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Clock

A very important component of a CPU is the clock. A clock is a component that "ticks" regularly to synchronize processing. A clock typically contains a quartz or other materials with well-known and relatively constant oscillation period, and the clock circuitry maintain and measures this oscillation to maintain its sense of time.

CPU operations are done between clock ticks and read/writes are done in the ticks to ensure that all components move synchronously and not trample into each other while in intermediate states. In our (2,3) Turing Machine, between clock ticks electricity passes through the logic gates to calculate the output from the input (I1, I2, R(t)); and in the clock ticks, the tape writer will write O1,O2 to the tape, the motor will move depending on the value of M, and the internal register is written from the value of R(t+1), then the tape reader will read the current tape and put charge into I1,I2 and the internal register is reread back to R(t).

Source: How Do Computers Work?

The quoted excerpt gives an excellent explanation on the mechanism of CPU operations.

But I have difficulty pinning down the sense of "in the clock ticks". I think a clock tick marks a point in time while the time between the clock ticks marks a passage of time. How does the tape writer write something to the tape in the clock ticks?

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    I would have written "at" not "in". The text from which you're quoting makes a number of grammatical errors, BTW. – Tᴚoɯɐuo Jun 26 '16 at 13:38
  • Yep. I almost doubt it was written by a native speaker. e.g. "maintain and measures" :( – Kinzle B Jun 26 '16 at 13:46
  • clock ticks can be justified as a time span between two ticks. one triggers the record the other cause the record to stop. – Cardinal Jun 26 '16 at 13:56
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    "CPU operations are done between clock ticks and read/writes are done in the ticks to ensure that all components move synchronously and not trample into each other while in intermediate states." sounds like they meant to say "A CPU operation is done between clock ticks and a read/write operation is done at (or on) a clock tick to ensure (such and such)", which makes me wonder if they confused CPUs (in general) with (synchronous) digital circuits. – Damkerng T. Jun 26 '16 at 13:56
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    I would use "on a clock tick" same as you would use "on the hour" or "on the 15 min. mark". – user3169 Jun 26 '16 at 18:01
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A clock tick is an electric pulse or change of state and to understand what your passage is saying, one must understand that a tick (pulse) looks like this

here
events can be triggered on the 0->1 transition or the 1->0 transition. There are also minimal durations necessary for state 1 and state 0 to exist for them to be recognized. This is usually measured in milliseconds.

Data read/writes are performed while state 1 exists since it is used as the control signal for data to move along the I/O bus.

  • You don't explain why in is used, and whether it's idiomatic (an issue that seems pertinent). – Alan Carmack Jun 27 '16 at 13:06
  • I think Peter pretty much addressed that why - "minimal duration necessary for state 1 and state 0 to exist for them to be recognized". @AlanCarmack – Kinzle B Jun 27 '16 at 13:12

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