Mail-box design for non-blocking communication across ports of a

Abstract

A memory device (201) having left (203) and right (204) ports for communicating with left (205) and right (206) electronic devices, includes memory banks (401-0.about.401-7), semaphore logic (302), and port coupling circuitry (403, 404, 405-0.about.405-7, 406-0.about.406-7, 407-0.about.407-7). The semaphore logic generates bank access grant signals (313, 314) on a first received basis in response to bank access requests from the left and right electronic devices, and the port coupling circuitry couples selected memory banks to the left and right ports in response to the bank access grant signals. Also included in the memory device are mail-box registers (2500-0L.about.2500-3L, 2500-0R.about.2500-3R), interrupt generating circuitry (2514-0L.about.2514-3L, 2514-0R.about.2514-3R, 2900, 3000, 307, 308), and interrupt status and cause registers (3101L.about.3102L, 3101R.about.3102R, 3301L.about.3302L, 3301R.about.3302R). The left and right electronic devices use the mail-box registers to send messages to each other without waiting. The interrupt generating circuitry generates interrupts to notify the left and right electronic devices when their bank access requests have been granted, and when a message has been written into one of the mail-box registers for them. The interrupt status and cause registers provide information as to which memory banks the left and right electronic devices have been granted access to, and which mail-box registers contain messages for them.