Modems & AT Commands

• Hayes Smartmodem 300/1200 Owner’s Manual (circa 1981–1983) — AT command set basics (AT, ATDT, ATH).
• General histories of the Hayes command set and “smartmodem” concept.

Atari Hardware

• Atari 835 Direct-Connect Modem Manual — SIO operation at 300 baud; dialing/answering from software.
• Atari 400/800 System Reference — BASIC I/O, device handlers, serial character streams.

BBS Origins

• CBBS (1978) histories and retrospectives.
• AMIS and other Atari BBS packages — early 1980s implementations.

Pre-Web Marketplaces & Consumer Services

• Boston Computer Exchange (1982) — BBS-based exchange.
• CompuServe Information Service — Electronic Mall (1984) and consumer features.
• Minitel (from 1982) — national dial-up services including commerce and messaging.
• The Source — consumer online service with news, conferencing, and shopping.