IBM RT Series Hardware Reference Manual page 369

TNL SN20-9844 (March 1987) to 75X0235
Control Graphic Operation Types
Branch and Link Queue
(X'3B')
The branch and link queue graphic operation allows branching to a specified queue location and
saves the queue pointer value for the next-in-line location for later use by the return queue
graphic operation.
Example: Branch and Link Queue, branch to queue address X'E015', and save the next queue
address X'EFFD' in the queue link pointer register for later use by the return queue operation.
Queue Queue Action
By
Address Data Queue Processing
X'FOOO' X'AOEO
Load RA with 8 high order bits of branch target queue pointer
value
X'EFFF'
X'B015 Load RA with 8 low order bits of branch target queue pointer
value
X'EFFE' X'D3BO Execute branch and link queue graphic operation
X'EFFD'
Link address for next operation after return queue.
Return Queue
(~'3C')
The return queue graphic operation returns from a branch and link queue operation to the
queue address, which was saved in the queue link pointer register. In the previous example, the
return queue graphic operation causes queue processing to return to the queue address
X'EFFD'.
Extended Monochrome Graphics Adapter 57