The Evolution of ASCII, RS‑232, and Early Computer Terminals

Hardware Evolution

Modern computers now exchange data over TCP/IP, making the physical layer invisible, but in the pre‑Internet era communication relied on video display terminals (VDTs) and the RS‑232 serial protocol. VDTs replaced teletypes in the mid‑1970s, and Unix devices still retain names like tty and lp that echo those early printers.

RS‑232 and Modems

RS‑232, born in the early 1960s for teletype‑modem communication, survived for decades despite being superseded by USB and Ethernet. It used 7‑bit ASCII with an optional parity bit, and its standard 8N1 format was only unified in the mid‑1980s. Hayes Smartmodems introduced the AT command set, a convention still used in modern cellular modems.

Core Terminology

Before semiconductor memory, computers used ferrite core memory, giving rise to terms like “core” and “core dump.” These terms persisted into the 1990s even after multi‑core processors became common.

36‑Bit Systems and Octal

Early machines such as the DEC PDP‑10 and Symbolics 3600 used 36‑bit words, which naturally aligned with octal representation (12 groups of 3 bits). This architecture influenced early C language syntax and left a legacy of octal literals that persists in some modern languages.

Decline of RS‑232

By the 1990s RS‑232 usage dwindled, disappearing from mainstream PCs by 2010, though it remains in niche applications like GPS sensors and some industrial equipment that still rely on serial handshaking lines.

Pre‑Internet Wide‑Area Networks

Before the dominance of TCP/IP, networks such as UUCP, BBS, and FidoNet used modems and telephone lines to exchange email and files. Protocols like XMODEM, YMODEM, and ZMODEM enabled 8‑bit data transfer over 7‑bit links, and many of these conventions survive in modern tooling.

Terminal History

Early terminals like the ADM‑3 and DEC VT‑100 established the 80‑column display that modern terminal emulators still emulate. Control‑code standards (ANSI) and terminfo databases originated from this era, and the shift to bitmap color displays in the early 1990s finally retired most VDT hardware.

Early Computer Games

Text‑based games such as the Trek series, Rogue, Hack, and NetHack emerged on VDTs and early microcomputers, laying the groundwork for the roguelike genre and demonstrating how limited graphics could still deliver rich interactive experiences.

ASCII Table

The ASCII standard, introduced in the 1960s, remains the basis for the first 127 Unicode code points. The 1967 version differs slightly from the original 1963 table, and many control characters (0‑31) still serve special purposes in modern protocols.

Chronology of Milestones

A timeline lists key events from the 1961 MIT PDP‑1 release, through the rise of Unix, the advent of BBS and USENET, the spread of TCP/IP, to the dominance of 64‑bit systems and mobile platforms in the 2000s.

The article is excerpted from a translated piece in "Programmer" and is provided for technical sharing only.