Communication Protocol for Displaywriter-Personal Computer Data Transfers
Original Publication Date: 1985-Oct-01
Included in the Prior Art Database: 2005-Feb-19
A communication protocol is described which permits an IBM Displaywriter (DW) and a Personal Computer (PC) to communicate in a meaningful way through an Asynchronous communication link. The Cluster Attach Program (CAP) provides emulation of the PC's keyboard, display, and media, called logical devices, on the DW. DW and PC communicate using the asynchronous communication link. One byte of information at a time is transferred either from DW to PC or from PC to DW. Commo is a program module that handles the actual transferring of information between DW and PC. Logical devices use SEND and RECEIVE commands provided by Commo to exchange data with their counterparts without knowing that Commo is involved in the exchange. Data exchanged by the logical devices is usually a multi-byte string or block.