Buffered Workstation Adapter Address Arrangement
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
The Buffered Workstation Adapter (BWSA) uses a psuedo-random number generator (ring counter) to generate its buffer address. On receive operations, the BWSA uses its byte count twice: once to count the number of return bytes from the workstation, and a second time to pass the correct number back to the host system. This means that the byte count must be maintained for the entire receive operation. The workstation microcode posses the byte count to the BWSA in byte 3 of the Serial Interface Control Block (SICB). To store it, the BWSA resets all but 2 bits of the ring counter and stores it in location 1022. The BWSA uses the same reset procedure to recall the byte count, put it in a decrement register, and wrap the ring counter to 0, pointing to first data location.