IBM PC - Hardware - Adapters - 1502074 Asynchronous Communications Adapter (1502074) Item number: 1502074 Announcement date: 1981-08-12 Availability date: 1981-08-12 Announcement letter: 281-65 THE IBM PERSONAL COMPUTER From the announcement: The Asynchronous Communications Adapter provides the IBM Personal Computer user with a channel to data processing or input/output devices outside of the immediate system. These can be connected by telephone using a plug-in modem, or directly by cable when the device is nearby. The communication "target" may be a large host computer, a Series/1, another IBM Personal Computer, a paper tape reader, a communicating typewriter, a laboratory instrument, or other machines providing the popular RS-232-C asynchronous interface. The Asynchronous Communications Adapter is flexible enough to match most of the computers and related products available in the microcomputer marketplace. The user's program selects the appropriate speed (50-9600 bps), format (5, 6, 7 or 8-bit characters), parity and stop bits to reflect the attached device. Once communication has been established, the user's program performs reads and writes. Interrupts permit the program to perform data processing such as calculating, diskette reading or writing, or printing, and then pause to resume communications when a signal appears on the line. The Asynchronous Communications Adapter has been verified to communicate with an IBM Series/1 with feature #1610, 2091/2092 attachment card using a sample program provided on the IBM Personal Computer DOS Diskette, and an application program running on Realtime Programming System Version 5 (5719-PC5) and Event Driven Executive Version 3 (5719-XS3). The Asynchronous Communications Adapter provides an EIA RS-232-C interface. One 25 pin "D" shell, male type connector is provided to attach various peripheral devices. In addition, a current-loop interface is located in the same connector. A jumper block is provided to select manually either the voltage or the current loop interface. BASIC language application programs supporting communications will require a diskette-based, minimum 32KB system containing DOS and the BASIC language extensions which include communications support. Page created: 2021-08-12 Page last updated: 2023-10-02