LAVA’s white paper on RS-232 serial ports has been a popular download for years. In 26 pages, this PDF covers a great deal of what you need to know to understand and use serial ports. It discusses what a serial port is, and looks closely at RS-232 (signalling, electrical, and mechanical aspects). UARTs are defined and their operation — stop and start bits, parity bits, data bits, buffers and triggers, Windows port configuration screens, and more — are covered. A section on how the UART structures serial communication really makes clear how serial ports operate.
On the practical side, RS-232 signal descriptions, details on connectors and cables, cable lengths, serial port resource requirements, addresses and interrupts, serial port line settings, and flow control are all discussed.
There’s lots more too — and you can download this white paper easily right here.