Why is there no clock in the Hack Computer Architechture?

[motty]

Hi,

I was wondering, why does the course not include the clock when discussing the Hack Computer architecture? From what I understood, the clock is a key component of a sequential computer, such as the Hack machine undoubtedly is....

I also feel that I lack a truly solid understanding of clocks / sequenitial logic, and I was hoping that actually building a clock and integrating it into the computer would help.

[WBahn]

For the same reason that you don't build a Nand gate or a DFF. Like these, a clock circuit is pretty much a primitive building block for a digital designer. Designing any of these requires knowledge that is beyond the scope of this class and requires more background before you're ready to do it.

Even in a course on digital logic the presence of a clock is generally assumed, as these circuits are fundamentally analog in nature. There are many kinds of clock circuits (more appropriately called oscillators) and these are generally covered in an analog circuits course. Some of them are very simple and pretty easy to understand in terms of basic principles, and others are quite complicated with a number of subtleties.

The main thing that you need to understand for all of the sequential logic in this project is that every DFF has the same clock signal going to it and that on the rising edge of the clock whatever was present on the 'in' input just prior to the clock edge appears on the 'out' output just after the clock edge.

[LBahn]