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CS with Seongyeol

For aspiring CS students and non-majors
An interactive computer science series

- subscribers

Curriculum

4 parts, 30+ posts planned

Part 1 — Building a Computer from 0s and 1s

Why Computers Only Have Two Fingers

Binary, analog and digital

When Electricity Learned Logic

Boolean algebra, truth tables, Claude Shannon

Computers Are Made of 'Do You Like Mom or Dad?'

AND, OR, NOT gates, completeness

Actually, the Computer Didn't Like Both Mom and Dad

NAND gate, functional completeness

Where Do You Want to Go, Data?

multiplexer, decoder

A Calculator Made of Switches

half adder, carry

What the Front Digit Passes to the Back

full adder, ripple carry adder

Curing the Computer's Amnesia

Combinational vs sequential logic, SR latch, D latch

Teaching a Computer Rhythm

clock, D flip-flop, edge trigger

If It Only Calculates, It's a Calculator, Not a Computer

Turing machine, universal Turing machine, computability

Ask Von Neumann How to Assemble a Computer

Stored-program concept, machine code, memory, I/O devices

Talking to the CPU

registers, ALU, Zero Flag, instruction set

Fetch, Decode, Execute

Fetch-Decode-Execute cycle, control unit

Fast at Computing, Slow at Remembering

cache, cache hit, cache miss, locality, memory hierarchy

Part 2 — Thinking Like a Computer

할 일을 쪼개면 그게 알고리즘

자료구조, 알고리즘

02 Next post coming soon

Part 3 — No Computer Runs Just One Program Coming soon

Part 4 — How Computers Talk to Each Other Coming soon

Interactive Demos

01. Why Computers Only Have Two Fingers

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01. Why Computers Only Have Two Fingers

Binary (2 levels)Errors 0/24

Decimal (10 levels)Errors 6/24

The received signal is read as the nearest level. Green = correct read, Red = error.

Noise±20%

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02. When Electricity Learned Logic

A	B	A AND B
0	0	0
0	1	0
1	0	0
1	1	1

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04. Actually, the Computer Didn't Like Both Mom and Dad

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07. What the Front Digit Passes to the Back

100

1의 자리 반가산기

2의 자리 전가산기

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09. Teaching a Computer Rhythm

→

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09. Teaching a Computer Rhythm

→

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10. If It Only Calculates, It's a Calculator, Not a Computer

현재 상태	읽은 기호	다음 상태	쓸 기호	이동

초기 상태: q0 / 정지 상태: q_halt / 빈 칸: _ / 실행 전 테이프 클릭으로 값 수정 가능

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11. Ask Von Neumann How to Assemble a Computer

화면 (10×10)

VRAM

0: 흰색, 1: 검은색

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12. Talking to the CPU

Memory

→←

Registers

R00

R10

R20

R30

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12. Talking to the CPU

Registers

R05

R13

R20

R30

Result—

Z Flag0

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12. Talking to the CPU

MOVE Rd, Rs

Copies the value of Rs to Rd.

00004bit

Rd2bit

Rs2bit

MOVE R1, R200000110

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13. Fetch, Decode, Execute

Addr	Binary	Assembly
0	01100001	LDI R0, 1
1	01100110	LDI R1, 2
2	00010001	ADD R0, R1
3	10010101	STORE 5
4	11000010	JUMP 2
5	00000000	Data

PC0

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13. Fetch, Decode, Execute

0110

Imm

LDI R0, 3

Loads an immediate value into Rd.

RegisterImm → Rd

MemoryNot used

ALUNot used

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14. Fast at Computing, Slow at Remembering

Memory address

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14. Fast at Computing, Slow at Remembering

Memory address

Cache

····

RAMAll addresses

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14. Fast at Computing, Slow at Remembering

HitMiss

Hit rate -%

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14. Fast at Computing, Slow at Remembering

Memory address

··

~4 cycles

····

~10 cycles

········

~40 cycles

RAM

All addresses

~200 cycles

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15. 할 일을 쪼개면 그게 알고리즘

14327821

Find the smallest value in the unsorted part.
Swap it with the first value of the unsorted part.
The sorted part grows by one.
If one value remains, stop. Otherwise, go back to 1.

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15. 할 일을 쪼개면 그게 알고리즘

Target: 123

35812141719232628313537404246495154586163667073757882858790949699103106108111115118120123127130132135139141144148

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15. 할 일을 쪼개면 그게 알고리즘

Target: 123

35812141719232628313537404246495154586163667073757882858790949699103106108111115118120123127130132135139141144148

Read →