Questions tagged [8254]

for questions about the Intel 8254 Programmable Interval Timer

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6 votes
2 answers

Are there any known 8086 systems that would dynamically switch between XTAL and EFI clocks on 8284 clock generator?

In an typical 1980s 8086 system the 8284 clock chip is typically used to generate the clock for the CPU. The 8284 has two clock sources XTAL and EFI. XTAL provides a steady clock source from a ...
user4574's user avatar
  • 399
4 votes
5 answers

How to teach the Z80 to count milliseconds and microseconds like Arduino?

I make a homebrew (for hobby) game console on Z80A, and I need help. Now I'm stuck - I need to be able to count milliseconds and microseconds in the code. For example, how it is done in Arduino : ...
Alex's user avatar
  • 471
17 votes
1 answer

Why is the 8254's default rate 18.2 Hz?

The Intel 8253/8254 timer, in its default configuration, triggers IRQ0 18.2 times per second. Why this strange rate, and not something like 60 Hz (to match the most common video refresh rate) or 100 ...
Mark's user avatar
  • 8,550