Computing Foundations

From Logic To Memory

status

seed

id

lesson.from-logic-to-memory

Orientation

The first lesson established that computers store patterns and meaning comes from interpretation. This lesson asks how the machine keeps those patterns around long enough to compute with them.

The path is deliberately small:

• A bit gives us two states.
• Boolean logic gives us rules over two-state values.
• Gates implement those rules physically.
• Circuits compose gates into useful behavior.
• Feedback makes a circuit remember.
• Latches and flip-flops hold one bit.
• Registers and RAM scale that stored state into usable memory.

Study Move

As you study, keep asking:

What makes this value persist?

If a signal changes and disappears immediately, it is only behavior in motion. If a circuit can keep a value available after the original input is gone, it has state. That is the conceptual jump from combinational logic to memory.

Source-Grounded Claims

• Petzold supports the claim that logic gates can be built from physical switching devices.
• Petzold supports the claim that feedback circuits can remember a bit of information.
• Petzold supports the claim that multiple latches can store multiple bits together.
• Nisan and Schocken support the claim that gates implement Boolean functions.
• Nisan and Schocken support the claim that DFFs, registers, and RAM form the memory devices used by the computer platform.

Source Anchors

• petzold-code-hidden-language-computer-hardware-software-2e
  • Chapter 10. Logic and Switches, near page 77 through page 91: switches and circuits as logic.
  • Chapter 11. Gates (Not Bill), near page 92 through page 123: relays and basic logic gates.
  • Chapter 14. Feedback and Flip-Flops, near page 146 through page 159: feedback, flip-flops, latches, clocks, and one-bit memory.
• nisan-schocken-elements-of-computing-systems-2e
  • Chapter 1 Boolean Logic, near page 34 through page 39: Boolean functions and gates.
  • Chapter 3 Memory, near page 78 through page 88: DFFs, registers, and RAM.

Open Questions

• This seed does not yet include a practical lab. A good first lab would be a tiny truth-table exercise followed by a hand-built latch diagram.
• The lesson does not yet connect memory to the fetch-execute cycle. That should probably be the next computing-foundations lesson after this one.