Signals,systems&
thedeepcode.
Long-form engineering write-ups on how modern systems actually work. Articles, interactive browser-based labs, and quick recall quizzes.
What's inside
Every article ships with an interactive lab and a quiz.
Networking
TCP, DNS, BGP, QUIC, and the protocols that hold the internet together.
Operating Systems
Scheduling, virtual memory, containers, and the kernel underneath.
Security
TLS, cryptography, password hashing, and how systems get broken.
Databases
Write-ahead logging, crash recovery, storage engines, and consistency.
Hardware
CPU pipelines, DRAM internals, SSDs, and low-level silicon.
Signals & RF
GPS, radar, software-defined radio, and wireless from the physics up.
Latest
How 3-D Secure Actually Works
A technical deep dive into directory servers, issuer ACS systems, frictionless authentication, challenge flows, device fingerprinting, exemptions, soft declines, and liability shift.
How ATM Networks Actually Work
A technical deep dive into ATM switch routing, card verification, authorisation, dispensing control, cassette accounting, electronic journals, reversals, and settlement.
How Bank Reconciliation Actually Works
A technical deep dive into nostro accounts, sub-ledgers, statement matching, breaks, suspense, ageing, retry queues, and the operational reality of proving bank records agree.