A relatively large block of random access memory ("RAM") may be provided on a programmable logic array integrated circuit device for use as read-only memory ("ROM") or RAM during operation of the device to perform logic. The RAM block is connected in the circuitry of the device so that it can be programmed...http://www.google.com/patents/US5633830?utm_source=gb-gplus-sharePatent US5633830 - Random access memory block circuitry for programmable logic array integrated circuit devices
