Method for Guaranteeing OEMI DATA Streaming Tag Widths for a Serial Channel Extender
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
The IBM OEMI Interface architecture specifies that, when data streaming at 4/5 megabytes/second, data transfer IN tags (SERVICE IN and DATA IN) must be at least 207 nanoseconds long and data transfer OUT tags (SERVICE OUT, DATA OUT, and COMMAND OUT) must be at least 130 nanoseconds long. A serial channel extender sends a serial frame each time one of the tags changes state. Each serial frame consists of three 50-nanosecond characters. The serial channel extender guarantees the width of the tags on the parallel interface by inserting a 50-nanosecond idle character after each frame, effectively making each frame 200 nanoseconds long. Since frames are being received at least 200 nanoseconds apart and each frame represents a tag change on the parallel interface, the tags are at least 200 nanoseconds long.