Abdul's Notes

HUJI - Build a Modern Computer from First Principles - From Nand to Tetris

2 min read

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Offered by the Hebrew University of Jerusalem
Found here - CS curriculums
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2024-12-31

  • Truth tables, boolean operations
  • NOT(0 OR (1 AND 1))
  • Commutative, associative and distributive laws
  • De Morgan Law → NOT(x AND y) = NOT(x) OR NOT (y)
  • x NAND y = NOT(x AND y)
  • NOT x = x NAND x
  • x AND y = NOT( x NAND y)
  • Gate interface ( what it does ) x implementation ( how it does )

2025-01-03

  • Multi-bit buses
    • Bus = Bunch of bits
    • Handling the input as a single entity
 
CHIP Add16 {
	IN a[16], b[16];
	OUT out[16];
 
	PARTS:
	...
}

2025-01-04

MSB → Most significant bit → a[15]
LSB → Least significant bit → a[0]
Multiplexor (Mux) Gate

  • Basically an if gate, the sel input picks if the a or b input if being output
    Demultiplexor (DMux) Gate
  • Input in, sel output a and b
if (sel == 0) 
	{a,b}={in,0}
else 
	{a,b}={0,in}

And16

16-bit 4-way mux

2025-01-13

Half Adder

  • Sum ~ XOR
  • Carry ~ AND

Full Adder

  • Two half adders

16-bit Adder

16-bit incrementor

ALU




2025-01-21


we need an abstraction for dealing with electricity instabilities, like the time it takes for a bit to flip, so we break the continuous time into discrete time and evaluate only the last state, in a clock

Flip Flop (D Flip Flop - DFF)

Simply a delayed version of the bit, will represent the input in the previous state , in[t-1]

1-bit Register


2025-01-29

  • Main memory
    • RAM
  • Secondary memory
    • Disks
  • Volatile / non-volatile
    • Volatile → looses data when powered off (RAM)

1-bit Register

8-Register RAM


Counters

  • fetch first instruction
  • fetch next instruction
  • go to instruction

Graph View