months earlier than the timetable Apple established. [4]
The references to two timers is not true. In Intel ICH4 documentation, the timer exists in IO ports 40h..43h, and the same timer is aliased to IO ports 50h..53h for some reason. A very good guess would be that the original IBM PC had it like this too to simplify IO address decoding, but this is just a guess.
A tickless kernel is an operating system kernel in which timer interrupts do not occur at regular intervals, but are only delivered as required. [1]The Linux kernel on s390 from 2.6.6 [2] and on i386 from release 2.6.21 [3] can be configured to turn the timer tick off (tickless or dynamic tick) for idle CPUs using CONFIG_NO_HZ, and from 3.10 with CONFIG_NO_HZ_IDLE extended for non-idle ...