Scalable n-port memory structures

Abstract

A scalable N-port memory device using as a building block a dual-port memory device core. The dual-port memory has two ports each of which can either serve as a read or a write port. The resulting N-port memory device, besides allowing for design reuse, offers speed, density and cost advantages over conventional N-port memory devices. For example, to realize a 1K word by 128 bit register file memory device having two write ports and either five or six read ports, three dual-port memory device cores are placed in parallel with one another. Each core has separate parallel (dual) read ports. Two write ports are shared in common among all of the cores. The cores are designed to operate at 2X speed, i.e., twice the desired speed of the N-port memory device. A 'cycle' at the N-port memory device is composed of two cycles of the underlying 2X speed devices, typically a read cycle followed by a write cycle. During the write cycle, corresponding locations of each of the device cores are written with identical information. The N-port memory device is well suited for design and layout as a memory compiler providing flexibility in specification of the number of ports, the number of words and the word width.